Axial Ax10 Scorpion Bodies
Axial Ax10 Scorpion Bodies
Axial ax10 scorpion rtr new suspension gears air filled tires body losi raminator urban rock crawl
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Aluminum Shock Body 12x55mm Scorpion (2) $21.99 Aluminum Shock Body 12x55mm Scorpion 2-pack… |
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Axial Racing RTR 1/10 SCX10 with Trail Honcho Body $584.99 The latest SCX10 is inspired by off-road vehicles that are basically part truck and part buggy, nicknamed “truggies”. The new Axial SCX10 is the kit to have when it comes to having a realistic looking truggy. Scale features such as the steel c-channel ladder frame, plastic molded cage, and plastic front bumper with aluminum skid plates are included in this kit. These are just a few of the features… |
Axial Led Controller W Lights
Axial Led Controller W Lights
Panther tank – Slurry Pump EGM – slurry pump impeller
Development and production Design This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (September 2009) The Panther was a direct response to the Soviet T-34 and KV-1 tanks.
First encountered on 23 June, 1941, the T-34 outclassed the existing Panzer III and IV. At the insistence of General Heinz Guderian, a special Panzerkommision was dispatched to the Eastern Front to assess the Soviet tanks. Among the features of the Soviet tank considered most significant were the sloping armor, which gave much improved shot deflection and also increased the effective armor thickness against penetration, the wide track, which improved mobility over soft ground, and the 76.2 mm gun, which had good armor penetration and fired an effective high-explosive round.
Daimler-Benz (DB) and Maschinenfabrik Augsburg-Nrnberg AG (MAN) were given the task of designing a new thirty to thirty-five-ton tank, designated VK30.02, by April 1942 (apparently in time to be shown to Hitler for his birthday). Panther on the Eastern Front, 1944. Panther Ausf. G in Houffalize, Belgium. The DB design was a direct homage to the T-34. It resembled the T-34 hull and turret form. DB’s design used a leaf spring suspension whereas the T-34 used coil springs. The DB turret was smaller than that of the MAN design and had a smaller turret ring which was the result of the narrower hull required by the leaf spring suspension which lay outside of hull. The main advantages of the leaf springs over a torsion bar suspension were a lower hull silhouette and a simpler shock damping design. Like the T34, the DB design had a rear drive sprocket. Unlike the T-34, the DB design had a three-man turret crew: commander, gunner, and loader. But as the planned L/70 75 mm gun was much longer and heavier than the T-34′s, mounting it in the Daimler-Benz turret was difficult. Plans to reduce the turret crew to two men to stem this problem were eventually dropped. The MAN design embodied more conventional German thinking with the transmission and drive sprocket in the front and a turret placed centrally on the hull. It had a gasoline engine and eight torsion-bar suspension axles per side. Because of the torsion bar suspension and the drive shaft running under the turret basket, the MAN Panther was higher and had a wider hull than the DB design. The slightly earlier, Henschel designed Tiger I heavy tank’s use of a “slack-track” Christie-style pattern of large road wheels with no return rollers for the upper run of track, and with the main road wheels being overlapping and interleaved in layout, were design concepts broadly repeated with the MAN design for the Panther. The two designs were reviewed over a period from January 1942 through March 1942. Reichminister Todt, and later, his replacement Albert Speer, both recommended the DB design to Hitler because of its several advantages over the initial MAN design. However, at the final submission, MAN improved their design, having learned from the DB proposal, and a review by a special commission appointed by Hitler in May 1942 ended up selecting the MAN design. Hitler approved this decision after reviewing it overnight. One of the principal reasons given for this decision was that the MAN design used an existing turret designed by Rheinmetall-Borsig while the DB design would have required a brand new turret to be designed and produced, substantially delaying the commencement of production. Production The MAN design also had better fording ability, easier gun servicing and higher mobility due to better suspension, wider tracks, and a bigger fuel tank. A mild steel prototype was produced by September 1942 and, after testing at Kummersdorf, was officially accepted.
It was put into immediate production. The start of production was delayed, however, mainly because there were too few specialized machine tools needed for the machining of the hull. Finished tanks were produced in December and suffered from reliability problems as a result of this haste. The demand for this tank was so high that the manufacturing was soon expanded beyond MAN to include Daimler-Benz, Maschinenfabrik Niedersachsen-Hannover (MNH) and Henschel & Sohn in Kassel. The initial production target was 250 tanks per month at MAN. This was increased to 600 per month in January 1943. Despite determined efforts, this figure was never reached due to disruption by Allied bombing, manufacturing bottlenecks, and other difficulties. Production in 1943 averaged 148 per month. In 1944, it averaged 315 a month (3,777 having been built that year), peaking with 380 in July and ending around the end of March 1945, with at least 6,000 built in total. Strength peaked on 1 September, 1944 at 2,304 tanks, but that same month a record number of 692 tanks were reported lost. Allied bombing was first directed at the common chokepoint for both Panther and Tiger production – the Maybach engine plant, which was bombed the night of April 2728, 1944. Production was shut down for five months, but a second plant had already been planned, the Auto-Union plant at Siegmar, and this came online in May 1944. Targeting of Panther factories began with a bombing raid on the DB plant on August 6, 1944, and again on the night of August 23-24, 1944. MAN was struck on September 10, October 3, and October 19, 1944, and then again on January 3 and February 2021, 1945. MNH was not attacked until March 14 and March 28, 1945. In addition to interfering with tank production goals, the bombing forced a steep drop in the production of spare parts. Spare parts as a percentage of tank production dropped from 2530 percent in 1943, to 8 percent in the fall of 1944. This only compounded the problems with reliability and numbers of operational Panthers as tanks in the field had to be cannibalized for parts. Production figures Panther tank production line The Panther was the third most produced German armored fighting vehicle. Production by type[citation needed] Model Number Date Notes Prototype 2 11/42 Designated V1 and V2 Ausf. D 842 1/43 to 9/43 Ausf. A 2,192 8/43 to 6/44 Sometimes called Ausf. A2 Ausf. G 2,953 3/44 to 4/45 Befehlspanzer Panther 329 5/43 to 2/45 Converted Beobachtungspanzer Panther 41 44 to 45 Converted Bergepanther 347 43 to 45 Panther production in 1944 by manufacturer Manufacturer % of total Maschinenfabrik Augsburg-Nrnberg (M.A.N.) 35% Daimler-Benz 31% Maschinenfabrik Niedersachsen-Hannover 31% Other 3% Cost One source has cited the cost of a Panther tank as 117,100 Reichmarks (RM). This compared with 82,500 RM for the StuG III, 96,163 RM for the Panzer III, 103,462 RM for the Panzer IV, and 250,800 RM for the Tiger I. These cost figures did not include the cost of the armament and radio. In terms of Reichmarks per ton, therefore, the Panther tank was one of the most cost-effective of the German AFV’s of World War II. However, these cost figures should be understood in the context of the time period in which the various AFVs were first designed, as the Germans increasingly strove for designs and production methods that would allow for higher production rates, and thus steadily reduced the cost of their AFVs. For example, another source has cited the total cost of the early production Tiger I in 19421943 to be as high as 800,000 RM. The process of streamlining the production of German AFVs first began after Albert Speer became Reichminister in early 1942 and steadily accelerated through 1944; production of the Panther tank thus coincided with this period of increased manufacturing efficiency. German AFV manufacturers at the start of World War II utilized only heavily labor-intensive and costly manufacturing methods unsuitable for the needs of mass production; even with streamlined production methods, Germany never approached the efficiency of Allied manufacturing during World War II. Design characteristics The Panther had a five man crew The weight of the production model was increased to 45 metric tons from the original plans for a 35 ton tank. Hitler had personally reviewed the final designs and insisted on an increase in the thickness of the frontal armor – the front glacis plate was increased from 60 mm (2.4 in) to 80 mm (3.1 in) and the turret front plate was increased from 80mm to 100 mm (3.9 in). The Panther was rushed into combat before all of its teething problems were corrected. Reliability was considerably improved over time, and the Panther did prove to be a very effective fighting vehicle; however, some design flaws, such as its weak final drive units, were never corrected due to various shortages in German war production. The crew was made up of five members: driver, radio operator (who also fired the bow machine gun), gunner, loader, and commander. Engine The first 250 Panthers were powered by a Maybach HL 210 P30 engine, V-12 gasoline engine which delivered 650 metric hp at 3000 rpm and had three simple air filters. Starting in May 1943, the Panthers were built using the 700 PS (690 hp, 515 kW)/3000 rpm, 23.1 litre Maybach HL 230 P30 V-12 gasoline engine. The light alloy block used in the HL 210 was replaced by a cast iron block to save aluminum. Two multistage “cyclone” air filters were used to automate some of the dust removal process. The HL 230 P30 engine was a very compact design which kept the space between the cylinder walls to a minimum. The crankshaft was composed of seven discs, each with an outer race of roller bearings, and a crankshaft pin between each disc. To reduce the length of the engine further, by one half a cylinder diameter, the two banks of 6 cylinders of the V-12 were not offset – the center points of the connecting rods of each cylinder pair in the “V” where they joined the crankshaft pin were thus at the same spot rather than offset; to accommodate this arrangement, one connecting rod in the pair of cylinders was forked and fit around the other “solid” connecting rod at the crankshaft pin. (A more typical “V” engine would have had offset cylinder banks and each pair of connecting rods would have fit simply side by side on the crankshaft pin). This compact arrangement with the connecting rods was the source of considerable teething problems early on. Blown head gaskets were another problem which was corrected with improved seals in September 1943. Improved bearings were introduced in November 1943 to replace the faulty ones that had failed frequently. An engine governor was also added in November 1943 that reduced the maximum engine speed to 2500 rpm. An eighth crankshaft bearing was added beginning in January 1944 to help reduce motor failures. The engine compartment space was designed to be watertight so that the Panther could be submersed and cross waterways. The result was that the engine compartment was poorly ventilated and prone to overheating. The fuel connectors in the early models were non-insulated, leading to leakage of fuel fumes into the engine compartment. This led to many engine fires in the early Panthers. Additional ventilation was added to draw off these gasses, which improved but did not completely solve the problem of engine fires. Other measures taken to reduce this problem included improving the coolant circulation inside the motor and adding a reinforced membrane spring to the fuel pump. The Panther had a solid firewall separating the engine compartment and the fighting compartment to keep engine fires from spreading to the crew. The engine became more reliable over time. A French assessment of their stock of captured Panthers in 1947 concluded that the engine had an average life of 1,000 km (620 mi) and maximum life of 1,500 km (930 mi). Suspension Interleaved wheels on a Panther The suspension consisted of front drive sprockets, rear idlers and eight double-interleaved rubber-rimmed steel road wheels on each side, suspended on a dual torsion bar suspension. The dual torsion bar system, designed by Professor Ernst Lehr, allowed for a wide travel stroke and rapid oscillations and high reliability, thus allowing for relatively high speed travel by this heavy tank over undulating terrain. However, the extra space required for the bars running across the length of the bottom of the hull, below the turret basket, increased the overall height of the tank and also prevented an escape hatch in the hull bottom. When damaged by mines, the torsion bars often required a welding torch for removal. The Panther’s suspension was complicated to manufacture and the interleaved system made replacing inner road wheels time consuming. The interleaved wheels also had a tendency to become clogged with mud and rocks and ice and could freeze solid overnight in the harsh winter weather of the Eastern Front. Shell damage could cause the road wheels to jam together and become extremely difficult to separate. Interleaved wheels had long been standard on all German half-tracks. The extra wheels did provide better flotation and stability and also provided more armor protection for the thin hull sides than smaller wheels or non-interleaved wheel systems, but the complexity meant that no other country ever adopted this design for their tanks. In September 1944, and again in March/April 1945, M.A.N. built a limited number of Panther tanks with steel roadwheels originally designed for the Tiger II and late series Tiger I tanks. Steel roadwheels were introduced from chassis number 121052 due to raw material constraints. From November 1944 through February 1945, a conversion process began to use sleeve bearings in the Panther tank, as there was a shortage of ball bearings. The sleeve bearings were primarily used in the running gear; plans were made also to convert the transmission to sleeve bearings but were not carried out as production of Panther tanks came to an end. Steering and Transmission Repair of the transmission of a Panther Steering was accomplished through a seven-speed AK 7-200 synchromesh gearbox, designed by Zahnradfabrik Friedrichshafen, and a MAN single radius steering system, operated by steering levers. Each gear had a fixed radius of turning, ranging from five meters for 1st gear up to 80 meters for 7th gear. The driver was expected to judge the sharpness of a turn ahead of time and shift into the appropriate gear to turn the tank. The driver could also engage the brakes on one side to force a sharper turn. This manual steering was a much simplified design compared to the more sophisticated dual radius hydraulically controlled steering system of the Tiger tanks. The AK 7-200 transmission was also capable of pivot turns, but this method of turning could accelerate failures of the final drive. Throughout its career, the weakest parts in the Panther were its final drive units. The problems of the Panther’s final drives were from a combination of factors. The original MAN proposal had called for the Panther to have an epicyclic/planetary (hollow spur) gear system in the final drive, similar to that used in the Tiger I. However, Germany at the time suffered from a shortage of gear-cutting machine tools and, unlike the Tiger tanks, the Panther was intended to be produced in large numbers. To achieve the goal of higher production rates, numerous simplifications were made to the Panther’s design and manufacturing. This process was aggressively pushed forward, sometimes against the wishes of designers and army officers, by the Chief Director of Armament and War Production, Karl-Otto Saur, who worked under (and later succeeded, in April 1945) Reichminister Albert Speer. And so the Panther’s final drive was changed to a double spur system. Although much simpler to produce, the double spur gears had inherently higher internal impact and stress loads, making them prone to failure under the high torque requirements of the heavy Panther tank. In contrast, both the Tiger II and the US M4 Sherman tank had double helical (herringbone) gears in their final drives, a system that reduced internal stress loads and was less complex than epicyclic/planetary gears. Germany’s wartime shortage of key alloying agents for making high strength steels also meant that to reach the desired high production rates a more readily available lower quality steel had to be substituted in the production of the double spur gears. Compounding these problems was the fact that the final drive’s housing and gear mountings were too weak, because of the type of steel used and/or because of the tight space allotted for the final drive; the gear mountings thus deformed easily under the high torque and stress loads, pushing the gears out of alignment and resulting in failure. The final drives of the Panther tank were so weak that their average fatigue life was only 150 km. In Normandy, about half of the abandoned Panther tanks were found by the French to have broken final drives. Plans were made to replace the final drive, either with a version of the original epicyclic/planetary gears planned by MAN, or with the final drive of the Tiger II. These plans were intertwined with the planning for the Panther II, and like the Panther II, never came to fruition. It was estimated that building the epicyclic/planetary gear final drive would have required 2.2 times more machining work, and this would have affected the manufacturing output. The mechanical unreliability of the Panther, a characteristic shared with the Tiger tanks, meant that long road marches would result in a significant number of losses due to breakdowns, and so the German Army had to ship the tanks by rail as close to the battlefield as possible. Armor Armor layout Initial production Panthers had a face-hardened glacis plate (the main front hull armor piece), but as armor-piercing capped rounds became the standard in all armies (thus defeating the benefits of face-hardening, which caused uncapped rounds to shatter), this requirement was deleted on March 30, 1943. By August 1943, Panthers were being built only with a homogeneous steel glacis plate. The Panther front hull had 80 mm of armor sloped back at 55 degrees from the vertical, welded but also interlocked for strength. The combination of a steep slope and thick armor meant that few Allied or Soviet weapons could penetrate this part of the tank. The armor for the side hull and superstructure (the side sponsons) was much thinner (4050 mm thick). The thinner side armor was necessary to keep the tank’s overall weight within reasonable bounds, but it made the Panther vulnerable to attacks from the side by most Allied and Soviet tank and anti-tank guns. German tactical doctrine for the use of the Panther thus emphasized the importance of flank protection. Five millimeter thick skirt armor, Schrzen, intended to provide protection for the lower side hull from Soviet anti-tank rifle fire was fitted on the hull side. Zimmerit coating against magnetic mines started to be applied at the factory on late Ausf D models beginning in September 1943 ; an order for field units to apply Zimmerit to older versions of the Panther was issued in November 1943. In September 1944, orders to stop all application of Zimmerit were issued, based on rumors that hits on the Zimmerit had caused vehicle fires. The rear hull top armor was only 16 mm thick, and had two radiator fans and four air intake louvres over the engine compartment that were vulnerable to strafing by aircraft. Panther crews were aware of the weak side armor and made unauthorized augmentations by hanging track links or spare roadwheels onto the turret and/or the hull sides. As the war progressed, Germany was forced to reduce or no longer use certain critical alloy materials in the production of armor plate, such as nickel, tungsten, molybdenum, and manganese; this did result in lower impact resistance levels compared to earlier armor. Manganese from mines in the Ukraine ceased when the German Army lost control of this territory in February 1944. Allied bombers struck the Knabe mine in Norway and stopped a key source of molybdenum; other supplies from Finland and Japan were also cut off. The loss of molybdenum, and its replacement with other substitutes to maintain hardness, as well as a general loss of quality control resulted in an increased brittleness in German armor plate, which developed a tendency to fracture when struck with a shell. Testing by U.S. Army officers in August 1944 in Isigny, France on three Panther tanks showed catastrophic cracking of the armor plate on two of the Panthers Armament The main gun was a 7.5 cm Rheinmetall-Borsig KwK 42 (L/70) with 79 rounds (82 on Ausf. G) with semi-automatic shell ejection. The main gun used three different types of ammunition, APCBC-HE (Pzgr. 39/42), HE (Sprgr. 42) and APCR (Pzgr. 40/42), the last of which was usually in short supply. While it was of only average caliber for its time, the Panther’s gun was one of the most powerful tank guns of WWII, due to the large propellant charge and the long barrel, which gave it a very high muzzle velocity and excellent armor-piercing qualities. The flat trajectory also made hitting targets much easier, since accuracy was less sensitive to range. The Panther’s 75 mm gun had more penetrating power than the main gun of the Tiger I heavy tank, the 8.8 cm KwK 36 L/56, although the larger 88 mm projectile might inflict more damage if it did penetrate. The tank typically had two MG 34 machine guns of a specific version designed for use in armored combat vehicles featuring an armored barrel sleeve. An MG 34 machine gun was located co-axially with the main gun on the gun mantlet; an identical MG 34 was located on the glacis plate and fired by the radio operator. Initial Ausf. D and early Ausf. A models used a “letterbox” flap opening, through which the machine gun was fired. In later Ausf A and all Ausf G models (starting in late November-early December 1943), a ball mount in the glacis plate with a K.Z.F.2 machine gun sight was installed for the hull machine gun. Turret Panther with regular mantlet. Panther with flattened lower (‘chin’) mantlet The front of the turret was a curved 100 mm thick cast armor mantlet. Its transverse-cylindrical shape meant that it was more likely to deflect shells, but the lower section created a shot trap. If a non-penetrating hit bounced downwards off its lower section, it could penetrate the thin forward hull roof armor, and plunge down into the front hull compartment. Penetrations of this nature could have catastrophic results since the compartment housed the driver and radio operator sitting along both sides of the massive gearbox and steering unit; more importantly four magazines containing main gun ammunition were located between the driver/radio operator seats and the turret, directly underneath the gun mantlet when the turret was facing forward. For the Ausf D and Ausf A models, a total of 27 rounds were stored in these magazines, which was reduced to 18 rounds for the Ausf G model. From September 1944, a slightly redesigned mantlet with a flattened and much thicker lower “chin” design started to be fitted to Panther Ausf G models, the chin being intended to prevent such deflections. Conversion to the “chin” design was gradual however, and Panthers continued to be produced to the end of the war with the rounded gun mantlet. In most cases the Panther’s gun mantlet could not be penetrated by either the M4′s 75 mm gun nor the T-34s 85 mm gun but could be penetrated by well-aimed shots at 100 m by the M4′s 76 mm gun, at 500 m by the Soviet A-19 122 mm gun on the IS-2 and at over 2500 yards (2286 m) by the British 17-pounder using APDS-ammunition. The side turret armor of 45 mm (1.8 in) was also vulnerable to penetration at long range by almost all Allied tank guns including the M4′s 75 mm gun which could punch through at 1500 m. These were the main reasons for continued work on a redesigned Panther turret, the Schmalturm, discussed later. The Ausf A model introduced a new cast armor commander’s cupola, replacing the more difficult to manufacture forged cupola. It featured a steel hoop to which a third MG 34 or either the coaxial or the bow machine gun could be mounted for use in the anti-aircraft role, though it was rare for this to be used in actual combat situations. The first Panthers, the Ausf D model, had a hydraulic motor that could traverse the turret at a maximum rate of 360 degrees in 60 seconds independent of engine speed. This slow traverse speed was improved in the Ausf A model with a hydraulic traverse that varied with engine speed, with a maximum rate of 360 degrees in 15 seconds if the engine was running at 3000 rpm. With the engine at 1000 rpm, the maximum traverse speed was 360 degrees in 46 seconds. A hand traverse wheel was like in any other tank, Axis or Allied, provided for the Panther gunner to fine tune the aim. This arrangement of the turret traverse mechanism was a slight weakness, as traversing the Panther’s turret rapidly onto a target required close coordination between the gunner and driver (to rev up the engine to maximum speed). By comparison, the M4 Sherman turret traversed at up to 360 degrees in 15 seconds and was independent of engine speed, which gave it an advantage over the Panther in close-quarters combat.. Ammunition Storage The locations for ammunition storage for the main 75 mm gun were a weak point of the Panther. No ammunition for the Panther was stored inside the turret, a positive given the weak side turret armor. However, a significant amount of ammunition was stored in the sponsons. In the Ausf D and A models, 18 rounds were stored next to the turret on each side, for a total of 36 rounds. In the Ausf G, which had deeper sponsons, 24 rounds were stored on each side of the turret, for a total of 48 rounds. In all models, 4 rounds were also stored in the left sponson between the driver and the turret. An additional 36 rounds were stored inside the hull of the Ausf D and A models – 27 in the forward hull compartment directly underneath the mantlet. In the Ausf G, the hull ammunition storage was reduced to 27 rounds total, with 18 rounds in the forward hull compartment. For all models, 3 rounds were kept under the turntable of the turret. The loader was stationed in the right side of the turret. With the turret facing forward, he had access only to the right sponson and hull ammunition, and so these served as the main ready-ammunition bins. The thin side armor could be penetrated at combat ranges by many Allied tank guns, and this meant that the Panther was vulnerable to catastrophic ammunition fires (“brewing up”) if hit from the sides. Combat use Panther tanks of the Grodeutschland Division advance in the area of Iai, Romania in 1944. Panther Ausf. Ds on rail cars in April/May 1943. Panthers were supplied to form Panzer Abteilung 51 (Tank Battalion 51) on 9 January, and then Pz.Abt. 52 on 6 February. The first production Panther tanks were plagued with mechanical problems. The engine was dangerously prone to overheating and suffered from connecting rod or bearing failures.
Gasoline leaks from the fuel pump or carburettor, as well as motor oil leaks from gaskets easily produced fires in the engine compartment; several Panthers were destroyed in such fires. Transmission and final drive breakdowns were the most common and difficult to repair. A large list of other problems were detected in these early Panthers and so from April through May 1943 all Panthers were shipped to Falkensee and Nuernburg for a major rebuilding program. This did not correct all of the problems, so a second program was started at Grafenwoehr and Erlangen in June 1943. Eastern Front The Panther tank was seen as a necessary component of the upcoming Operation Zitadelle, and the attack was delayed several times because of the mechanical problems of the Panthers, with the eventual start date of the battle only six days after the last of the Panthers had been delivered to the front. This resulted in major problems in the Panther units during the Battle of Kursk as tactical training on the unit level, coordination by radio, and driver training were all seriously deficient. It was not until the period of June 2329 that a total of 200 rebuilt Panthers were finally issued to Panther Regiment von Lauchert of the XLVIII Panzer Corps (4 Panzer Army). Two of the Panthers were immediately lost due to motor fires upon disembarking from the trains. By July 5, 1943, when the Battle of Kursk started, there were only 184 operational Panthers. Within two days, the number of operational Panthers had dropped to 40. On July 17, 1943 after Hitler had ordered a stop to the German offensive, Gen. Heinz Guderian sent in the following preliminary assessment of the Panthers: Due to enemy action and mechanical breakdowns, the combat strength sank rapidly during the first few days. By the evening of 10 July there were only 10 operational Panthers in the front line. 25 Panthers had been lost as total writeoffs (23 were hit and burnt and two had caught fire during the approach march). 100 Panthers were in need of repair (56 were damaged by hits and mines and 44 by mechanical breakdown). 60 percent of the mechanical breakdowns could be easily repaired. Approximately 40 Panthers had already been repaired and were on the way to the front. About 25 still had not been recovered by the repair service… On the evening of 11 July, 38 Panthers were operational, 31 were total writeoffs and 131 were in need of repair. A slow increase in the combat strength is observable. The large number of losses by hits (81 Panthers up to 10 July) attests to the heavy fighting. A later report (generated every ten days) of the inventory of Panthers on July 20, 1943 showed 41 Panthers as operational, 85 as repairable, 16 severely damaged and needing repair in Germany, 56 burnt out (due to enemy action), and 2 that had been destroyed by motor fires. However, before the Germans ended their offensive at Kursk, the Soviets began their counteroffensive, and succeeded in pushing the Germans back into a steady retreat. Thus, a report on August 11, 1943 showed that the numbers of total writeoffs in Panthers swelled to 156, with only 9 operational Panthers. The German Army was forced into a fighting retreat and increasingly lost Panthers in combat as well as from abandoning and destroying damaged vehicles. The Panther demonstrated its capacity to destroy any Soviet AFV from long distance during the Battle of Kursk, and had a very high overall kill ratio. However, it comprised less than seven percent of the estimated 2,4002,700 total AFVs deployed by the Germans in this battle, and its effectiveness was limited by its mechanical problems and the in-depth layered defense system of the Soviets at Kursk. Its greatest historical role in the battle may have been a highly negative one – its contribution to the decisions to delay the original start of Operation Zitadelle for a total of two months, time which the Soviets used to build up an enormous concentration of minefields, anti-tank guns, trenches, and artillery defenses. After the losses of the Battle of Kursk, the German Army went into a permanent state of retreat against the Red Army. The numbers of Panthers were slowly re-built on the Eastern Front, and the percentage of operational Panthers increased as its reliability was improved. In March 1944, Guderian reported of the Panther: “Almost all the bugs have been worked out”, although many Panther units continued to report significant mechanical problems, especially with the final drive. The greatly outnumbered Panthers came to be used as mobile reserves to fight off major attacks. The highest total number of Panthers listed as operational on the Eastern Front was achieved in September 1944, when some 522 Panthers were listed as operational out of a total of 728. Throughout the rest of the war, Germany continued to keep the great majority of Panther forces on the Eastern Front, where the situation progressively worsened for the Germans. The last recorded status of Panther forces, on March 15, 1945, listed 740 Panthers on the Eastern Front with 361 operational. By this time the Red Army had entered East Prussia and was advancing through Poland. Western Front – France At the time of the invasion of Normandy, there were initially only two Panther-equipped Panzer regiments in the Western Front, with a total of 156 Panthers between them. From June through August 1944, an additional seven Panther regiments were sent into France, reaching a maximum strength of 432 in a status report dated July 30, 1944. The majority of German panzer forces, six and a half divisions, were drawn into the British Second Army sector in the open country around Caen; the numerous battles became collectively known as the Battle of Caen. US forces in the meantime, facing one and a half German panzer divisions, mainly the Panzer Lehr Division, struggled in the heavy, low-lying bocage terrain west of Caen. Against the M4 Shermans of the Allied tank forces during this time, the Panther tank proved to be most effective when fighting in open country and shooting at long range – its combination of superior armor and firepower allowed it to engage at distances from which the Shermans could not respond.. However, the Panther struggled in the bocage country of Normandy and was vulnerable to side and close-in attacks in the built-up areas of cities and small towns. The commander of the PanzerLehr Division, Gen. Fritz Bayerlein made these comments about the weaknesses of the Panther tank in the fighting in Normandy: While the PzKpfw IV could still be used to advantage, the PzKpfw V [Panther] proved ill adapted to the terrain. The Sherman because of its maneuverability and height was good…[the Panther was] poorly suited for hedgerow terrain because of its width. Long gun barrel and width of tank reduce maneuverability in village and forest fighting. It is very front-heavy and therefore quickly wears out the front final drives, made of low-grade steel. High silhouette. Very sensitive power-train requiring well-trained drivers. Weak side armor; tank top vulnerable to fighter-bombers. Fuel lines of porous material that allow gasoline fumes to escape into the tank interior causing a grave fire hazard. Absence of vision slits makes defense against close attack impossible. Through September and October, a series of new Panzer-Brigades equipped with Panther tanks were sent into France to try to stop the Allied advance with counterattacks. This culminated in the Battle of Arracourt (September 1829, 1944), in which the mostly Panther-equipped German forces suffered heavy losses fighting against the 4th Armored Division of Patton’s 3rd Army, which were still primarily equipped with 75 mm M4 Sherman tanks and yet came away from the battle with only a few losses. The Panther units were newly formed, poorly trained, and tactically disorganized; most units ended up stumbling into ambush situations against seasoned U.S. tank crews. Western Front – Ardennes Offensive Burnt out Panther Ausf.G at the Battle of the Bulge, penetrated in the sponson. A status report on December 15, 1944 listed an all time high of 471 Panthers assigned to the Western Front, with 336 operational (71 percent). This was one day before the start of the Battle of the Bulge; 400 of the tanks assigned to the Western Front were in units sent into the offensive. The Panther once again demonstrated its prowess in open country, where it could shoot its victims at long range with near-impunity, and its vulnerability in the close-in fighting of the small towns of the Ardennes, where there were heavy losses. A status report on January 15, 1945 showed only 97 operational Panthers left in the units involved in the operation, out of 282 still in their possession. Losses were 198 Panthers listed as total write-offs. The Operation Greif commando mission included five Panthers assigned to Panzerbrigade 150 disguised to look like M10 Tank Destroyers by welding on additional plates, applying US-style camouflage paint and markings. This was carried out as part of a larger operation that involved soldiers disguised as Americans and other activities. The disguised Panthers were detected and destroyed. In February 1945, eight Panzer divisions with a total of 271 Panthers were transferred from the West to the Eastern Front. Only five Panther battalions remained in the west. One of the top German Panther commanders was SS-Oberscharfhrer Ernst Barkmann of the 2nd SS-Panzer Regiment “Das Reich”. By the end of the war, he had some 80 tank kills claimed. Fortification Pantherturm fortification in Italy, mid 1944. From 1943, Panther turrets were mounted in fixed fortifications, some were normal production models, but most were made specifically for the task, with additional roof armour to withstand artillery. Two types of turret emplacements were used; (Pantherturm III – Betonsockel concrete base) and (Pantherturm I – Stahluntersatz steel sub-base). They housed ammunition storage and fighting compartment along with crew quarters. A total of 182 of these were installed in the fortifications of the Atlantic Wall and West Wall, 48 in the Gothic Line and Hitler Line, 36 on the Eastern Front, and 2 for training and experimentation, for a total of 268 installations by March 1945. They proved to be costly to attack, and difficult to destroy. Panther battalion organization From September 1943, one panzer battalion with 96 Panthers comprised the panzer regiment of a Panzer-Division 43. Panzerbefehlswagen Panther Ausf. A (Sd.Kfz. 267) of the Panzergrenadier-Division Grodeutschland photographed in southern Ukraine in 1944. Battalion Command (composed of Communication and Reconnaissance platoons) Communication Platoon – 3 Befehlswagen Panther SdKfz.267/268 Reconnaissance Platoon – 5 Panther 1st Company – 22 Panther Company Command – 2 Panther 1st Platoon – 5 Panther 2nd Platoon – 5 Panther 3rd Platoon – 5 Panther 4th Platoon – 5 Panther 2nd Company – 22 Panther (composed as 1st Company) 3rd Company – 22 Panther (composed as 1st Company) 4th Company – 22 Panther (composed as 1st Company) Service Platoon – 2 Bergepanther SdKfz.179 From 3 August 1944, the new Panzer-Division 44 organisation called for a panzer division to consist of one panzer regiment with two panzer battalions one of 96 Panzer IVs and one of 96 Panthers. Actual strengths tended to differ, and became far lower after losses. The Allied response Soviet The importance of the tank on the Eastern Front led to an arms race between the Germans and Soviets to produce AFVs with ever greater armor and firepower. The Tiger I and Panther tanks were German responses to encountering the T-34 in 1941. Soviet firing tests against a captured Tiger in April 1943 showed that the T-34′s 76 mm gun could not penetrate the front of the Tiger I at all, and the side only at very close range. An existing Soviet 85 mm antiaircraft gun, the 52-K, was found to be very effective against the frontal armor of the Tiger I, and so a derivative of the 52-K 85 mm gun was developed for the T-34. The Soviets thus had already embarked on the 85 mm gun upgrade path before encountering the Panther tank at the Battle of Kursk. After much development work, the first T-34-85 tanks entered combat in March 1944. The production version of the T-34′s new 85 mm gun proved to be ineffective against the Panther’s frontal armor, meaning the Soviet tank had to flank the Panther to destroy it, while the Panther’s main gun could penetrate the T-34 at long range from any angle. Although the T-34-85 tank was not quite the equal of the Panther, it was much better than the 76.2 mm-armed versions and made up for its quality shortcomings by being produced in greater quantities than the Panther. New self-propelled anti-tank vehicles based on the T-34 hull, such as the SU-85 and SU-100, were also developed. A German Army study dated October 5, 1944 showed that the Panther could easily penetrate the turret of the T-34-85 from the front at ranges up to 2000 m, and the frontal hull armor at 300 m, whereas from the front, the T-34-85 could only penetrate the non-mantlet part of the Panther turret at 500 m. From the side, the two were nearly equivalent as both tanks could penetrate the other from long range. The Battle of Kursk convinced the Soviets of the need for even greater firepower. A Soviet analysis of the battle in August 1943 showed that a Corps artillery piece, the A-19 122 mm gun, had done well against the German AFVs in that battle, and so development work on the 122 mm equipped IS-2 began in the fall of 1943. Soviet tests of the IS-2 versus the Panther included a claim of one shot that could penetrate the Panther from the front armor through the back armor. However, German testing showed that the 122 mm gun could not penetrate the glacis plate of the Panther at all, but it could penetrate the front turret/mantlet of the Panther at ranges up to 1500 m. The Panther’s 75 mm gun could penetrate the front of the IS-2s turret at 800 m and the hull nose at 1000 m. From the side, the Panther was more vulnerable than the IS-2. Thus the two tanks, while nearly identical in weight, had quite different combat strengths and weaknesses. The Panther carried much more ammunition and had a faster firing cycle than the IS-2, which was a lower and more compact design; the IS-2s A-19 122 mm gun used a two piece ammunition which slowed its firing cycle. American and British The Western Allies’ response was inconsistent. The Panther was not employed against the western Allies until early 1944 at Anzio, where Panthers were employed in small numbers. Until shortly before D-Day, the Panther was thought to be another heavy tank that would not be built in large numbers. However, just before D-Day, Allied intelligence investigated Panther production, and using a statistical analysis of the road wheels on two captured tanks, estimated that Panther production for February 1944 was 270, thus indicating that it would be found in much larger numbers than had previously been anticipated. In the planning for the Battle of Normandy, the US Army expected to face a handful of German heavy tanks alongside large numbers of Panzer IVs, and thus had little time to prepare to face the Panther. Instead, 38% of the German tanks in Normandy were Panthers, whose frontal armor could not be penetrated by the 75 mm guns of the US M4 Sherman. The British were more astute in their recognition of the increasing armor strength of German tanks, and had by the time of the Normandy invasion started a program to mount the excellent 17-pounder anti-tank gun on some of their M4 Shermans (Sherman Firefly). British and Commonwealth tank units in Normandy were initially equipped at the rate of 1 Firefly to 3 Shermans or Cromwells. This increased until by the end of the war, half of the British Shermans were Fireflies. The 17-pounder had slightly more punch at long range than the Panther’s 75 mm gun. The US armor doctrine at the time was dominated by the head of Army Ground Forces, Gen. Lesley McNair, an artilleryman by trade, who believed that tanks should concentrate on infantry support and exploitation roles, and avoid enemy tanks, leaving them to be dealt with by the tank destroyer force, which were a mix of towed anti-tank guns and lightly armored AFVs with open top turrets with 3-inch (M-10 tank destroyer), 76 mm (M18 Hellcat) or later, 90 mm (M36 tank destroyer) guns. This doctrine led to a lack of urgency in the US Army to upgrade the armor and firepower of the M4 Sherman tank, which had previously done well against the most common German armor – Panzer IIIs and Panzer IVs – in Africa and Italy. As with the Soviets, the German adoption of thicker armor and the 7.5 cm KwK 40 in their standard AFVs prompted the U.S. Army to develop the more powerful 76 mm version of the M4 Sherman tank in April 1944. Development of a heavier tank, the M26 Pershing, was delayed mainly by McNair’s insistence on “battle need” and emphasis on producing only reliable, well-tested weapons, a reflection of America’s 3,000 mile supply line to Europe. U.S. awareness of the inadequacies of their tanks grew only slowly. All U.S. M4 Shermans that landed in Normandy in June 1944 had the 75 mm gun. The 75 mm M4 gun could not penetrate the Panther from the front at all, although it could penetrate various parts of the Panther from the side at ranges from 400 m to 2600 m. The 76 mm gun could also not penetrate the front hull armor of the Panther, but could penetrate the Panther turret mantlet at very close range. In August 1944, the HVAP (high velocity armor-piercing) 76 mm round was introduced to improve the performance of the 76 mm M4 Shermans. With a tungsten core, this round could still not penetrate the Panther glacis plate, but could punch through the Panther mantlet at 800 to 1000 yards, instead of the usual 100 yards for the normal 76 mm round. However, tungsten production shortages meant that this round was always in short supply, with only a few rounds available per tank, and some M4 Sherman units never received any. The 90 mm M36 tank destroyer was introduced in September 1944; the 90 mm round also proved to have difficulty penetrating the Panther’s glacis plate, and it was not until an HVAP version of the round was developed that it could effectively penetrate it from combat range. It was very effective against the Panther’s front turret and from the side, however. The high U.S. tank losses in the Battle of the Bulge against a force largely of Panther tanks brought about a clamor for better armor and firepower. At General Eisenhower’s request, only 76 mm M4 Shermans were shipped to Europe for the remainder of the war. Small numbers of the M26 Pershing were also rushed into combat in late February 1945. A dramatic newsreel film was recorded by a U.S. Signal Corps cameraman of an M26 stalking and then blowing up a Panther in the city of Cologne, after the Panther had knocked out two M4 Shermans. Production of Panther tanks and other German tanks dropped off sharply after January 1945, and eight of the Panther regiments still on the Western Front were transferred to the Eastern Front in February 1945. The result was that for the rest of the war during 1945, the greatest threats to the tanks of the Western Allies were no longer German tanks, but infantry anti-tank weapons such as the Panzerschreck and Panzerfaust, and infantry anti-tank guns such as the ubiquitous 7.5 cm Pak 40, and mobile anti-tank guns such as the Marder, StuG III, StuG IV, and Jagdpanzer. A German Army status report dated March 15, 1945 showed 117 Panthers left in the entire Western Front, of which only 49 were operational, ). Further development Panther II This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (September 2009) Panther II on display at Patton Cavalry and Armor Museum, Fort Knox, KY. The turret on display was not originally fitted to this hull and was installed later. The early impetus for upgrading the Panther came from the concern of Hitler and others that the Panther lacked sufficient armor. Hitler had already insisted on an increase in armor to the Panther once, early in its design process in 1942. Discussions involving Hitler in January 1943 called for a Panther tank with further increased armor, initially referred to as Panther 2 (it became the Panther II after April 1943). This upgrade increased the glacis plate to 100 mm (3.9 in), the side armor to 60 mm (2.4 in), and the top armor to 30 mm (1.2 in). Production of the Panther 2 was slated to begin in September 1943. In a meeting on February 10, 1943, further design changes were proposed – including changes to the steering gears and final drives. Another meeting on February 17, 1943 focused on sharing and standardizing parts between the next Tiger tank and the Panther 2, such as the transmission, roadwheels, and running gear. Additional meetings in February began to outline the various components for the Panther 2, including use of the 88 mm L/71 KwK 43 gun. In March 1943, MAN indicated that the first Panther 2 prototype would be completed by August 1943. A number of engines were under consideration for use in the Panther II, among them the new Maybach HL 234 fuel-injected engine (900 hp operated by an 8-speed hydraulic transmission). Thus, plans to replace the original Panther design with the Panther II were already underway before the first Panther had even seen combat. From May to June 1943, further work on the Panther II ceased at the various manufacturers gearing up to produce the tank as the focus was shifted to expanding production of the original Panther tank. It is not clear if there was ever an official cancellation of the Panther II – this may have been because the Panther II upgrade pathway was started originally at the insistence of Hitler. The direction that the Panther II design was headed would not have been consistent with Germany’s need for a mass-produced tank, which was the goal of the Reich Ministry of Armament and War Production. One Panther II chassis was completed and eventually captured by the U.S.; it is now on display at the Patton Museum in Fort Knox. An Ausf G turret is mounted on this chassis. Panther Ausf. F After the Panther II project died, a more limited upgrade of the Panther was planned, centered around a re-designed turret. The Ausf F variant was slated for production in April 1945, but the war ended these plans. The earliest known redesign of the Panther turret was dated November 7, 1943 and featured a narrow gun mantlet behind a 120 mm (4.7 in) thick turret front plate. Another design drawing by Rheinmettall dated March 1, 1944 reduced the width of the turret front even further; this was the Turm-Panther (Schmale Blende) (Panther with narrow gun mantlet). Several experimental Schmalturm were built in 1944 with modified versions of the 75mm KwK 42 L/70, which were given the designation of KwK 44/1. A few were captured and shipped back to the U.S. and Britain. One is on display at the Bovington Tank Museum Model of Panther Ausf. F with proposed Schmalturm The Schmalturm had a much narrower front face of 120 mm (4.7 in) armor sloped at 20 degrees; side turret armor was increased to 60 mm (2.4 in) from 45 mm (1.8 in); roof turret armor increased to 40 mm (1.6 in) from 16 mm (0.63 in); and a bell shaped gun mantlet similar to that of the Tiger II was used. This increased armor protection also had a slight weight saving due to the overall smaller size of the turret. The Panther Ausf F would have had the Schmalturm, with its better ballistic protection, and an extended front hull roof which was slightly thicker. The Ausf F’s Schmalturm was to have a built-in stereoscopic rangefinder and lower weight than the original Panther turrets. A number of Ausf F hulls were built at Daimler-Benz and Ruhrstahl-Hattingen steelworks; however there is no evidence that any completed Ausf F saw service before the end of the war. Proposals to equip the Schmalturm with the 88mm KwK 43 L/71 were made from January through March 1945. These would have likely equipped future German tanks but none were built, as the war ended. E-50 The E series of tanks E-25, E-50, E-75, E-100 (the numbers designated their weight class) – was proposed to further streamline production with an even greater sharing of common parts and simplification of design. In this scheme, the Panther tank would have evolved into the E-50. A conical spring system was proposed to replace the complex and costly dual torsion bar system. The Schmalturm would have been used, likely with a variant of the 88 mm L/71 gun. Derived vehicles Bergepanther on display at Saumur armour museum Jagdpanther – heavy tank destroyer with the 88 mm L/71 Befehlspanzer Panther – command tank with additional radio equipment Beobachtungspanzer Panther – observation tank for artillery spotters; dummy gun; armed with only two MG 34 Bergepanther – armored recovery vehicle Postwar and foreign use This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (August 2009) Although a technologically sophisticated vehicle for its time, the Panther’s design had only a very limited influence on postwar tank development. The Panther was (arguably) an early precursor to the modern Main Battle Tank, but apart from this debatable distinction only the French postwar AMX 50 tank prototype was directly and significantly influenced by it. While the AMX 50 never actually entered series production, the French did produce a modified version of the Panther’s 75 mm KwK 42 L/70 gun, as the 75 mm DEFA and CN75-50 gun. This gun equipped the first iteration of the AMX 13 light tank as well as the EBR armored car, and was also used by the Israeli M50 Super Sherman.[citation needed] The Panther itself also saw some limited use outside the German military, both before and after 1945. During the war, the Red Army employed a number of captured Panthers. These were repainted with prominent Soviet emblems and tactical markings to avoid friendly fire incidents. The Red Army still used a few Panthers as late as spring 1945.[citation needed] During March-April 1945 Bulgaria received 15 Panthers of various makes (D. A and G’s) from captured and overhauled Soviet stocks, they only saw limited (training) service use. They were dug down, with automotive components removed, as pillboxes along the Bulgarian-Turkish border as early as the late 40′s. The final fate of these pillbox Panthers is unknown but sources indicate that they were replaced and scrapped sometime during the 1950′s. One captured vehicle (nicknamed “Cuckoo”) also saw service with the British Coldstream Guards for some time. Japan reportedly bought a single Panther Ausf. D for reverse engineering purposes in 1943. However the tank apparently never actually made it to Japan. The Panther’s sloped armour and turret design nevertheless did influence the design of Japans last wartime tank prototypes; the medium Type 4 Chi-To and heavy Type 5 Chi-Ri. After the war, France was able to recover enough operable vehicles and components to equip the French Army’s 503e Rgiment de Chars de Combat with a force of fifty Panthers. These remained in service until about 1950, by which time they had all been replaced by French-built ARL 44 heavy tanks. In 1946, Sweden sent a delegation to France to examine surviving specimens of German military vehicles. During their visit, the delegates found a few surviving Panthers and had one shipped to Sweden for further testing and evaluation. Testing continued until 1961. The tank is currently on display in the Deutsches Panzermuseum in Munster. Surviving vehicles In working order. Military Vehicle Technology Foundation, USA. Ausf. A Muse des Blinds, France. Ausf. A Deutsches Panzermuseum, Munster, Germany. Ausf. A Command Tank Wehrtechnische Studiensammlung, Koblenz, Germany. Ausf. G. Completed after the war in the Panther factory under supervision by UK REME engineers, used for tests Friedrich Christian Flick Private Collection, Germany. Ausf. G. Completed after the war in the Panther factory under supervision by UK REME engineers, used for tests Kubinka Tank Museum, Russia. Ausf.G Not running, more or less complete. Wilhelmina park, Breda, The Netherlands. The only known complete surviving Ausf. D. This tank was donated by the Polish 1st Armored Division after liberating Breda. It was restored in 20042005 for static display by Kevin Wheatcroft in exchange for automotive components. Panzermuseum Thun, Thun, Switzerland. Advertised as an Ausf. D/G hybrid, with a D hull and G turret. There are many questions surrounding this vehicle. The turret has a replacement sheet metal mantlet, vaguely resembling a late Ausf. G mantlet, with no ports for gunners sight or coaxial MG. The pistol port on the turret rear indicates an Ausf. A or early Ausf G. The hull with the “letterbox” MG slot indicates an Ausf. D or early Ausf. A. The turret and hull numbers could help identify the correct model designation for the hybrid but neither of the numbers have been made public. Kevin Wheatcroft, private collector, UK. One being restored. Early Ausf. A (DEMAG production). Two more to follow, one Ausf. A and one Ausf. A converted to a D. The restored Panther ausf A on display at the Canadian War Museum in Ottawa. Canadian War Museum. In January 2008 a partially restored Panther Ausf. A was put on display. It had been donated to the museum from CFB Borden, which acquired it following V-E celebrations in May 1945. It had spent two years in restoration prior to being put on public display. Rex & Rod Cadman Collection, UK. Ausf. A US Army Ordnance Museum. Ausf. A Sinsheim Auto & Technik Museum, Sinsheim, Germany. Ausf. A Muse des Blinds, Saumur, France. Ausf. A Muse des Blinds, Saumur, France. Ausf. A Mourmelon-le-Grand, France. Ausf. A Muse des Blinds, Saumur, France. Ausf. G Bovington Tank Museum, UK. Ausf. G. Completed after the war in the Panther factory under supervision by UK REME engineers, used for tests. Panther in the river at Houffalize, 1945 Houffalize in the Ardennes region of Belgium. A Panther Ausf. G can be found in the village. It fell into the river during the Battle of the Bulge and was later retrieved as a memorial. US Army Ordnance Museum. An Ausf. G with one of two surviving turrets with the flattened lower (‘chin’) mantlet National War and Resistance Museum, Overloon, Netherlands. Ausf. G General George Patton Museum, Fort Knox, KY, USA. Ausf. G General George Patton Museum, Fort Knox, KY, USA. Panther II chassis with a late Ausf. G turret, the second surviving turret with the flattened lower (‘chin’) mantlet. Restored with many components from the Ausf. G in the Museum collection. Wrecks. Sinsheim Auto & Technik Museum, Sinsheim, Germany. Ausf. A August 1944 Museum, Falaise, France. Ausf. A Kevin Wheatcroft, private collector, UK. Ausf. A. Will be restored. All components needed are already sourced or remanufactured. Kevin Wheatcroft, private collector, UK. Ausf. A. Will be restored to an Ausf. D. All components needed are already sourced or remanufactured. Grandmenil, Belgium. Ausf. G Celles, Houyet, Belgium. Ausf. G Detailed specifications Three-view profile of Pzkpfw. V Ausf. A. Copyright Giovanni Paulli. Crew: 5 Dimensions Length including gun: 8.66 m hull only: 6.87 m Width: hull: 3.27 m, with skirt plates: 3.42 m Height: 2.99 m Combat weight: Ausf. D 43.0 t Ausf. A 45.5 tonnes Ausf. G 44.8 t (46.58 t with steel road wheels) Performance Road speed: 55 km/h at 3,000 rpm (46 km/h at 2,500 rpm) Road range: 200 km Suspension and tracks type: dual torsion-bar Shock absorbers: on 2nd and 7th swing arms on either side Track type: Kgs 64/660/150 du…
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RC Helicopter Micro Mosquito
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Syma S107/S107G R/C Helicopter *Colors Vary $19.99 This Brand New 3 Channel Gyro mini Metal rc helicopter is 1 of the world’s newest, smallest and lightest RC Helicopter you can get! At approx. 7.5″ long, it easily fits in the palm of your hand and is fully functional, equipped with latest Gyroscope technology, which makes this helicopter an instant hot seller in the RC World. This mini Gyro Metal helicopter charges directly either from the USB ca… |
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SYMA S108G 3.5 CH Infrared Mini Radio Controlled Marine Cobra Helicopter Gyro $21.00 This is the Newest Mini Helicopter by Syma. The Electric Co-axial Micro helicopter series is suited for both the beginner and the advance pilot, anyone can enjoy it with the first flight…. |
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Falcon X mini indoor 3 Channel Co-Axial RC Helicopter with Gyro $19.99 #Color Chosen at random from Yellow, Blue or Red Feature: |
Axial Brushless Motor
Axial Brushless Motor
Fans and Blowers
Commonly available practical methods of plants ventilation are:
* Exhaust fans or Power Roof Ventilators (PRVs).
To do a satisfactory job of eliminating excessively hot air, it is usually essential to have powered wall and/or roof exhausters. These fans should also help to control air pressure within the building whether it be negative or positive pressure.
* Supply Fans or PRVs.
A large number of buildings use exhaust PRVs to exhaust fumes, smoke, dust or other contaminants unavoidable in the operation of the business. As a result, these buildings are frequently under a severe negative pressure. The solution to the problem of this kind is usually found in the use of supply fans or “make-up” air ventilators.
* Air Circulators.
If the exhaust and supply air requirements of a building have been carefully engineered and installed, and there continues to be a high instance of worker discomfort, the problem usually relates to the matter of air circulation. In this way, in addition to amximum benefit from the fresh, cooler air, occupants receive the added comfort of air circulation over their bodies and they are not adversely affected by the superheated air being exhausted from the building.
Air moving fans and blowers utilize power from a motor to generate a volumetric flow of air at a given pressure, and are considered low-pressure air pumps. A propeller converts torque (turning force) from the motor (typically permanent split capacitor AC induction motors or brushless DC) to increase static pressure across the fan rotor and to increase the kinetic energy of the air particles.
Fans are classified into propeller, tube axial and vane axial styles, and each type has different characteristics and different areas of application. Propeller fans ususally consist of only a motor and propeller and therefore are the simplest among all. Tube axial and vane axial are similar to propellers but has a venturi around the propeller to reduce the vortices. Vane axial fans are equipped with vanes that trail behind the propeller in the airflow to straighten the swirling flow.
The flow and pressure properties are the main differences between a fan and a blower. While fans deliver air in an overall direction that is parallel to the fan blade axis, blowers deliver air in a direction that is perpendicular to the blower axis. Hence, fans can be configured to deliver a high flow rate, working against low pressure while blowers to deliver a relatively low flow rate against high pressure. Centrifugal blowers can be squirrel cage type, have a forward curved wheel or a backward curved wheel.
Another major difference between the fans types is in the mechanism regarding restriction to the air-flow. In a blower, it has an opposite effect on the same motor driving a fan blade. For instance, the load on the motor decreases when the motor is driving a squirrel cage blower. As the system becomes clogged, the blower speeds up. On the other hand, the load on the motor increases and the fan slows down as the airflow system becomes clogged with fan blades.
Additional information can be found at the Tenderall Fan web site http://www.tenderall.com.
Oleg Chetchel
Industrial Equipment Designer
Tenderall Fan Co.
http://www.tenderall.com/blower/index.html
http://www.tenderall.com/ventilator/index.html
About the Author
Oleg Chetchel
Ventilation Equipment Designer
Tenderall Fan Co.
http://tenderall.com
Axial Scorpion Rock Crawler with Brushless Motor, 50 MPH!
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Titan 380 Motor 18T: 1/16 $10.12 Motor – 1/16 Titan 380 (18 Turns)… |
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BRUSHLESS PERM MAGNET MOTOR DES-OP $165.00 Written for electrical, electronics, and mechanical engineers responsible for designing and specifying motors, the book provides details of brushless DC and synchronous motors, as well as both radial and axial motor topologies. Beginning with a discussion of the fundamentals of generic motor design, it logically progresses to a set of more advanced, yet easily understandable, concepts for designin… |
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Axial Flux Permanent Magnet Brushless Machines $118.05 Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. This timeless and revised second edition deals with the analysis, construction, design, control and applications of AFPM machines. The authors present their own research results, as well as significant research contributions made by others…. |
Axial Remote Control
Axial Remote Control
Micro Super V3 RC Helicopter (3-Channel Co-Axial)
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iPazzPort 2.4GHz Mini Wireless Fly Air Mouse Keyboard with IR Remote $32.99 Ship from China by USPS, normally 7 to 12 business days to deliver. Rechargeable Li-ion batteries: Last longer up to two weeks between charges. Short recharge time: Around two hours can fully charge the battery. 2.4G wireless: Enjoy long-range wireless control from up to 10 metre (33 feet) away. Backlighting: Makes text entry effortless even in low light conditions. Mini USB dongle, inside case. I… |
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Laptopmate OEM iPazzPort Mini Wireless Air Fly Mouse Keyboard with IR Remote – Black $39.77 Introduction:iPazzPort Voice Mini Wireless Handheld Keyboard consists of Keyboard, mouse touchpad, laser pointer. It is designed small and portable and widely used for:1.Teaching, training, lecturing. You can sit more comfortably on your sofa and remotely control your computer, instead of sitting in front of the computer. (Max wireless operation distance: 10M/33 feet)2. Controlling home electric a… |
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S107G 3 Channel Mini Indoor Co-Axial Metal RC Helicopter w/ Built in Gyroscope (Red & Yellow) Set of 2 $40.62 Feature: Miniature size & light weight. Super wide infrared control miniature design for indoor flying 19cm long and weighing an incredible 34 grams |
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Syma S107/S107G R/C Helicopter – Blue $19.99 Syma S107G is equipped with a 4-in-1 infra-red receiver (Gyro, ESC, Mixer, Receiver). This palm size S107 Toy Helicopter (18.5cm long) comes with Aluminum Frame and a Great detail canopy, it doesn’t look like a toy, but a very serious Helicopter. It is able to move in 3 Direction base on the 3 Channels, anyone can hover it easily. Since it is made with Aluminum Frame, very light weight and almost … |
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Syma S109G Apache AH-64 3.5-Channels Mini Indoor Helicopter $21.99 The Syma S109G is a palm size 3-Channels Helicopter, it has a youngest brother in the Syma Apache line. The S109G has a Co-Axial structure which is specially made for first time flyers. The S109G is built with thick plastic body which always survives in crashes. The Syma S109G is equipped with a 4-in-1 receiver (Gyro, ESC, Mixer, Receiver), allows the helicopter to move in all directions. This hob… |
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The Gyro Star S107 3 Channel Mini Indoor Co-Axial Metal RC Helicopter w/ Built in Gyroscope (Blue) $39.99 The Gyro Star S107 is a high quality 3 channel mini indoor co-axial helicopter w/ built-in gyro and a metal frame. This model is miniature in size and its light weight makes it incredibly portable so you can take it anywhere you go. It also offers a wide infrared control and a design that is customized for indoor flying. For being only 19cm in length and weighing in at only 34grams, this mini heli… |
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Electric Auto Repair
Electric Auto Repair
All General Automotive Repairs in One Auto Repair Shop in Bradenton 34207
It is not only convenient but also cost effective to centralize all general automotive repairs, including all minor repairs and major repairs, in one full service auto repair shop in Bradenton 34207. The vehicle owner can swing huge discounts in exchange for loyalty. It is, however, important to ensure that the chosen auto repair shop in Bradenton 34207 has the highest expertise.
One way of determining the abilities of an auto service shop is to find out if it services the most well known vehicle brands such as Cadillac, Chevrolet, GM, Pontiac, Oldsmobile, Ford, Lincoln, Mercury, Dodge, Jeep, Plymouth, Chrysler, Daewoo, Audi, BMW, Mercedes, Jaguar, Volkswagen, Volvo, Acura, Honda, Lexus, Scion, Toyota, Nissan, Infiniti, Mitsubishi, Hyundai, Mazda and Suzuki.
The auto service shop should also supply exclusively genuine replacement automotive parts such as AC Delco, Bosch, Remy, Motorcraft, Mopar, Goodyear, Dayco, Echlin, Standard, Cardone, Autolite, NGK, Akebono, Nipedenso, and Denso. After all, any savings from fake replacement automotive parts would be useless and would even endanger the vehicle owner.
The mechanics of the auto service shop should have expertise in all aspects of auto maintenance and repair including engines, engine rebuild, engine replacement, brakes, tractions control systems, antilock brake systems (ABS), transmission services, computer diagnostics, computer reprogramming, electronic steering, power steering, power brakes, power windows, power convertible tops, power sunroofs, power locks, radiators, cooling systems, alternators, hoses, belts, timing belts, electrical troubleshooting for all types of electrical shorts, body systems, front suspension, rear suspension, air suspension, air bag systems, anti theft systems, remote starters, key reprogramming, auto air conditioner (A/C) repair, oil change service, transmission flush and repair of oil leaks.
A vehicle owner who centralizes all general automotive repairs, including all major and minor repairs, in the best possible full service auto repair shop with an expert mechanic in Bradenton 34207 will always be able to avail of top rate maintenance and repair services at the most reasonable rates.
About the Author
ABC Autotech
Richard Borovicka
4411 30th St. West
Bradenton, FL 34207-1324
Phone: (941) 755-0112
Fax: (941) 755-8150
Email: aautotech@tampabay.rr.com
Website: www.abcautotech.com
Hi-Line Auto Electric – Auto Repair in Burien, WA
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Axial Lead Capacitor Polarity
Axial Lead Capacitor Polarity
Defensive Mechanism of S.s
Defensive Mechanism of S.S
CIRCUIT BREAKER:
I. Introduction
The primary functions of a circuit breaker are interrupting short circuit current, carrying normal currents, switching ON and OFF normal loads, and providing necessary insulating between live parts and earthed parts. The maintenance problems involved with bulk oil circuit breakers were immense. Minimum Oil technology had replaced bulk oil technology during 1950’s. Similarly the air -blast technology was developed for obtaining higher performance characteristics. However, the air -blast breakers are quite expensive, and their operation and maintenance cumbersome. Hence and need was felt during 1960’s for reduced maintenance.
SF6 was first obtained from Fluorine and Sulphur in 1900 by M/s. H.MOSSAN and PLEBEAU. Behavior of SF6 in Electrical field was studied by M/s. H.G. PQLLOCK and P.S. COOPER in 4936 known for over two decades, perfection on commercial exploitation was attained during 1960’s. This development made it possible for SF6 gas at low pressure to be used in BIN circuit breakers for insulating and are’ quenching purposes, Some of the outstanding properties of SF 6 gas which make its use ideal in EHV circuit. breakers are:
1. Inertness
2. Non-toxicity
3. Electro negative nature
4. High dielectric strength
5. Unique are quenching property
6. Chemical and thermal stability
7. Good Thermal conductivity
8. Non corrosiveness
9. Non-Flammability
The combined electrical, physical, chemical and thermal properties of SF6 offer the following outstanding features when used in power circuit breaker.
1. Safety
2. Size reduction
3. Weight reduction
4. Simplified design
5. High degree of reliability
6. Switching of capacitive currents without restrike
7. Very tow noise level
8. Easy for handling
9. Easy for installation
10. Maintenance free service
2. Properties of Sulphur Hexafluoride (SF6 )
a) Physical properties:
SF6 is a colorless, odorless and non-flammable gas. The fluorine atoms are placed at the corners of a regular octa-hedran with the sulphur atom centrally placed at a distance of 1.58 angstrom units. The bonds are predominantly covalent and the dissociation equation is
SF6 –à SF5 + F __________
The decomposition potential is 15.7 ev. SF6 gas is a very heavy gas and its density is approximately 5.5 times that of air. It is highly stable. It is more compressible than air and follows the law of perfect gases.
b)Electrical properties:
The di-electric strength of SF6 gas is 3 times that of air at atmospheric pressure and is only marginally reduced by the presence of air as impurity. The dielectric strength increases with increasing pressure. At a pressure of three bars, the dielectric strength becomes equal to that transformer oil. The size and electro negative nature molecule explain this strength. The molecule provides a large electron collision diameter. This results in capture of electrons preventing them from attaining sufficient energy to create additional .current carrying particles. SF6moiecuie also has the ability to store energy in the vibrational and electronic’ levels of the molecule there by forming stable ions of low mobility.
The dielectric strength of SF6 remains unaltered over a wide range of frequencies. since SF6 has no dipole moment, the dielectric constant does not vary with frequency. AT 27.30c and atmospheric pressure the dielectric constant is 1.00191 and loss angle is 2 x 10-7.
The dielectric properties of SF6 remain unchanged even at low temperatures. Unlike solid insulation materials an electrical breakdown in SF 6 gas does not result in permanent deterioration of its properties. Break down in all filled equipment may result in enormous increased of pressure due to gas formation but such hazards do not exist in the case of SF6 filled equipment.
c)Arc quenching properties:
The ability to quench arc is unique to SF 6. This results in the high dielectric strength of the gas and the very rapid recovery of dielectric strength after arcing occurs. SF6 is approximately 100 times more effective in this respect than air under similar conditions. The low arc-time constant and its capacity to absorb free electrons due to electro negative nature makes it an excellent medium for arc interruption. The complex molecular motion of SF6 enables it to absorb electric energy and form stable negative ions. Its tendency to form negative ion around current zero results in the fast disappearance of electrons liberated during arcing. Unlike oil, arcing in SF6 will produce no carbon deposits or carbon tracking.
The electro-negative property of SF6 may be due to several factors, including its large collision diameter. If stray electron electric field can be absorbed before they attain sufficient energy to create additional current carrying particles though collision, the breakdown can be slowed or even stopped. The large collision diameter of SF6 molecule assists in capturing these electrons. energy can be stored in the vibration levels of the SF6 atom, forming stable negative ions of low mobility. Thus the gas is electronegative in nature and shows .great electron binding capacity. Hence SF6 gas displays splendid arc-extinguishing performance .
The arc time constant is directly proportional to the radius of arc makes it possible to have large number of breakings at full capacity of the breaker. The characteristic curve of the arc is such that the extinction power b low. In a typical case where the extinction power was of the order of 20 KW for an SF6 breaker, the corresponding value of an air blast breaker was in hundreds of KW.
Some ion formation process with SF6 are :
Resonance capture : SF6 + e -à (SF6) – SF5- + F
Positive ion formation : SF6 + e -à (SF6+) + 2e -SF5- + F + 2e-
Excitation & dissociation : SF6 + e -à (SF6-) + e -SF5- + F + e
Positive & negative ion formation: SF + e -à (SF6-) + e -SF5 + F -+ e
d) Heat Transfer characteristics:
SF6 has excellent heat transfer characteristic, an important criterion for gaseous dielectric in power applications. The higher molecular weight together with low gaseous viscosity of SF6 enables it to transfer heat by convention more effectively than the common gases. The co-efficient of heat transfer of SF6 is approximately 2.5 tip1es that of air under the same conditions. Hence when the breaker is energized, the temperature rise small.
e)Wide temperature range :
SF6 in the gaseous state follows the ideal gas laws fairly closely. Consequently the pressure change is only moderate for a considerable change in temperature. The low sublimation points of SF6 assures greater dielectric strength even at low temperature the liquification temperature is —270C at a pressure of 12 Kg / sq. cm. Hence no heater is necessary.
f)Toxity :
SF6 is a non-toxic gas and produces no poisonous effect on human body. But the decomposition products produced by the discharge (SF4, SF2, S2, F2 etc.) are harmful. These products are minimized by controlling of moisture in the interrupter and by absorbing the decomposition products by synthetic zeolite.
g)Chemical and Thermal Stability:
SF6 gas is inert and it is one of the least reactive substance known under normal operating conditions. It may be heated in quartz to 5000C without under going any decomposition. SF6 does not react with water, acids and alkalis. Tests conducted have shown practically no corrosion for various metals exposed to SF6
h) Various constants :
Some of the outstanding properties of SF6 which makes it ideal for high voltage power applications are:
Molecular weight .. 146.05
Sublimation point at 1 atm .. 63.9°C
Density of gas at 21.19 C at 1 atm .. 6.139
Viscosity liquid at 13.52°C .. 0.305
Gas at 31.16°C .. 0.0157
Critical temperature etc. .. 318.80
Critical pressure bars .. 37.772
Critical volume cu.metre / g .. 1.356
Dielectric strength reI N2 = al at 50 Hs -1.2 Mhs .. 2.3 -2.5
Dielectric constant at 25°C 1atm .. 1.002049 ‘
Thermal conductivity at 30°C, Cal / Sec. -on °C .. 3.36 x 10-5
3. Breakdown phenomenon in SF6 :
Breakdown in gases takes place when the free electrons gain sufficient kinetic energy Under the influence of an electric field and collide with neutral gas molecules liberating electrons from their outer shells. A chain reaction like this results in an electron avalanche. In the case of electro-negative gases like SF6 this mechanism is slightly modified. The free electrons get attached to molecules forming negative ions. SF6 + e Z SF6 -e. This negative ions are too massive to produce collisional ionization. This attachment represents an effective way of removing electrons which would have otherwise contributed to an electron avalanche. This particular behaviors gives rise to very high dielectric strength for electronegative gases.
The breakdown voltage of an electro-negative gas in a uniform field is a simple function of the product of pressure and spacing. the breakdown characteristics in non-uniform fields will be different because ionization may be main aimed locally due to the presence of regions of high stress. This is the corona effect. This may be due to surface roughness, sharp comers, floating conducting or semi-conducting particles. In SF6 equipments special care is taken to ensure that such sharp points do not exist in the breaker so that a fairly uniform field distribution can be achieved.
4. Principles of interruption with SF6 :
Techniques employed for interruption with SF6 can be classified into two :
a) Double pressure system.
b) Single pressure system.
The latter can be further classified as double flow fixed nozzle and single flow series piston breakers.
a)Double pressure system:
The functions of insulation and interruption are performed in separate chambers. SF6 at a pressure of 14 Kg/sq. cm. is stored in a high pressure chamber. This is used for quenching the are SF6 at low pressure (2.5 to 3.5 Kg/sq. cm.) provides the insulation. When the contacts separate under fault, gas at high pressure is forced into the arcing region and then it follows in to the low pressure region. The gas thus exhausted in to the low pressure region is compressed again and returned to the high pressure reservoir. The arcing takes place between the arcing tip and arcing ring thus relieving the contact area from the stresses of arc. A filter with actual alumna is kept at the intake of the compressor so that all the decomposition products of gas can be absorbed before re-circulating in to the system. A thermostatically controlled heating system will be provided in the high pressure reservoir to prevent condensation of gas at low temperature.
b) Single pressure system :
In this case SF6 at low pressure (3 to 6.5 Kg/sq.cm.) provides the insulation and the energy for interruption. The breaker chamber consists of the fixed and moving contacts, and the piston arrangement in the puffer type fixed contact. As the moving contact separates under fault, the piston moves forward with high speed. This compresses the SF 6 inside the hallow fixed contact and forces the gas into the arc resulting in quenching. The force with which the gas could be blast depends on the design of the piston arrangement and the energy of the control mechanism.
A further improvement is the Magnetic puffer type breakers where the operating force on the moving contact rod is increased, by magnetic repulsive force. The short circuit current is passed through a set of coils fixed on the support of the moving contact fed. A secondary short circuit ring is positioned and magnetically coupled with primary winding. This ring acts as piston as well. This interaction between the. two fields produces a repulsive force and it pushes the moving contact rod forward. The addition of this simple magnetic drive mechanism improves the interrupting capabilities of the breaker.
The single pressure system has an inherent advantage of simplicity in construction. It needs no additional compressor as required in double pressure system. The manufacturing cost of puffer type equipment is lower.
5. Construction:
The arc extinguishing system employs a synchronized double flow single pressure puffer type design. This leads to a simple construction.
The SF 6 circuit breaker mainly comprises of the following:
1. Breaker poles it.
2. Base tube and mechanism box
3. Control unit
4. Air compressor electro-hydraulic operating mechanism
1.Movable Cylinder(Puffer cylinder) 2.Moving Contact
3.Fixed Contct 4.Insulating Nozzle
5.Fixed Piston 6.Gas Trapped in before compression
7.Compressed gas between 1 & 5
8.The arc-being extinguished by puffer action
5.1.Breaker Pole:
The primary functions of a circuit breaker are carried out of breaker pole. The breaker pole consists of interrupter unit and support insulator.
The interrupter unit consists of fixed contact tube, guide tube, moving contact tube, puffer or blast cylinder and piston. The fixed contact tube is connected to the top terminal via. Contact support.
The guide tube is fastened to the lower terminal. The other ends of the fixed contact tube and guide tube which are subjected to arcing during the arc interruption are provided with arc quenching nozzles. the nozzles are made up of graphite materials which keeps the contact wear to minimum. The moving contact tube consists of spring loaded finger contacts arranged in the form of a ring. The front end of the moving contact tube is provided with an arc resistance insulating ring and arcing ring of high arc resistant materials
The blast cylinder which is made up of high arc resistant insulating material and the moving contact tube are rigidly coupled to each other and connected to the operating rod in the supporting insulator. The blast piston which is made up of aluminum is fastened to the lower terminal pad. The fixed contact tube, guide tube, moving contact tube, blast cylinder and blast piston are “all housed inside a porcelain ,insulator. When the circuit breaker is in close position current flows from top terminal to bottom terminal through contact support, fixed contact tube, moving contact tube and guide tube.
The support insulator apart from supporting the interrupter unit provide insulation between live parts and earthed parts. It houses the operating rod (insulated), one end of which is connected to the interrupter unit and the other end is connected to the mechanism.
5.2. Base Tube mechanism box:
The base tube which supports the breaker pole and the mechanism box acts as a local air reservoirs. The mechanism box enclosed electromagnetic valve, closing coil, trip coil and operating cylinder. Lower mechanism case encloses the complete lever system to transmit the operation force from the mechanism box to the breaker pole.
5.3.Control Unit :
This accommodates the gas pressure switches, gas density detector, gas pressure gauge, air pressure gauge, air valve heater, auxiliary relays, terminal blocks, etc. for electrical and pneumatic control and monitoring of the breaker. The control devices of the air and SF6 gas systems are common for 3 poles of the breaker.
5.4. Compress
Since the operating energy requirement is greater the MOCBS either air compressor or electro-hydraulic operating mechanism is used.
6. The principle of Arc extinction:
When the circuit breaker is in closed position the moving contact assembly bridges the fixed contact tube and the guide tube. When an opening operation is initiated, the blast cylinder moves towards the stationary blast piston so that the SF6 gas in the blast cylinder is compressed to a pressure required to quench the arc. The gas compressed during the above process is released only when the contacts are separated with moving contact assembly acting as a slide valve. At the instant of contact separation, arc strikes between the front end of the arc quenching nozzle of the fixed contact tube and the arcing ring of the moving contact tube. The compressed gas in the blast cylinder is released in the break radically as the contacts are separated. As the moving contact assembly moves further, the arc between the front end of the fixed contact nozzle and the arcing ring of the moving contact is transferred from the arcing ring of the moving contacts of nozzle of the guide tube , by gas jet and its own electrodynamics forces. the arc is further elongated by the gas flow axially into the nozzles and safety extinguished. While the arc is being interrupted, the blast cylinder which is made up of arc resistant insulating material enclosed the arc quenching assembly, there by protecting the porcelain insulator from arcing effects. After arc extinction, the moving contact assembly and blast is free of any parts of the chamber which may have a bridging effect or influence the electric field distributor.
7. Operation principles:
7.1. Opening operation:
When the trip coil is energized, the space of pilot valve is filled with compressed air and the charging valve moves to right. The space in the operating cylinder is filled with compressed air from the air received and the operating piston is rapidly driven to the left. the operating rod connected to the operating piston is pulled in the opening direction to drive the puffer cylinder at the high speed through the insulated operating rod in the supporting insulator. the SF6 gas in the puffer cylinder is compressed and the SF6 gas blast extinguishes the arc generated between the moving and stationary contacts.
Simultaneous with the opening operation, the cam rotates and causes the electromagnet valve to return to its original position. As a result, compressed air in the space of pilot valve is exhausted into atmosphere and the charging valve is reset to the original piston. As the open state is retained by the link mechanism attached to the end of the operating piston.
7.2. Closing operation:
When the closing coil is energized, the arc nature is made to rotate causing the hook to be disengaged. Thus the sector line rotates to release the roller and the operating piston is driven in the closing direction by the force of the closing spring, upon completion of closing, the link mechanism is held in a state to be ready for the subsequent opening operation.
8. Caution :
When operating the breaker observes the following:
I)Keep correct SF6 gas pressure and operating air pressure as specified.
2)Operate the stop valves properly.
3)Do not allow ingress of moisture and dust into the SF6 gas supplying point.
4)Do not pump the gas piping and air piping with any object.
5)Do not damage the gasket and seal face on the leakage tight joint in the gas and air system.
6)When opening the circuit breaker by the manual handle. ‘
a) confirm that the main circuit is not energized.
b) Be sure to turn off the control power supply.
c) Confirm that compressed air in receivers is released.
d) Confirm that manual operating rod and handle are removed before changing the receiver with compressed air.
7)Do not operate any part other than the manual operating handle before filling SF6 gas at the rated pressure. Do not fill compressed air before filling SF6 gas.
8)When checking interior parts of interrupter, blow air into the system for sufficiently long time and confirm that sufficient supply of air is available before starting any work.
9.Gas Leak Detection:
If the gas leaks through any point, this can result in reduction of pressure and consequent loss of insulation properties Gas Leak detection is done with the help of a halogen torch type detector. The detector works on the principle that SF6 absorbs a certain number of electron when passed through an atmosphere where free electrons flow. The free electrons are generated with in the sector by a small radio active source in the presence of a carrier gas. these electrons are collected at the detector anode and give a small base line current which is amplified. When the probe of the detector is kept near the joints of the SF6 filled equipment and if SF6 leaks out there will be variation in amplified valve of current due to electron absorption by SF6. The variation can be directly calibrated to indicate the magnitude of the leak.
9.2. Detention of presence of conducting particles:
This is done by conducting a dielectric test when the test voltage is applied there will be an internal corona if metallic particle or sharp comers are present. The presence of internal discharges is located with the help of an ultrasonic detector which is very sensitive in detecting noise due to internal corona. The sector translates the ultrasonic vibrations into audible frequencies and directly indicates the intensity of sound in decibels. The probe is pressed firmly against the grounded enclosure tube while the conductor is energized at varying AC I DC voltage. If the noise disappears at low voltage, appears at some intermediate voltage and the intensity continues to increase, it is certain that the noise is due to internal corona. It has also been observed that in some cases the small sharp potty branched in areas of high dielectric stress get burnt or the particles driven to low stress areas. The effect of conducting particles on the break down strength of SF6 is more serious for power frequency voltage test than for impulses voltage.
10. Performance of SF6 Breaker:
SF6 gas circuit breaker combines the advantageous features minimum oil and air blast breakers and exhibits a number of additional advantages over both.
1)It is possible to have large number of breaking operations near full breaking capacity with out any undue wear.
2)Because of the fast recovery of dielectric strength across the parting contacts during interruption.
a) These breakers are restrict free while switching of capacitive currents.
b) These breakers are incentive to short time faults and are capable of breaking at every high values of RRRV and
c) These breakers are suitable for multi-short re closing with out any reduction in breaking capacity
3)There is no necessity to change any parts in the breaking chamber even after a period often years of service in the actual system. This means that there are practically no problem of maintenance for SF6 breakers.
4)The operation is noiseless since the gas is used in a closed circuit. There will be no discharge of arc products into atmosphere.
5)Puffer type breakers are autonomous and independent because no auxiliary equipment is required.
6)Fire hazards are eliminated.
RELAY
A relay is an electrical switch that opens and closes under the control of another electric circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts.
Operation
When a current flows through the coil, the resulting magnetic field attracts an armature that is mechanically linked to a moving contact. The movement either makes or breaks a connection with a fixed contact. When the current to the coil is switched off, the armature is returned by a force approximately half as strong as the magnetic force to its relaxed position. Usually this is a spring, but gravity is also used commonly in industrial motor starters. Most relays are manufactured to operate quickly. In a low voltage application, this is to reduce noise. In a high voltage or high current application, this is to reduce arcing.
If the coil is energized with DC, a diode is frequently installed across the coil, to dissipate the energy from the collapsing magnetic field at deactivation, which would otherwise generate a spike of voltage and might cause damage to circuit components. Some automotive relays already include that diode inside the relay case. Alternatively a contact protection network, consisting of a capacitor and resistor in series, may absorb the surge. If the coil is designed to be energized with AC, a small copper ring can be crimped to the end of the solenoid. This “shading ring” creates a small out-of-phase current, which increases the minimum pull on the armature during the AC cycle.
By analogy with the functions of the original electromagnetic device, a solid-state relay is made with a thyristor or other solid-state switching device. To achieve electrical isolation an optocoupler can be used which is a light – emitting diode (LED) coupled with a photo transistor.
Types of relay
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Latching relay -
Reed relay -
Mercury-wetted relay -
Polarized relay -
Machine tool relay
-
Contactor relay -
Solid state contactor relay -
Buchholz relay -
Forced-guided contacts relay -
Solid-state relay -
Overload protection relay -
Pole & Throw
The following types of relays are commonly encountered:
SPST - Single Pole Single Throw. These have two terminals which can be connected or disconnected. Including two for the coil, such a relay has four terminals in total. It is ambiguous whether the pole is normally open or normally closed. The terminology “SPNO” and “SPNC” is sometimes used to resolve the ambiguity.
SPDT - Single Pole Double Throw. A common terminal connects to either of two others. Including two for the coil, such a relay has five terminals in total.
DPST – Double Pole Single Throw. These have two pairs of terminals. Equivalent to two SPST switches or relays actuated by a single coil. Including two for the coil, such a relay has six terminals in total. It is ambiguous whether the poles are normally open, normally closed, or one of each.
DPDT - Double Pole Double Throw. These have two rows of change-over terminals. Equivalent to two SPDT switches or relays actuated by a single coil. Such a relay has eight terminals, including the coil.
QPDT - Quadruple Pole Double Throw. Often referred to as Quad Pole Double Throw, or 4PDT. These have four rows of change-over terminals. Equivalent to four SPDT switches or relays actuated by a single coil, or two DPDT relays. In total, fourteen terminals including the coil.
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Protective relay -
Overcurrent rela -
Distance relay
SURGE ARRESTERS AND INSULATION CO-ORDINATION
I.Introduction:
Electrical systems by nature involve two forms of protection over current and over voltage since over current protection of electrical equipment’s are well known to all, it is not elaborated here. Over voltage protection on the other hand, remains a relatively new subject to many engineers. Both types of protection equally necessary for safe system operation.
The importance of over voltage protection for a power system can not be over emphasized. Major equipment failures, expensive repairs, personnel safety and plant down time are certain consequences of inadequate protection from voltage surges.
Surge arresters are designed to limit dangerous system over voltages. Whether lighting-or System- produced-to safe values when they occur on power systems. An arresters is a voltage limiting device. The functions are to discharge energy associated with a system over voltage condition, limit and interruption the power fellow current that follows the transient current through the arresters and return to an insulating state prepared for the next over voltage occurrence.
In performing its voltage limiting function, certain protective characteristics of the arrester must be coordinated with the prevailing insulation levels on the system being protected. Insulation is a basic factor that must be considered in the application of arresters on a system. Insulation co-ordination is only a small part of the over all subject of arrester application. Several other factors must also be considered by the engineer when selecting surge protection. The location of the arresters, the inter-connection of ground leads, the insulation level of the protected equipment and the rating of the surge arresters are important in protecting equipment from harmful over voltage.
II.Surge Arrester operation:
The basic operation of a surge arrester is single. In its noffi1al state, an arrester must act as an insulator. When a high voltage surge occurs. The arrester must cease to be an insulator and must turn into a short to-ground-in million thus of a second. The operation of the most widely used type of surge arresters the value, type of arrester is dealt with. Other types of arresters, such as expulsion arresters and line Oxide arresters (Gapless arresters) are either on the decline or too new for a general discussion at this time. The active elements of a valve type arrester are the spark gap and the valve block. these are housed in a porcelain shell for atmospheric protection and external insulation.
The gap assembly consists of a number of in-series air gaps with sufficient dielectric strength to withstand the highest power frequency on the system. During severe over voltage conditions, the gap must always, breakdown at a voltage level some what below the insulation withstand voltage level of the equipment it is protecting, other wise equipment damage and or plant down time will result. the gap therefore serves as the switch which turns on the arrester. the voltage level at which the arrester goes from the passive (insulating) to the active (conducting) state, is called the spark over voltage.
The valve block controls what happens after the arrester has been turned on. If only a gap is used, once a surge has been diverted to ground, a dead short circuit exists between line and ground and the 50 hertz-system energy tries to flow to ground causing a fuse, re-closer or breaker to operate to interrupt the system fault current.
The valve element does exactly as its name implies. It conducts when surge current is flowing and it ceases to conduct when 50 Hz line current begins to flow. the valve block is able to do this because It is made of a non-linear resistance material, silicon carbide. The valve block offers a very high resistance to 50 Hz current while displaying a low resistance to surge current. In addition, it also consumes the surge energy passes through it.
Spark over and discharge voltage are the two protective characteristics of an arrester which are used in calculating margins of protection when studying insulation co-ordination. These protective characteristics are published by arrester manufacturers.
III. Arrester Classification :
There are three classifications of surge arresters used for over voltage protection in a system.
1.Distribution Type:
The arresters are generally used in distribution system for equipment protection. Standards distribution arresters are used for protecting oil. Insulated distribution transformers, these arresters are also used as line entrance arresters, for 11KV and 22KV lines. They are the lowest in cost.
2.Intermediate Type :
These units cost approximately two or three times as much as equivalent distribution units. For this, the arrester offers lower maximum spark over and discharge voltage characteristics that afford a greater margin of protection plus the capability of discharging large surge levels. These arresters also have a pressure relief system to safely vent internal pressure if the unit falls before the porcelains shell has a chance to rupture. These arresters are used for the L.V. protection of Power transformers in sub-transmission sub-station i.e.110/33/22/11KV and 66/22/11KV sub-station.
3.Station Type:
These arresters offer the best protective characteristics and the highest thermal capability but they cost about twice as much as equivalent intermediate units. Like intermediate arresters, station arresters have a pressure-relief system to safely vent internal pressure if the unit fails before a porcelain shell has a chance to rupture. These arresters are generally used in 230KV, 110KV and 66KV systems.
4.Basic insulation level:
Basic Impulse Insulation Level (BIL) is the voltage level that equipment insulation is capable of withstanding without sustaining damage. The voltage withstand of insulation is function of time. Inorder to establish volt-time impulse insulation levels of transformers standard impulse tests standard voltage withstand tests are conducted on selected units as type test. Transformers are subjected to impulse voltage tests (at rated BIL) and a chopped wave test (15% above BIL). A steep front – of wave test (65% above BIL) is also performed on some units. A curve plotted through these three points defines the minimum insulation withstand curve for insulation co-ordination (Fig.3) The true withstand level for the transformer lies above the plotted curve.
5. Surge arrester application:
With an understanding of how an arrester performs its functions and a knowledge of equipment insulation, we can now move into the application area and consider the several factors that comprise surge arrester application as it relates to over voltage protection of transformers, The selection of surge arresters merit are carefully considered. Various factors have to be taken into account in order to arrive at a reliable and at the same time economical means of protection. The important points are:
i)Selection of rated voltage.
ii)Selection according to the standards, codes, recommendations for insulation coordination.
i)Arrester rating :
The voltage rating of an arrester is defined as the highest 50 Hz voltage at which the arrester is designed to operate and reseal effectively after a surge has passed. Because of the system grounding and connection, this, voltage is typically higher than the phase to ground voltage / on the healthy phases will increase temporarily and it depends upon the earthing factor or the system. The selection of an arrester voltage rating for station depends upon grounding system connection and system voltage rating.
Also the voltage impressed across an arrester during a surge discharge is directly proportional to the arrester voltage rating that is, a 10,000 Amps surge produces a higher discharge voltage if it is flowed through a 10KV arrester than it does flowed through a 9KV arrester generally it is desirable from the stand point of equipment protection to select the lowest voltage rating for the application.
ii)Arrester location:
Surge arresters should always be located as close as possible to the terminals of the equipment protected. In the case of transformer protection, mounting the arresters directly on the transformer is the best of insurance. An appreciable distance between the surge arrester, and the protected equipment reduces protection, afforded by the arresters and also increases the voltage impressed upon the transformer at time of surge discharge. Also because of the extra travel distance between the equipment and its arrester, surge wave could rise above the equipment damage point before the arrester comes to its rescue.
n addition, the arrester connecting leads should be kept as short as possible because of their voltage contribution to discharge the voltage. During current flow to ground through an arrester, the interconnecting leads provide a voltage contribution because of current passing through an impedance. Depending on surge magnitude, rate of rise type of conductor, a typical value of voltage contribution to discharge voltage by interconnecting leads is i.e. 1.6 KV / foot.
In practice, the protection range is given by the following simple formula.
L = U – Ua x V Where
2 X S
L = Protection range of arrester in meters
(measured along the line)
U = Impulse withstand voltage of protected equipment in KV. (BIL of equipment)
Ua = Spark over voltage of an arrester in K. V. (Peak) of the system. During earth fault conditions, the voltage
V = Velocity of wave progression with
V line = 300 meters /micro sec.
V cable = 150 meters /micro sec.
S = Steepness of incoming wave front in KV / sec.
(The protection range of an arrester increases with the difference between the impulse voltage IV’ and the spark over voltage Va. Therefore, an arrester with protective level tends to extend the protective range)
iii)Interconnection of Grounds:
It is essential that the arrester ground terminal be interconnected with the transformer tank and secondary neutral to provide reliable surge protection for the transformers.
Iv)Insulation coordination: .
Now let us consider the selection of an arrester according to standards, codes or recommendations for insulation coordination. Calculating the margin of protection is the major part of an. insulation co-ordination study. Insulation coordination is the process of comparing the impulse strength of insulation with the voltage that can occur across the arrester for the severity of surge discharge for which the protection is desired. For a transformer, this means a comparison of the volt-time insulation withstand curve with the impulse and switching surge spark over and discharge voltage curve of the arrester.
After determining the rated voltage of an arrester, the protective level has to be carefully selected. For complete protection of the equipment, the “protective level” viz. the level to which the over voltages are omitted by the arrester, must be lower than the withstand level by a factor of at least 1.2 for lightning surges and 15 for switching surges. The value thus selected must be checked against that given in I.S.S. or the technical details furnished by the arrester manufactures.
To arrive at the discharge voltage of an arrester for these calculations discharge voltage for a 10,000 Amps. surge is normally used. The following formula define these two margins of protection calculations:
CWW -FOW SO BIL -DV + IX)
MP1 = CWW x 100% MP2 = BIL x 100%
Where
CWW = Chopped -waved withstand voltage of transformer winding = 1.15 BIL
FOW SO = Front of wave spark over of surge arrester in KV (Crest)
BIL = Basic Impulse Insulation level of the transformer.
DV = Discharge voltage of the arrester at 10 KA surge.
IX = Voltage contribution of connecting leads at the rate of 1.6 KV / ft.
MP = Margin of Protection
Insulation co-ordination in an important aspect to be considered when surge protective is to be afforded to transformers with reduced BILS
vi Protection against direct strokes:
i) Protection against direct strokes can be handled by shielding the station equipment’s by the provision of either
a) Mast or rods or
b) a net work of overhead ground wires in such a way that equipment’s and switches of all lie in the protected zone.
ii) The protected zone for a rod mast is generally assumed as a cone with a base radius equal to the height of the rod or mast above ground.
iii) For small sub-stations it may be sufficient to run one or GI wires across the station from adjacent line towers. Extra wires may be run from the tower to the structure and over the station.
iv) The grounds of the station shield should be solidly tied to the station ground bus to prevent difference of surge potential between the shield and other g-rounded parts of the Station.
SAFETY IN SUB-STATION
Prevention of damages to equipment’ s and men working on then due to any accidents is an essential aspect in any establishment. Prevention of accident which is an unforeseen one is more essential aspect of any establishment / organisation.
As accidents occur mainly due to unsafe execution, actions and circumstances, these accidents can be avoided by adopting safety precautions, implementing safety procedures and following safety rules.
General safety methods:
I. While execution of any work, that part of equipment or line is to be isolated from the supply.
2. Using discharge rods, charging, current if any is to be discharged.
3. Using Earth rods, all phases/conducting path are to be property earthed by securing good Earthing.
4. When even opening an AB switch or removing of fuse, it is also advisable and preferable to wear rubber gloves.
5. Use of belt rope is another safety method to be adopted to work on elevated places.
Safety methods to be adopted in Sub-Stations :
In any work is to be attended to any line, first and fore most item of work is to get proper approval from the competent controlling authority for execution of the work specifying the date, time, duration, place of work, affected parties etc. .
For Grid feeders and Stations, the authorized officer for issue of approval is S.E. (L.D. Centre), Madras, For 110 KV, 66 KV, radial feeders Superintending Engineer / Distribution is the approving authority. Similarly for 33 KV Divisional Engineer incharge of distribution is the approving authority.
Above details with the list of authorised officers is enclosed herewith (enclosure I)
Without obtaining proper approval from the competent authority, no L.C. should be issued nor availed by anybody. If the above procedure is not followed, it is nothing but a suicidal. Further it also amounts to murder of others.
So, after getting proper approval, line clear is to be issued to the requested party. But the issue and receiver should be aware/have full knowledge about the SS equipment’s, control room panel details etc.,
The line clear issuing person should clearly record the following:
a) Which breaker have been tripped
b) Which A.B. switches were opened
c) Where Earthing was done
d) What is the Safer place / Line to carry on the execution of work
Safety arrangements in control room:
1) Key Board should be in open condition so that the keys could be taken out quickly during any urgency.
Line clear keyboard should be in locked up condition to prevent other persons from using the keys inside, before the cancellation of the Line clear permit.
The keys should be placed in the key board in an orderly manner according to their numbers. Otherwise, the required lock could not be opened in time and the possibility of opening a wrong lock may happen.
2) Rubber mat should be provided on the floor in front of the panel board.
3) The following details should be clearly displayed in the control room.
Approved operating instructions for all equipment’s.
Break down instructions.
Operating instructions including for the emergency operations to be carried out in the event of operation of buchholz relay. Differential relay, Group control trip, total supply failure, grid failure. The operator should be fully conversant with the above instructions and the must be able to act quickly and effectively.
4) The Board containing D.C. cable layout. A cable layout panel wiring diagram and Earthing layout should be displayed in the control room. This is necessary to attend the faults immediately after their occurrence.
5) D.C. Earth leakage test system should be available.
6) There should not be any defective power plugs, switches and bulb holders in the control room wiring.
7) One artificial respirator should be available in ready condition.
8) Stools made of insulating material should be used for operating high tension communication equipment’s (Telephones).
9) Adequate number of rubber gloves, belt ropes, discharge rods, and earth rods in good condition should be available in the control room.
Battery room:
1. Battery room should be in locked up condition.
“Naked flame is prohibited inside of the battery room” and “Smoking prohibited” warnings should be kept written on the battery room door.
2. One exhaust fan should be functioning.
3. Accurate D.C. cell testing volt meters, hydro meters and thermometers should be available in the battery room.
4. Pilot cell voltage, specific gravity and temperature should be taken every week.
5. The specific gravity should not be maintained below 1195 at 15.6°C and below 1183 at 32. 20°C. The battery should not be allowed to discharge below 1160.
6. Cell voltage should be maintained between 1.95 V to 2.05 V. The battery should not be allowed to discharge below 1.85 V.
7. Battery should be allowed neither to over charge not to undercharge. It should not also be kept idle.
8. Electrolyte level must be checked in every shift. It must be ensured that the level is 10mm above the top of the plates.
9. Weak cells should be rectified then and there.
10. While taking specific gravity readings, care must be taken not to allow the acid to come in contact with the eyes.
Safety adopted for transformers:
1. Transformers are to be maintained periodically as per schedule. Switches on HV side and LV side are to be isolated after reducing the Load by tripping the breakers.
2. Kiosks and OCB : All the Live parts of the kiosk should have H. T. insulation tape. To be protected by wiremesh. It should be vermin proof. Keys are to be kept with interlock. When ever to open the door of the kiosk, kiosk should be tripped link should be opened by the interlock key. The opening of the links are to be verified physically. After doing all the above precautions, the tank should be lowered down. Proper care is to be taken and it should be kept in mind that supply is available at the roofing.
Oil leak should be arrested. Back feeding is avoided.
Cotton waste should not be used for cleaning purpose.
3. AB switches:
Handle of the AB switch is to be earthed properly. Blades should be kept at opening position. It should not be closed automatically, proper maintenance is to be done for this. AB switch blades are to be opened fully. AB switches are to be kept locked on both conditions. AB switches are to be opened only after tripping the breakers.
4. Lightning arresters :
Lightning arresters are used to bypass the sudden lightning surges and thereby to protect the equipment’s.Only after proper discharging is done on lightning arresters, it should be attempted to attend to maintenance.Fencing is to be provided around lightning arresters. Door arrangements with lock is to be provided. Separate earth connections are to be provided for lightning arresters.
5. Current transformers:
Current transformer secondary side is to be short circuited during maintenance and testing. Before doing any testing, the current transformers are to be discharged.
6. Potential transformers:
Potential transformers primary side is to be Earthed during maintenance and testing. Secondary side is to be earthed at only one place. Whenever giving connection, or removing meters on the secondary side of die potential transformer, the fuses are to be removed and renewed.
7. Capacitors and H. T. Coupling capacitor:
Capacitors should be provided inside fencing. Before attempting to do any work, proper discharging is to be done. They only it should be attempted for maintenance work. Proper Earthing should be provided during the execution of the work. After completion of the work, Earthing is to be removed.
8. Earth pits:
Sub-station earth connections should be properly maintained so that the earth resistance is minimum. Water should be poured in the earth pits daily. Earth connections, must be capable of protecting the persons working in the electrical equipment’s and protect in the equipment’s during heavy fault current. Earth resistance should not exceed the following limits.
Grid stations: I Ohm Other sub-stations ..2 Ohm.
Distribution transformers ..5 Ohm.
They must be a clearance of 5 feet, between the sub-station fence and the electrical equipment’s / live points. The fence should be earthed at every 200 feet, separately. Generally the fence Earthing should not be linked with the sub-station Earthing. But if the clearance is less than 5 ft. feet fence Earthing must be linked with the sub-stations Earthing. The iron gates in the sub-station fence should also be earthed separately.
9. Fire fighting equipments:
These equipment’s are to be kept on good and working condition. Proper schedule of maintenance is to be done for keeping them in good conditions. These equipment’s should be kept at an easily accessible place so as to use them immediately under emergency. Dry sand heaps are to be available wherever necessary. Empty buckets are to be provided.
10. S.S. Yard:
1. S.S. yard should be provided with fencing.
2. Unauthorised persons should not enter into the yard
3. Cable ducks are to be provided with slabs.
4. Best illumination is to be provided for the yard.
5. A warning board with a display that “Umbrella” stick Dogs should not be brought inside the yard” is to be provided at the entrance of the yard.
6. A separate room is to- be provided for keeping the empty drums. At the entrance of the room “No smoking” Board is to be provided.
General
1. The territory of the work spot which was declared safety to work is to be clearly identified by tying a rope. Inside this boundary is to be further identified by hanging a green flag. Outside this boundary where it is unsafe to work is to be identified by a red flag.
2. Wherever necessary caution boards like “Men on working” “Don’t Switch on“ Safe for work” etc., are to be provided.
3. If any unauthorized, unskilled staff happen to go near the equipment’s he can do so with the assistance and under the vigil of an experienced, authorised staff.
4. Conversation is strictly prohibited wile execution of any work. It should be totally avoided especially when work is being carried out on any bus bars.
5. Placing the materials, tools and plants and men are to be at a safety clearance from the Live. parts.
6. T & Ps like spanners etc. are to be lifted and brought down only by means of ropes and not by throwing and catching.
7. Study and safe ladder with steps at convenient intervals is to be used. To avoid slippage of the ladder, necessary precaution is to be taken at the bottom of the ladder by providing empty gunnies.
8. Lifting of any ladder or rods (Earth) are to be done only horizontally. Vertical
lifting may cause damages by interrupting with the safe clearances.
9 The bus and line links art’; to be kept opened while doing work on OCB and
About the Author
Gas Rc Boat Engines
Gas Rc Boat Engines
my echo gt-2000 wont start?
i was given a rc boat than had been made out of an echo gt-2000 problem is it wont start. gas tank has plenty of fuel and its getting to the engine. so fuel isnt the problem. i put in a brand new spark plug and tested that. when plugged in and grounded it doesnt produce a spark. put it in another echo and it did, so its not the spark plug thats bad but it still doesnt spark. please help
if you don’t get a spark and the plug is ok then you have coil /magnet(rare) problems.Check coil resistance (then replace it)(it may be cheaper to just get another motor).
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Exceed Rc Drift
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Fundamentals of Parametric Testing of Phase Change Memory
A PCM cell is a tiny chunk of a chalcogenide alloy that can be switched rapidly from an ordered crystalline phase (with low resistance) to a disordered, amorphous phase (with much higher resistance) through the focused application of heat in the form of an electrical pulse. These same materials are also widely used in the active layers of re-writable optical media such as CDs and DVDs. The switch from the crystalline to the amorphous phase and back is triggered by melting and quick cooling (or a slightly slower process known as re-crystallization). According to Keithley Instruments, www.keithley.com , one of the most promising PCM materials is GST (germanium, antimony, and tellurium), which has a melting temperature in the range of 500º–600ºC.
Amorphous state vs. the crystalline state. The differing levels of resistivity of the crystalline and amorphous phases of these alloys allow them to store binary data. The high resistance amorphous state is used to represent a binary 0; the low resistance crystalline state represents a 1. The newest PCM designs and materials can achieve multiple distinct levels [1], for example, 16 crystalline states, not just two, and each with different electrical properties. This allows a single cell to represent multiple bits, and to increase memory density substantially.
In the amorphous phase, the GST material has short-range atomic order and low free electron density, which results in higher resistivity. This is sometimes referred to as the RESET phase, because it is usually formed after a RESET operation, in which the temperature of the PCM device under test (DUT) is raised slightly above the melting point, then the GST is suddenly quenched to cool it. The rate of cooling is critical for the formation of the amorphous layer. The typical resistance of the amorphous layer can exceed one mega-ohm.
In the crystalline phase, the GST material has long-range atomic order and high free electronic density, which results in lower resistivity. This is also known as the SET phase because it is formed after a SET operation, in which the temperature of the material is raised above the re-crystallization temperature but below the melting point, then cooled slightly slower to allow crystalline grains to form throughout the layer. The typical resistance of the crystalline phase ranges from 1 to 10 kilo-ohms. The crystalline phase is a low energy state; therefore, when heat is applied to material in the amorphous phase and the temperature approaches the crystallization temperature, it tends to change spontaneously to the crystalline phase.
The structure of a typical GST PCM device has a resistor attached to the underside of the GST layer that acts as a heating element. Electrical current though it causes localized heating/melting that affects only a small area around the tip of the resistor. Erase/RESET pulses set high resistance or logical 0 and form an amorphous layer area on the device. Erase/RESET pulses are higher, narrower, and steeper than Write/SET pulses. A SET pulse, which sets a logical 1, re-crystallizes the amorphous layer back to the crystalline state.
Pulse requirements for PCM device characterization. The voltage and current values of the RESET and SET pulses used should be carefully selected to produce melting and re-crystallization. RESET pulses should raise the temperature just above the melting point and then allow the material to cool rapidly to the amorphous phase. SET pulses should raise the temperature just above the re-crystallization temperature but below the melting point, and allow a longer time to cool it; therefore, the pulse width and fall time for a SET pulse should be longer than for a RESET pulse.
In functional testing, pulse widths of one microsecond or shorter are usually sufficient. A pulse of this duration will produce enough energy either to melt PCM material or to re-crystallize it. Pulse voltages need to be as high as 6V, and it’s desirable for them to be higher, to reach melting temperatures. Current values range from 0.3–3mA.
Fall time for a RESET pulse is a critical parameter [2]. The state of the PCM technology determines the required minimum for a fall time. Currently, it is a common requirement to have 30–50 nanoseconds. Newer materials will push that requirement to shorter fall times. If the pulse fall time is longer than that required time, the material may not effectively quench into an amorphous phase.
Critical parameters for PCM device characterization and materials research. The ability to develop new PCM materials and refine device designs depends largely on manufacturers’ abilities to characterize several parameters:
- Re-crystallization rate – Current re-crystallization rates are now as short as several tens of nanoseconds, but they may soon drop to as little as a few nanoseconds. That will make reducing the time needed to make a measurement increasingly crucial.
- Data retention – As discussed previously, the SET phase is a lower energy state, and PCM materials tend to re-crystallize spontaneously. The rate of crystallization is temperature dependent. Therefore, data retention can be defined as a maximum temperature at which data, the RESET state, will remain unchanged and stable for a specified time period (typically 10 years).
- Cycling endurance – This is a measurement of how many times a memory cell can be successfully programmed to the 0 and 1 states. The newer multi-state memory cells with additional distinct states mentioned previously allow packing more memory into a single cell, which modifies cycling endurance test procedures.
- Drift – This is simply a measure of the drift of the cell’s resistance over time, typically performed at various temperatures [3].
- Read Disturb – This is an evaluation of how the “read” procedure impacts the stored state. The measurement pulse must be less than 0.5V. Higher voltages will lead to Read Disturb problems.
- Resistance-current (RI) curves – The RI curve is one of the most common parameters collected during PCM characterization. A pulse sequence is sent through a DUT. The first one, a RESET pulse, sets the resistance of the DUT to the high value. It is followed by a DC-read or MEASURE pulse that’s usually 0.5V or lower in order to avoid affecting the state of the DUT. This is followed by a SET pulse and another MEASURE pulse. The entire sequence is repeated multiple times, with the amplitude of the SET pulse slowly increased to the value of the RESET pulse. RESET values slightly exceed 1MΩ; SET resistance values range from one mega-ohm to several kilo-ohms, depending on the value of the SET current.
- I-V (current-voltage) curves – To generate these curves, the starting point is a DUT that was previously RESET to its highly resistive state. Then voltage applied to the DUT is swept from low to high values. The dynamic switch from a high- to low-resistive state in the presence of a load resistor produces a characteristic RI curve with a snapback, an area of negative resistance.Snapback itself is not a feature of PCMs or of PCM testing, but rather a side effect of the R-load technique that has long been used to obtain both RI and I-V curves.
In the standard R-Load measurement technique a resistor is connected in series with the DUT, allowing current to be measured across the DUT by measuring the voltage across the load resistor. Active, high impedance probes and an oscilloscope are used to record the voltage across the load resistor. Current across the DUT will be equal to the applied voltage (VAPPLIED) minus the voltage across the device (VDEV), divided by the load resistance. The values of the load resistor usually range from one to three kilo-ohms. This technique involves a tradeoff: if the load resistance is too high, RC effects and the voltage division between the R-Load and the DUT limits this technique’s performance; however, if the resistor value is too small, it impacts the current resolution.
A New Measurement Technique. Recently, a new current-limiting technique has been developed that eliminates the need for the load resistor. Tight control over the level of current sourced allows for more accurate characterization of low currents in the RI curve. This new pulse mode technique, which allows taking both I-V and RI curves in a single sweep, employs a high-speed pulse source and measure instrument: the Keithley dual-channel Model 4225-PMU Ultra-Fast I-V Module installed in a Model 4200-SCS Semiconductor Characterization System. The new module can source voltage pulses and simultaneously measure both voltage and current responses with high accuracy, with rise and fall times as short as 20ns.
The elimination of the load resistor also eliminates the snapback side effect. The Model 4225-PMU, and the Model 4225-RPM Remote Amplifier/Switches that extend its sensitivity, are tightly integrate with the Model 4200-SCS parametric tester, which not only provides the other measurement functions necessary to characterize a PCM device but also offers the ability to automate the entire testing process.
Conclusion. As industry looks for more reliable memory devices, the ability to characterize these new devices quickly and accurately during development becomes increasingly important. New tools and techniques now being developed will be critical to this pursuit.
About the Author
Alex Pronin is a lead applications engineer with <a href=”http://www.keithley.com/”>Keithley Instruments</a> in Cleveland, Ohio. He holds an M.S. in Physics from the Moscow Institute of Physics and Technology and a Ph.D. in Material Science from Dartmouth.
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remote control rc radio control SUPER BRUSHLESS 1/8Th Exceed RC Madbash Electric Brushless Racing Edition RTR Ready to Run Rally Car Star -COLOR VARIES SENT AT RANDOM – ALSO INCLUDES MKS Drift Pro GD-4 RC Car Drifting Gyro (THIS WILL PROVIDE INCREDIBLE HANDLING ABILITY EVEN FOR A BEGINNER) $799.99 This massive 1/8 MadBash EP Brushless Rally comes with 540L Brushless Motor for speed of swiftness, twin 7.4v 3300mAh 25C Lipo Battery pack, polished aluminum chassis to provide clean look as well as sturdiness, and adjustable shocks to have perfect landing. FX-2 Sport Radio& 540L Brushless Massive pre-glued 4.75″ Tires Mounted on… |
Axial Wheels
Axial Wheels
Re-Design Of High Temperature Axial Fans
NISCO Fan Co. just increased the temperature rating of the high temperature construction on its axial fans. There are a few steps of fan heat construction available: 200 F, 725 F, 800 F. High temperature inline fans are ideal for industrial oven and dryer exhaust systems where pressure requirements are minimal and compact light-weight designs are advantageous.
200 F High Temperature Duct Fans come with special heat bearings and a belt drive with increased safety factor.
650 F Tubeaxial Fan design involves special belt tunnel cooling system that induces a flow of cooler, ambient air through the belt well and inner tube, cooling the fan’s internal components. Depending on temperature requirements, modifications include high-temperature alloy fan wheel, special drive components, and modifications to provide internal ambient air cooling.
Fans with ambient air cooling systems handling hot airstreams must have sufficient airflow and be kept in operation until airstream temperatures cool below 120 F to prevent damage to the fan unit. The Tubeaxial fan ambient air cooling system is only effective while fan is operating.
800 F Vaneaxial Fans are designed to operate continuously at temperatures to 800 deg. F, and include an auxiliary cooling fan that forces air through the bearing compartment and exits out through the insulated belt opening taking away excessive heat from the shaft and bearings. A high temperature shaft seal is also standard on this design.
Fans handling hot airstreams must have sufficient airflow and be kept in operation until airstream temperatures cool below 120 F to prevent damage to the fan unit. The Tubeaxial fan ambient air cooling system is only effective while fan is operating.
The NISCO complete high temperature fans line now include:
- Operating up to 2200 F, centrifugal, axial and plug fan types;
- Pre-engineered and custom made fans for all types of applications with vaiety of impeller types and accessories;
- NISCO engineers provide a professional advice and recommend a right fan for every application & oven / plenum design;
- The fan offering provides competitive replacement fans to Garden City, Lau, IGE, Alloy Fabricating fan models; repairs, re-build & balancing;
- Unique high temperature water-cooled motors for operation up to 2300 F;
in the two major types of high temperature fans – centrifugal and axial:
Centrifugal Wheels:
* Multiblade forward curve wheel. This type of wheel is usually specified where there is a necessity for large volumes of flow against low to medium static pressure requirements. The forward curve blade is that it delivers the same volume of air as either the backward or radial blade wheel, at a lower fan speed, which is important due to wheel stresses at elevated temperatures. This fan is the most common type used in all types of heat treatment operations except where a buildup of material on the blades could occur, as wheel unbalance would result.
* Radial Blade, paddle wheel type fans. This type of wheel is usually specified where there is a necessity for medium volumes of flow against medium to large static pressures. The paddle wheel is considered a self cleaning type of wheel. It could be used where there are various materials or dust in the air stream. Due to its structurally strong design, it is used in many heat treatment applications at very high temperatures where maximum fan longevity is desired.
Axial Blade Wheels:
* The axial blade wheel is usually specified where there is a need for very large volumes of flows against low static pressure. Axial wheel like the multi-blade forward curve type wheel could cause an axial fan to deliver different air volumes at the same static pressure, if the total pressure requirement of the fan system was underestimated. This type of fan is ideally suited where a large volume of flow is required with a minimum of duct work and is used extensively for small and large furnaces, such as aluminum annealing.
For additional information please refer to http://www.nisco.net/nyb.html.
Oleg Tchechel
Industrial air systems designer
NISCO
http://www.nisco.net/fanblower.html
http://www.nisco.net/aircurtain.html
About the Author
Oleg Tchechel
Developer of Industrial Ventilation Equipment
NISCO Fan Co.
http://www.nisco.net/custserv.html
http://www.nisco.net/inquiry.html
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Power Boss 020309 3,000 PSI 2.5 GPM 187cc Honda GC190 Gas Powered Pressure Washer $479.97 Powered by a Honda OHC engine, this pressure washer is great for cleaning siding, driveways, and second stories. The maintenance-free axial cam pump with Easy Start┢ technology produces 3000 psi @ 2.5 gpm providing enough cleaning power for any project…. |
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Karcher K 2.28 1,550 PSI 1.3 GPM Electric Pressure Washer With 20-Foot Hose $109.99 Karcher’s K 2.28 is an affordable pressure washer that delivers German engineering at an entry-level price. This lightweight, compact electric pressure washer delivers up to 30 times as much pressure as your garden hose, making it the perfect tool for keeping your sidewalk, patio, driveway and deck clean of dirt and mud. The K 2.28 packs plenty of power for most cleaning projects around the home, … |
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EDIC Aviator Air Mover Axial Fan with Wheels 3009AF-W Superior performance, design and engineering makes our new axial fan the most efficient in the industry, providing more CFM with a lower amp draw. Use our large-sized blower to tackle ever the toughest water damage restoration and carpet drying jobs in a hurry. With an amazing velocity of 3000 CFM at a super-low 2.3 amps, the Aviator literally blows away the competition! The bottom line is a much … |
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Bailey Work Hardening Components Axial Resistance Shoulder Wheel – Model 925633 $1,164.90 Allow therapist to progressively challenge individuals to build strength and endurance for work activities. On-the-job work tasks simulated include lifting boxes, hand and electrical assembly and shoveling. Individual components are described below. Weight Sled: (5455) Simulates everyday work motions. Handle adjusts from 32″-44″H. Foam-covered grips and four removable weight holders. 18″W x 36″L. … |
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Syma S109G Apache AH-64 3.5-Channels Mini Indoor Helicopter $21.99 The Syma S109G is a palm size 3-Channels Helicopter, it has a youngest brother in the Syma Apache line. The S109G has a Co-Axial structure which is specially made for first time flyers. The S109G is built with thick plastic body which always survives in crashes. The Syma S109G is equipped with a 4-in-1 receiver (Gyro, ESC, Mixer, Receiver), allows the helicopter to move in all directions. This hob… |
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3.5-Ch Metal Outdoor RC Helicopter S032 $36.98 Brand new s032 3.5 channel rc helicopter with gyro ready to fly kit is now available to you for best price you want…. |
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Syma S033G 3.5 Channel 700mm Large RC Helicopter Ready to Fly. Colors May Vary in Yellow or Red. $59.95 Syma S033G Larger RC Helicopter Specifications: Product size:67 x 30 x 13 cm Package size:86 x 50 x 15 cm Helicopter Battery: 7.4V 1100Mah Li-poly(include) Transmitter Batteries:4 x AA Batteries(not include) Flying time:8-12mins Remote distance:approx 60m Remote control frequency:27mhz/40mhz Syma S033G Radio Control Helicopter Package Include: 1 x 3ch S033 helicopter 1 x Remote Radio Controller 1 … |
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Logitech Xbox 360 DriveFX Axial Feedback Wheel $99.99 Buckle your seatbelt and hold on! Featuring Logitech Axial Feedback technology, the DriveFX wheel takes ordinary vibration effects from your Xbox 360 racing games and turns them into an exciting new driving experience. You’ll feel all the curbs, bumps and crashes with greater realism.Platform: XboxPackaging: Box… |
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Axial XR10, Plastic Steering Knuckles Set, AX80061 $11.00 XR10 STEERING KNUCKLES SET… |
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Fan Handbook: Selection, Application, and Design $29.87 Here is the first comprehensive guide to all aspects of modern fan technology. The book takes you through the design, selection, maintenance, and repair of fans used in a wide range of applications and industries, including airfoils…centrifugal fans…mixed-flow fans…roof ventilators…cross-flow blowers…regenerative blowers… and more. You’ll find information on fan codes, standards, and s… |
Axial Flow Fans
Axial Flow Fans
Centrifugal Blowewr vs Axial Fan
The main types of Axial Flow Fans include:
High-Temperature Axial Fans – High-volume fans designed to operate against low flow resistance in industrial convection furnaces. These are found in either single-direction or bi-directional designs. Extremely rugged, they are most often used in high-temperature furnace (up to 1800 degF) applications.
Tube Axial Fans – Cataloged high-volume low-pressure fan line with a wide range of available sizes. Suitable for temperatures up to 250 degF.
Vaneaxial Fans – Axial flow fans with higher pressure capability due to the presence of static vanes.
Variable Pitch Axial fans – Axial fans with manually adjustable blade angles. This allows operation over a much wider range of volume/pressure relationships. The blades are adjusted periodically to optimize efficiency by matching the blade pitch to the varying conditions for the application. (Often used in mining applications).
Variable Pitch on-the-fly Axial Fans – These are similar to “Variable Pitch Axial Fans” except these include an internal mechanism that allows the blade pitch to be adjusted while the fan rotor is in motion. These versatile fans offer high-efficiency operation at many different points of operation.
Variable Speed Fans – All of the fans described above can be used in conjunction with a variable speed driver. This might be an adjustable frequency AC controller, a DC motor and drive, a steam turbine driver, etc. Flow control by means of variable speed is typically smoother and more efficient than by means of damper control. Significant power savings (with reduced cost of operation) are possible if variable speed fan drives are used for applications that require reduced flow operation for a significant portion of the system operating life.
Airfoil Centrifugal Fans are used for a wide range of applications in many industries, hollow-bladed airfoil fans are designed, engineered and tested for use in airstreams where high efficiency and quiet operation are required. They are used extensively for continuous service at ambient and elevated temperatures in forced and induced draft applications in the metals, chemical, power generation, paper, rock products, glass, resource recovery, incineration and other industries throughout the world.
Backward Curved Fans – Efficiencies nearly as high as the airfoil design. However, single-thickness metal blades prevent the possibility of dust particle buildup inside the blade. These fans can be built with long-lasting erosion-resistant liners. The robust design allows high tip-speed operation, and therefore this fan is often used in high-pressure applications. This design frequently offers the best compromise for long life and high efficiency.
Backward Inclined Fans – Simple flat blades, but backwardly inclined to match the velocity pattern of the air passing through the fan wheel, which results in high-efficiency operation. These fans are typically used in high-volume, relatively low-pressure, clean air applications.
Radial Blade Blowers – Flat blades oriented in a radial pattern. These rugged fans offer high pressure capability with average efficiency. They are often fitted with erosion-resistant liners to extend the rotor life. The housing design is compact to minimize the floor space requirement.
Forward-Curved Radial Tip Fans – This rugged design is used in high-volume flow rate applications when the pressure requirement is rather high and erosion resistance is necessary. It offers medium range efficiencies. A common application is the dirty side of a baghouse or precipitator. The design is more compact than airfoil, backward curved or backward inclined fans.
Paddle-Wheel Blowers – This is an open impeller design without shrouds. Although the efficiency is not high, this fan is well suited for applications with extremely high dust loading. It can even be offered with field-replaceable blade liners from ceramic tiles or tungsten-carbide. This fan may also be used in high-temperature applications.
Forward-Curve Fans – This “squirrel cage” impeller generates the highest volume flow rate (for a given tip speed) of all the centrifugal fans. Therefore, it is often the smallest physical package available. It is commonly used in high-temperature furnaces.
Industrial Exhausters – Relatively inexpensive, medium-duty, steeply inclined flat-bladed fan for exhausting gases, conveying chips, etc.
Pre-engineered Fans – are series of fans of varying blade shapes that are usually available in only standard sizes. Because they are pre-engineered these fans may be available with relatively short delivery times. Often, pre-engineered rotors with various blade shapes may be installed into a common housing. These are often available in a wide range of volume and pressure requirements to meet the needs of many applications.
Pressure Blowers – High-pressure, low-volume blowers used in combustion air applications in furnaces or to provide “blow-off” air for clearing and/or drying applications.
Surgeless Blowers – High-pressure, low-volume blowers with a reduced tendency for “surging” even at severely reduced flowrates. This allows extreme turndown (low-flow) without significant pulsation.
For additional information please refer to http://tenderall.com/index.html.
Oleg Chetchel
Industrial Process Equipment Designer
Tenderall Fan Co.
http://tenderall.com/ventilator/index.html
http://tenderall.com/blower/index.html
About the Author
Oleg Chetchel
Ventilation Equipment Designer
Tenderall Fan Co.
http://tenderall.com
Silvan Storm orchard sprayer
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110V / 115V / 120V AC Cooling Fan. 120mm x 38mm HS + Power Plug Cord Overview The high speed 120 by 120 by 38 millimeter 115V AC cooling fan has terminal connectors and can run on 100 to 125 voltages. The fan contains long life dual ball bearings rated at 67,000 hours and can be mounted in any direction. Its housing is constructed of die-cast aluminum and blades molded of thermoplastic. Includes a 4 feet power plug cord that easily attaches to the fan and can be pl… |
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6-Inch 110VAC 250 CFM In-Line Duct Fan $24.99 Imagine being able to walk into a room, press a button and have the airflow only to that room immediately boosted by up to 80%, quietly. Increase ventilation to selected areas when guests are over, equalize temperatures in rooms that are too hot or too co… |
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MaxxAir HVHF 08COMBO Heavy Duty 8-Inch Cylinder Fan with 20-foot Vinyl Hose, Yellow $171.40 … |
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Tjernlund Duct Booster Fan – 300 CFM, 120 Volt $57.58 Fans boost air flow in hard to heat or cool rooms. Install easily in both metal and flex round duct. 8in. fan has 120 Volt, 56 Watt motor, moves 300 CFM through 25ft. of straight duct. U.S.A. Auto and Manual: Yes, CFM: 300, Works With: Heating ducts, Motor: 56 Watt motor, Mount Type: Hardwired or wire to an off and on switch (special order), Dimensions L x W x H (in.): 8in. Diameter and 9in. Len… |
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Thermocool Axial Cooling Fan 110V 57CFM 4.72 X 4.72 $8.60 __Thermocool Axial Fans provide enhanced cooling for a variety of electronic devices. Leading air flow technology is designed into every Thermocool product resulting in reduced turbulence, low noise levels and a more energy efficient product. Thermocool fans are ideal for use in computer systems, portable CD and DVD players, stereo components, overhead projectors, laptop computers, and many other … |
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AVC 40mm x 28mm 1U Axial Fan $6.00 This is New AVC 40mm x 28mm 1U Axial Fan pulled out of from our 1U chassis. It is a high-end 40mm DC Fan and UL , CSA, Intel approved with 3-pin connector…. |
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Lian-Li Aluminum PCI Cooling Kit Model BS-03X Black $24.99 Lian-Li Aluminum PCI Cooling Kit Model BS-03X Black Specialty Cooling fan, housing and grill made to install in newer Lian Li Cases. Attaches inside to back of case where perforated holes vent to outside. See pictures for a closer look Large 12cm axial fan sucks hot air up from expansion cards and exhausts out the back of the case. This is same fan assembly found in Plus II and other newer Lia… |
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Thermocool Axial Cooling Fan 110V 19CFM 3.15 X 3.15 $8.00 Thermocool Axial Fans provide enhanced cooling for a variety of electronic devices. Leading air flow technology is designed into every Thermocool product resulting in reduced turbulence, low noise levels and a more energy efficient product. Thermocool fans are ideal for use in computer systems, portable CD and DVD players, stereo components, overhead projectors, laptop computers, and many other el… |
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Fan Handbook: Selection, Application, and Design $29.87 Here is the first comprehensive guide to all aspects of modern fan technology. The book takes you through the design, selection, maintenance, and repair of fans used in a wide range of applications and industries, including airfoils…centrifugal fans…mixed-flow fans…roof ventilators…cross-flow blowers…regenerative blowers… and more. You’ll find information on fan codes, standards, and s… |
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Turboblowers: Theory, Design, and Application of Centrifugal and Axial Flow Compressors and Fans … |
