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The Start switch will then open and the motor will be at operational speed; Since 1920, the autotransformer starter has been the most popular device for reducing the starting current inrush for induction motors; it provides maximum starting torque with minimum line current. Table 1 - Starting Torque /Current with 3 Reduced Voltage taps
A motor soft starter is a device used with AC electrical motors to temporarily reduce the load and torque in the powertrain and electric current surge of the motor during start-up. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power cables and electrical distribution network ...
It is also known as short-circuit test (because it is the mechanical analogy of a transformer short-circuit test), [1] locked rotor test or stalled torque test. [2] From this test, short-circuit current at normal voltage , power factor on short circuit, total leakage reactance , and starting torque of the motor can be found.
For example, an unloaded motor of = 5,700 rpm/V supplied with 11.1 V will run at a nominal speed of 63,270 rpm (= 5,700 rpm/V × 11.1 V). The motor may not reach this theoretical speed because there are non-linear mechanical losses.
By adjusting the shape of the bars in the rotor, the speed-torque characteristics of the motor can be changed, to minimize starting current or to maximize low-speed torque, for example. Squirrel-cage induction motors are very prevalent in industry, in sizes from below 1 kilowatt (1.3 hp) up to tens of megawatts (tens-of-thousand horsepower).
The speed and torque characteristics of a wound-rotor motor can be adjusted by changing the external resistance, unlike a squirrel cage motor which has a fixed characteristic. This is useful for speed control of the motor. [1] A wound-rotor motor can be used in several forms of adjustable-speed drive. Common applications include hoists and ...
An automobile starter motor (larger cylinder). The smaller object on top is a starter solenoid which controls power to the starter motor and engages the Bendix drive.. A starter (also self-starter, cranking motor, or starter motor) is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power.
If the brushes are shifted counter-clockwise from the main magnetic axis, the motor will rotate in a counter-clockwise direction. Torque and speed control. The starting torque of a repulsion motor is determined by the angle of brush shift from the main magnetic axis. The maximum torque is obtained from a brush shift of 45 degrees.