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Self-starting polyphase induction motors produce torque even at standstill. Available squirrel-cage induction motor starting methods include direct-on-line starting, reduced-voltage reactor or auto-transformer starting, star-delta starting or, increasingly, new solid-state soft assemblies and, of course, variable frequency drives (VFDs). [39]
Korndorfer starter with motor (M), autotransformer (AT) and three switches (1, 2, 3) In electrical engineering, the Korndorfer starter is a technique used for reduced voltage soft starting of induction motors. The circuit uses a three-phase autotransformer and three three-phase switches. This motor starting method has been updated and improved ...
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 ...
A blocked rotor test is conducted on an induction motor.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]
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 ...
In vector control, an AC induction or synchronous motor is controlled under all operating conditions like a separately excited DC motor. [21] That is, the AC motor behaves like a DC motor in which the field flux linkage and armature flux linkage created by the respective field and armature (or torque component) currents are orthogonally aligned such that, when torque is controlled, the field ...
An induction motor is an asynchronous AC motor where power is transferred to the rotor by electromagnetic induction, much like transformer action. An induction motor resembles a rotating transformer, because the stator (stationary part) is essentially the primary side of the transformer and the rotor (rotating part) is the secondary side.
The direct torque method performs very well even without speed sensors. However, the flux estimation is usually based on the integration of the motor phase voltages. Due to the inevitable errors in the voltage measurement and stator resistance estimate the integrals tend to become erroneous at low speed. Thus it is not possible to control the ...