wound rotor motor

However, blocked rotor current test is conducted on wound rotor motors.

Transistorized inverters with variable-frequency drive can now be used for speed control, and wound rotor motors are becoming less common.

The blocked rotor torque test is not performed on a wound rotor motors because the starting torque can be varied as desired.

This reactor or filter reduces the voltage stack up that can occur on older high impedance motors such as wound rotor motors.

In wound rotor motors, rotor circuit connection through slip rings to external resistances allows change of speed-torque characteristics for acceleration control and speed control purposes.

Liquid rheostats were sometimes used in large (thousands of kilowatts/horsepower) wound rotor motor drives, to control the rotor circuit resistance and so the speed of the motor.

Applications such as electric overhead cranes used DC drives or wound rotor motors (WRIM) with slip rings for rotor circuit connection to variable external resistance allowing considerable range of speed control.

Compared to squirrel cage rotors and without considering brushless wound-rotor doubly fed technology, wound rotor motors are expensive and require maintenance of the slip rings and brushes, but they were the standard form for variable speed control before the advent of compact power electronic devices.