The Three-Phase Rheostat module consists of three rheostats mounted on a common shaft directly controlled by a single knob on the module faceplate. The rheostats are electrically interconnected in a four-wire wye configuration and each leg is protected from over-current conditions by a thermal-magnetic circuit breaker.

The module is mainly used for speed control of a Three-Phase Wound-Rotor Induction Motor., Model 8231. This module can also be used for other applications where a variable power resistor is needed.