MOTOR CONTROL APPARATUS WITH TRUE RMS NON SINUSOIDAL NEGATIVE SEQUENCE STATOR CURRENT PROTECTION MODE

摘要

A three-phase motor is protected during starting by monitoring the true r.m.s. values of the positive and negative sequence components of the current, using a microprocessor. By using an appropriate model for the thermal equivalent circuit for the rotor a predetermined safe condition may be determined beyond which the motor starting or running action is aborted.