Abstract: A polyphase reversal detection and correction system which operates over a wide range of line frequencies and produces an automatic phase correction for maintaining proper phase sequence to a rotating device. The system includes a circuit arrangement for developing peak integrated signals by comparing the relation of various input phases, and developing an integrated reference phase signal. The input phase signals and the reference phase signals are compared to determine and correct the input phase sequence.

Abstract: A system for protecting a three-phase motor is disclosed. The system includes a signal conditioning circuit which senses the magnitude of current flowing through each motor phase and generates a single-line, three-phase voltage output signal having each of its phases corresponding to a single motor current phase. This three-phase voltage output signal is efficiently utilized by a microcomputer system to detect motor current overload and motor current imbalance. The microcomputer system instructs a motor controller to shut down the motor in response to a motor current overload or motor current imbalance.