ADJUSTABLE SOLID STATE OVERLOAD RELAY

摘要

Overload and other excessive current conditions as regards an electric motor for example are sensed by current sensing loops which form the primary winding of respective transformers. The voltages developed across the secondary windings are rectified and supplied to a de-energizing circuit. In accordance with the invention a plurality of adjustable potentiometers are incorporated in the said circuit in a unique manner for calibrating the circuit and for limited adjustment whereby it is possible for different magnitudes of current flowing in the conductors to the motor to cause an overload tripping of the device and an interruption in the supply of said current to thus stop operation of the motor. The trip point can be adjusted as much as twenty percent up or down to thus eliminate the problems of heaters and the necessity of stocking a different overload device for every current rating.