Protecting Motors

Sprecher + Schuh has released an application integrated circuit (ASIC) in its CEP 7 overload relay that has features not possible with traditional bi-metallic or electromechanical overload relays.

Unlike traditional overload relays that simulate heat build-up in the motor by passing current through a heater element, CEP 7 measures motor current directly through integrated current transformers.

These create a magnetic field that induces DC voltage onto the ASIC board. The electronics identify excessive current or loss of phase more accurately and react with greater speed and reliability than traditional overload relays.

The CEP 7 is self-powered. It develops the power it requires from the applied voltage.

Other features of the relay include a choice of different tripping classes, 10 or 20 and a choice of reset options, which can be either manual or automatic.

An additional feature is the separate trip contacts (N/O, N/C) and the overload relay dissipates much less power than traditional bi-metal overloads (150 mW versus 4-6 W).