A circuit breaker is a manually or automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow. In addition to providing a means to open and close its contacts manually, a circuit breaker must automatically open its contacts when an overcurrent condition is sensed.
The trip unit is the part of the circuit breaker that determines when the contacts will open automatically.
In a thermal-magnetic circuit breaker, the trip unit includes elements designed to sense the heat resulting from an overload condition and the high current resulting from a short circuit.
The Cutler Hammer 140D481G03 Secondary Injection Test Set is used to test and verify the pickup levels and time delay settings of a breaker’s trip unit. The Cutler Hammer 140D481G03 is also used to test Amptector, Digitrip, RMS or Optim trip units.