TESTER FOR A PLURALITY OF CIRCUIT BREAKERS HAVING A RANGE OFRATED CURRENTS AND MULTIPLE TRIP FUNCTIONS

摘要

A tester for in situ testing of a plurality of circuit breakers having a range of rated currents and multiple trip functions, includes a plurality of power resistors of known impedance, an electronic switch associated with each powe r resistor connecting the resistor in series with the load terminal of the circuit breaker under test, and a controller that turns on a number of the switches selected to collectively draw through the associated power resistors a test current that is a function of the rated current and sufficient to trip the circuit breaker within a selected time window. Turn on of the electronic switches is also controlled to genera te a current waveform appropriate for the trip function being tested. In a self test mode, the value of each of the power resistors is verified as being within limits.