Circuit breaker and overcurrent relay test set

Product Documents
  • Crystal-controlled, high-accuracy instrument with autoranging
  • Measures operating time to 1 millisecond
  • Lightweight and portable primary injection test instrument
  • Desgined for overcurrent relay testing
  • High current output
  • Earth/ground fault performance testing for NEC 230.95

The MS-2A circuit breaker and overcurrent relay test set is one of our more popular test set and has been used around the world by several thousand utility companies, industrial plants, and electrical service organisations. This relay tester is capable of testing the time-delay characteristics of overcurrent relays, motor overload relays, and molded-case circuit breakers rated up to 125 amperes, when following the recommended test procedure of testing the time delay of these devices at three times their rating.

Higher currents are available for the short durations required to test an instantaneous trip element. For example, the test set will provide a maximum short- duration output of 750 amperes through a typical, 125 ampere, molded-case circuit breaker. The MS-2A is ideal for testing earth/ground fault protection devices with window CT’s. The NEC 230.95C requires specific earth/ground fault devices be performance tested when initially installed.

Technical Documents
Technical guide
Ground Fault Protection Testing per NEC 230.95(C) of Low Voltage Circuit Breakers