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MS-2 Circuit Breaker & Overload Relay Test Set

Supplier: Maceys Electrical

Product Features and Benefits

Price Guide (Inc GST): POA

  • Digital memory ammeter: High-accuracy, direct reading instrument has read-and-hold memory for measurement of short-duration currents.
  • Digital, multi-range timer: Crystal-controlled, high accuracy instrument with autoranging measures operating time to 1 millisecond.
  • High-current output: Provides instantaneous currents up to 750 amperes through a 125 ampere breaker.
  • Solid-state output initiate circuit: Solid-state circuit eliminates need for contact maintenance.
  • Portable, high-current test set: Unit weighs only 33 lb (15 kg) and is tough enough to withstand daily field or plant use.


The MS-2 test set is used around the world by several thousand utility companies, industrial plants and electrical service organizations.

Using the latest technology, Model MS-2 is a self-contained test set that incorporates a variable high-current output and appropriate control circuitry and instrumentation for testing thermal, magnetic or solid-state motor overload relays; molded-case circuit breakers; and ground-fault trip devices.


Model MS-2 is capable of testing the time-delay characteristics of 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.

Additional applications include verifying the ratio of current transformers and testing panel-board ammeters and voltmeters.