Multi-Amp/Megger MS-2 Circuit Breaker Test Set

Multi - Amp/Megger MS - 2 Circuit Breaker Test Set
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Multi-Amp MS-2
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Datasheet Specifications
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.


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


Input 120 volts OR 240 volts, 50/60 Hertz single-phase
Output Ranges 0 to 120 volts at 5 amperes
0 to 24 volts at 25 amperes
0 to 6 volts at 120 amperes
0 to 3 volts at 240 amperes
Output Capacity The test set is capable of testing the time delay characteristics of devices rated up to 125 amperes using a test current of
three times their rating (375 amperes). Additionally, to perform an instantaneous trip test, it will provide 750 amperes
through a typical, 125-ampere, molded-case circuit breaker connected with the test leads provided with the test set
Ammeter Display: 3½-digit
Ranges (switch-selected): 0 to 1.999/19.99/199.9/750 amperes
Timer Display: 5-digit
Ranges (switch-selected):
A. 0 to 99.999 seconds
B. 0 to 999.99 seconds
C. 0 to 99999 cycles
Timer Control Circuit A. Current Actuated
B. Normally Closed
C. Normally Open


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 shortduration output of 750 amperes through a typical, 125 ampere, molded-case circuit breaker. Additional applications include verifying the ratio of current transformers and testing panelboard ammeters and voltmeters.