MS-2A Circuit breaker and overcurrent relay test set

The cost-effective solution for testing circuit breakers and over-current relays.

MS-2A has the capability to test the time-delay characteristics of overcurrent relays, motor overload relays, and molded-case circuit breakers.

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Rugged and lightweight

Unit weighs only 33 lb (15 kg) and is tough enough to withstand daily field or plant use.

Digital memory ammeter

High accuracy, direct-reading instrument has read-and-hold memory for measurement of short duration currents. Ideal for testing ground fault devices, overcurrent relays and molded-case circuit breakers.

Digital, multirange 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 in a small 33lb (15kg) package.

Full Product Details

About the product

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.

FAQ / Frequently Asked Questions

What is the current threshold to start and stop the timer?

The threshold is approximately 8% of the current range. Therefore the current range should be set on at least 10% of the current used for the test.

What input voltage is required?

The MS-2A can be ordered as a 120V or 240V 50/60 Hz single phase unit. You must specify which version (120V or 240V) at the time of order.

What does display in Normal or Memory mode mean?

Normal mode displays the real time current being measured, where memory displays the peak current seen since last reset.

The MS-2A has a terminal for ground. Is this required to be grounded?

The MS-2A is grounded from the ground wire in the input power cord. The ground terminal is only provided as an additional point to ground if required by the customer.

What is the maximum current output of the MS-2A

The maximum output is 750 amps for 30 seconds or 240A for 30 minutes.