The purpose of secondary injection testing is to prove the correct operation of the protection scheme from the relay input terminals onwards. Why done prior to primary injection tests? This is because the risks during initial testing to the LV side of the equipment under test are minimized.

Circuit Breaker Secondary Injection Testing is an alternative to the standard Primary Injection Testing. Secondary injection testing can be carried out if Primary Injection Testing is not possible or only the trip function requires to be tested. These tests prove the trip units operation are within the manufacturer’s trip time curves.

Modern Circuit Breakers have test points located in the trip circuit to allow for manufacturer specific tests sets to be used in proving the trip circuits. These units simulate the trip circuit currents to ensure the trip units operate as intended. Older circuit breaker designs can be the open wiring design type where the trip circuits are accessible and the standard secondary injection test sets can be used.

At PQE Power System, we offer test set OMICRON356 as the universal solution for testing all generations and types of protection relays. Its powerful six current sources with a great dynamic range, make the unit capable of testing even high-burden electromechanical relays with very high power demands. Unit is also accompanied by a full Relay toolkit including specific manufacturer’s test blocks, test probes, resistors, multi-meters and various hand tools.

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