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Electrical SwitchgearBy : Suraj - 11-Apr-2018 
What is Primary Injection & Secondary Injection testing of a Circuit Breaker?
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Diptimayee 11-Apr-2018

Primary & Secondary injection test for a ckt breaker is carried out to check the behavior of ckt when its deals with the various load.
as we know that ckt breaker works on the basis of the command given to it. That command generally is given by the Trip unit which gets date/value from CT. Primary injection test is carried out for a breaker which having Thermal Magnetic & electronics trip unit, Whereas Secondary injection test is carried out for the breaker which has only electronics trip unit.

primary injection test involves details connection testing from CT to trip unit along with individual CT, trip unit testing, but in case of secondary injection, we need to carry test for the only trip unit.

Primary injection test required more expertise as compared to secondary injection test.