This means that when inserting and removing the test plug, any connected CT circuits cannot become open circuit and therefore cannot contain a potentially life-threatening high voltage across the open circuit CT contacts.
Part of PowerLogic
MiCOM P991 test block offers safe and preconfigured facilities for monitoring and secondary injection testing in any power system protection scheme. To be used with MiCOM P992 Test plugs. Models available: MiCOM P991, MiCOM P992, MiCOM P993