BUILT IN TEST (BIT) FOR TRANSFORMER RECTIFIER UNIT (TRU) BACKFEED INTERLOCK

A method includes performing a test for transformer rectifier unit (TRU) backfeed protection by removing AC power supplied to the TRU but keeping the TRU contactor closed for a first predetermined span of time. The method includes observing the TRU for a second predetermined span of time. The method includes determining if the contactor opens during the second span of time, that a TRU backfeed protection is functional and passes the test, and determining if the contactor does not open during the second span of time, that the TRU backfeed protection has failed the test.