In power utilities like TSSPDCL, it is a regular practice in 33/11KV indoor and outdoor substations that various electrical equipments like HV breaker, LV breaker, feeder breaker, battery charger, etc., are supplied with AC/DC supply through fuses. Substation operators are instructed by in-charge officers to regularly monitor the availability of power supply to these equipments through indicating bulbs, healthy trip circuits, trip supervision circuits, toggle switches, etc. But, most of the operators hardly check these power supplies to equipment. Sometimes indicating bulbs and meters do not function.
Protection equipment like circuit breakers will not function on non-availability of DC supply, which will not trip on faults and cause damage to equipment under protection. This will results in tripping of backup protection equipment i.e., pulling out LV breaker or pulling out breaker at EHT substations, causing unnecessary interruption to more number of consumers. If this failure of fuse is recognized by the operator in advance by some proper indication and annunciation system these kind of interruptions can be avoided and also burden of MRT staff coming from distance location for replacing the fuse and CBD staff arranging back feed to the feeders will be eliminated.