• JNC 154 is a numerical local breaker backup relay, which is used to check the operation of distribution end circuit breakers and to trip feeder end circuit breaker if distribution end circuit breaker fails to trip.
• Its features include wide OC setting range (.5 per cent to 200 per cent), wide time setting range (50 ms to 1.25 sec), fast reset time, high dropoff/pickup ration, history of 5 latest faults.
• The relay is designed to trip the feeder end CB if the protective relay at the distribution end operates but its corresponding CB fails to operate. 
• The current is derived from line CT. The instantaneous trip output contacts operates when the over current exists and the protective relay has operated. The protective relay contact (PRC) input is required. The delayed output contact operates after the selected definite time.