Numerical Local Breaker Back-up Protection Relay : ALBB3General DescriptionThe ALBB3 is a 3 OC and 1 EF design as Local Breaker Back up. This relay monitor feeder current and feeder relay contact. If feeder relay fail to clear fault with in pre define time then this relay provide trip command to all connected incoming feeder and safeguard against fault hazards. 4 Element (3 Phase + EF) current sensing with internal timer. Display of fault current. / Load current. Instant reset. Very low Burdon on CT.