In order to compare the currents entering and leaving the protected zone of 2 differential feeders, MCBI relays were made. MCBI made it its mission to compare and transmit information between two different relays. Each piece of relay is capable of comparing the current at its respective end. The pilot wire transmits analog circulating current, this allows precise procedure even for low specification or ageing pilots. MCBI relays are also famous because of its high level of stability even through faults. It also has a low current transformer requirement made for added convenience. This world class innovation can operate fast for in zone faults and and this equipment is also well known for simultaneous tripping of relays at each line.