Electric transmission line ground fault prevention systems using dual, high sensitivity monitoring devices

A system for preventing ground fault or other short circuit in a three-phase electric transmission line system having at least three lines, caused by a break in a line, which utilizes at least dual high sensitivity monitoring, which comprises:

• A. a three-phase electric transmission system having at least three lines and a plurality of circuit breakers;
• B. a programmable relay protection system functionally connected to said three-phase electric transmission system, including a plurality of relay devices on each line of said electric transmission line system, said relay protection system being programmed to include:
• a) preset parameter ranges of at least two high sensitivity electric operating conditions, said preset ranges being acceptable operating parameter ranges, one of said operating conditions being instantaneous undercurrent, and one other of said operating conditions being selected from the group consisting of a) line differential overcurrent;
• b) negative sequence overcurrent and C) combinations thereof;
• b) monitoring means to monitor each line at each of said plurality of relay devices for said at least two operating conditions;
• c) permitting closed circuit operation when all of said lines show said at least two operating conditions are within said preset acceptable operating parameter ranges;
• d) sensing open conductor broken line changes and tripping a circuit breaker on a broken line when that line shows said at least two operating conditions are outside said preset parameter ranges;
• e) and completing the following steps B. and C. within 1.0 second;
• C. a communications system for communications between said relays and said circuit breaker such that when said relay protection system senses an open conductor broken line when said at least two operating conditions fall outside of said preset parameter ranges, communicating to open the circuit breaker on said broken line, thereby shutting down power to said broken line before it otherwise causes a ground fault or other short circuit.