Electric distribution line ground fault prevention systems using dual parameter monitoring with high sensitivity relay devices

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

• A. a three-phase electric distribution line system having a plurality of circuit breaking devices and transformers;
• B. a plurality of relay devices connected to said distribution line system, said plurality of relay devices having a best sensitivity for measuring line instantaneous undercurrent of at least 0.01 amps or lower amps, and thereby being high sensitivity relay devices, wherein at least some of said plurality of relay devices are connected to at least some of said plurality of circuit breaking devices;
• C. a programmable relay protection system functionally connected to said three-phase electric distribution line system, including functionally connected to said plurality of relay devices on each line of said electric distribution 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 negative sequence overcurrent;
• 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 breaking device on a broken line when that line shows said at least two operating conditions are outside said preset parameter ranges;
• e) and completing the sensing and tripping within 1.0 second.