EHT electrical plant earthing system - uses actuator and cooperating contact arranged at earthing points of plant, with blocking device to provide triggering only following releas

摘要

An extra-high tension (EHT) plant earthing system is suitable for max, short-circuit currents of 100-200 kA and thermal short-circuit currents of 40-100 kA for plants operating at rated voltages of 123/245 and 420kV. The system is designed to solve the problem of safe and reliable earthing without involving the high cost of installing conventional remotely operated earthing switches at all earthing points. An actuating mechanism (1) is used for an earthing device only connected into the system when the need arises, and a cooperating contact for the earthing device is arranged at the earthing points of the E.H.T. plant. The actuating mechanism contains a blocking device that allows triggering only following release. The actuating mechanism contains a weight compensation facility.