HIGH-VOLTAGE POWER NETWORK WITH LOW GROUND CURRENTS Russian patent published in 1995 - IPC

FIELD: electrical engineering; surge-voltage protection of 3-335 kV networks when handling inductive currents. SUBSTANCE: high-voltage power network with low ground currents has electric motors connected to buses through three-phase vacuum-type switches one of whose phases is connected in parallel with single-phase voltage selector permitting action of linear voltage for time sufficient to clear single-phase ground fault. Single-phase voltage selector may be installed in parallel with phase first to turn off and two selectors of protection degree 1.7-1.8 for maximum linear voltage of network may be inserted between switch phases on motor side. Phases of vacuum-type switches shorted out by single-phase voltage selectors may be also connected to one phase of collecting buses. Voltage selectors are mounted on draw-out part of metalclad switchgear cubicle. EFFECT: improved reliability of network operation due to reduced surge voltage across working vacuum-type switches. 5 cl, 1 dwg