GB991868A - High-tension switchgear protected against explosions and firedamp - Google Patents

Abstract

991,868. Switchgear structures; actuation of switches; switch contacts; switch cases. ZAKLADY WYTWORCZE APARATURY ROZDZIELCZEJ. July 10, 1962 [Nov. 28, 1961], No. 26443/62. Heading H2B. A switchgear for use in damp or explosive atmospheres has a casing comprising a cylindrical circuit-breaker chamber 1 and a plurality of isolator and terminal chambers 10, 12 arranged along the base and one side thereof and connected thereto by sleeves 29 which carry insulating bushes 30. The chamber 1 encloses voltage and current transformers 3, 4 and an overload relay 5 besides the circuit breaker 2 and also carries a number of metering and measurement boxes (Fig. 1, not shown). The chamber 1 is closed and sealed by a hinged door 14 which carries a plurality of peripheral projections 18 corresponding with similar projections 19 on the casing, the door being locked by rotating a ring 21 so that projections 22 thereon clamp the projections 18, 19 together. The door 14 carries an actuating mechanism (Fig. 7) having holes 44 engaging with dogs 45 on breaker actuating shaft when the door is closed. To operate the breaker a lever 47 is turned in the direction of the arrows, turning freely about the housing 14; thereafter it is turned in the opposite direction so that the enlarged tip 53 of a pin 51 drives a pivoted arm 47a into the broken line position shown. Slight further movement causes the arm 47a to engage in a groove 54 in the tip 53. Finally lever 47 is again turned in the direction of the arrows, the arm 47a driving the pin 51 against its bias 55 into a hole 50 in part of a sleeve 43 in which are formed the holes 44. Continued turning of the lever 47 causes the sleeve 43 to turn therewith to operate the breaker through suitable springs (not shown). Each chamber 10 contains a three-phase (Fig. 4, not shown) isolating switch comprising a shaft 35 with bosses 35a each having a pair of contact blades 33 supported therein by projections 38 and by a spring 41 and plates 39. The blades 33 are biased together by springs 42 to grip the fixed contacts 34 which are formed directly on the conductors passing through the insulating bushes 30.