GB1459603A - Medium voltage switchboard more particularly for feeding of a transformer substation - Google Patents

Abstract

1459603 Switchboards; gas blast circuit breakers MERLIN GERIN 14 Aug 1974 [30 Aug 1973] 35875/74 Heading H1N A switchboard particularly adaptable for ring main and T-junctions comprises a plurality of adjacently disposed air insulated cells, Fig. 1 (and Fig. 8, not shown), each cell including an air insulated busbar compartment 22, Fig. 3, and a three-pole horizontally arranged puffertype circuit-breaker in an insulating gastight enclosure 26 filled with electronegative gas, which enclosure forms a horizontal portion of a partition wall between the busbar compartment and the rest of the cell. Additional equipment for individual cells can comprise an earthing switch 74, protective line fuses 72 for the outgoing equipment and a variety of alternative cable entry and termination means. The puffer-type circuit-breaker, Fig. 10, has a monobloc-type moulded housing 118 with a sealed rear cover 114, and with an internal mounting member 142 for the movable contact rods 132 there is formed a rear compartment 111 in which a common drive shaft 124, individual insulating cranks 126 and link couplings 128, 130 for each pole are situated, the contact rods being connected to busbar side terminals 40, 42, 44 of the circuit-breaker by flexible braids 154. In a front compartment 116 the end face 140 of the housing supports incoming terminals 34, 36, 38 and fixed contacts 136 whilst the puffer device comprising a piston, nozzle and aperture assembly 146, 148, 150 is secured by the movable contact 134 to the contact rod 132 and cooperates with an open-ended cylinder 144 integral with the member 142. The rear compartment 111 also contains an earth bar 156 more closely spaced to the live link coupling 130 than the separated distance of the two contacts 134, 136 so that an excessive voltage rise on the busbar side will flashover to earth rather than across the contacts when the breaker is open.