GB817804A - Improvements in and relating to flame-proof electric switchgear - Google Patents

Abstract

817,804. Two-part couplings combined with switches. METROPOLITAN - VICKERS ELECTRICAL CO. Ltd. June 12, 1957 [March 12, 1956], No. 7663/56. Addition to 727,664. Class 38 (1). [Also in Group XXXVII] In a modification of the flameproof switchgear described in the parent Specification, the casing 6 carrying the socket 20 and enclosing the isolating switch 14 by means of which the socket may be connected to the battery, also encloses a control switch connected in a pilot circuit controlling the energization of a charging cable, the two switches being interlocked so that the isolating switch can be operated only when the control switch is " off " and the control switch cannot be closed when the isolating switch is open. The control switch comprises fixed contacts 201, 202 and a bridging contact 204 spring-urged towards the fixed contacts and moved away from them by a tappet 210 carried by a pivoted arm 207 carrying a roller 217, the arm being urged by a spring 207a so that the roller engages a notched cam 214 carried by the switch-operating spindle. In the position shown, the control switch is open, the roller 217 engaging a notch 217 in cam 214, and an attempt to close the switch by turning cam 214 anticlockwise will cause a lug 219 on arm 207 to engage the surface of an interlocking sector 220 carried by the operating spindle 9 of the isolating-switch 14 which is shown in the open position. Closure of the control switch is thus prevented. If, however, the isolating switch occupies either of its " test " or " run " positions, with a plug inserted in socket 20, one of two notches 221, 222 in the sector 220 will be aligned with the lug 219, thus permitting pivotal movement of the arm 207 by the cam 214. In the closed position of the control switch, roller 217 engages a shallower notch 215 in the cam which holds the tappet 210 raised and allows the contacts 201, 202, 204 to close. With the lug 219 occupying either of the notches 221, 222, the isolating switch cannot be moved without first opening the control switch.