GB879514A - Improvements in or relating to isolators for electric switches - Google Patents

Abstract

879,514. Air-break switches; oil-break switches; switchgear structures. GENERAL ELECTRIC CO. Ltd. May 19, 1959 [June 27, 1958], No. 20678/58. Class 38 (5). An isolator suitable for use with the oil circuit-breaker described in Specification 879,511 is arranged to be plugged into and interlocked with the latter in place of the breaker coverplate. To facilitate this an insulating base 5 is mounted over the breaker cable terminals 4 and carries fixed contacts 11 connected to the latter. An insulating wall 7 carrying insulating boards 10 is secured to base 5 and carries fixed contacts 14 and cable cleats 15, contacts 11, 14 having a double-spring V-shape. The isolator comprises a housing 1 carrying an insulating base 18 from which project fixed knife contacts 16 to engage contacts 14 through holes 9 in an insulating member 8. Base 18 also carries fixed conductors 22 which slidingly engage the spring- controlled ends of moving contacts 23 mounted on a rotatable bar 25, the other ends of these contacts engaging the fixed contacts 11 when the isolator is closed. In this position closure of the breaker causes a slot 30 in a metal plate 29 of the breaker latching mechanism to engage a pin 31 on a plate 32 rotatable with the bar 25, thus preventing the opening or removal of the isolator. This arrangement also prevents closure of the isolator when the breaker is closed, by the engagement of pin 31 with the top of plate 29. Contacts 16, 22 may be connected by shorting strips or by high-rated cartridge type fuses and screened instruments may be fitted to the isolator if desired. The isolator may alternatively be plugged into the side or back of the breaker. Specification 879,513 also is referred to.