Patent GB-498729-A (GB)
Title: Improvements in or relating to electric circuit breakers suitable for high tension circuits
IPC: H01H33/02
Filed: 1938-04-29
Abstract: 498,729. High-tension switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO. April 29, 1938, No. 12849. Convention date, April 30,1937. [Class 38 (v)] A circuit-breaker for highvoltage power circuits comprises a casing consisting of a tubular member of vitreous or other insulating-material and a metal housing or structure, preferably grounded, for supporting the member, and a line terminal supported on one end of the tubular member. A unitary contact assemblage is disposed within the casing and has at least one pair of relatively movable contacts and actuating means therefor, one contact of the pair being adapted to be connected to the said line terminal, and means being provided for removably mounting the contact assemblages in the casing. The breaker casing comprises substantially tubular columns 21, 23 clamped to an openended metal housing 19 carrying trunnions 25 by which the casing is pivoted in bearing plates 15 of the metal supporting structure 9, so as to be located either in a vertical position, Fig. 2, or a horizontal position, Fig. 3, in which it is secured by bolts 29 engageable with either of two sets of holes in plates 27 secured on the plates 15. Extending through the breaker casing is a moulded insulating tube 35 which is drilled at its upper end to receive the contact assemblage and has a flanged metal ring 37 secured to it and to a C-shaped resilient expansion ring 31, which abuts also on the column 21 and carries a line terminal 33. The contact assemblage comprises a plurality of serially-connected devices 43, a disconnecting switch 45, and actuating means 47 for separating them, the arrangement being such that circuit is originally broken, and finally made, at the devices 43, for which purpose the individual movable contacts of the devices are operated by a common central rod through straight-line linkage, a throw-off spring being provided at the base of the rod. Suitable forms of device 43 having arc-extinguishing arrangements are described in Specifications 472,721, 479,412, and 479,728. To remove the contact assemblage, bolts 103 are removed from ring 31, whereby the cap 81 carrying the assemblage is freed. When the assemblage is removed, contact is broken between a fixed contact 106 and companion female contact on the assemblage. One contact of the upper device 43 is connected to a contact 71 of the disconnect switch 45, which contact is engageable by a vertically movable contact 83 having a pin-and-slot connection with an arm 85 pivoted in a cap member 81 which is flexibly connected at 86 to contact 83 and is connected to terminal 33. An accelerating tension spring 87 acts on contact 83 to accelerate the opening movement. The voltage-drop may be equally distributed across the individual devices 43 by condenser shields (not shown) in the upper part of member 35, and stepped and spaced condenser foils are embedded in the lower part of that member to insulate from casing 19 the conductor 105 extending between contact 106 and the lower terminal 107. An expansion ring 109 is placed between a nut 110 and the lower end of the insulator 23, which ring. together with ring 31, permits relative expansion between the insulators 21, 23 and the tube 35 and conductor 105. When the breaker casing is oilfilled, a filler inlet 115 and drain plug 117 are provided, and rubber or cork gaskets 119 are located at the various joins. A current transformer 113 is housed in the interior of central housing 19. The free end of lever 85 is connected by insulating rod 121 to a shaft 125 which is operated by linkage 127, 129 and rod 131 from mechanism in a casing 133. The mechanism may comprise a motor or solenoid closing means, retaining latch, trip means, and throw-off spring, and may be common to a plurality of breaker-units.