Patent GB-898462-A (GB)
Title: Load break disconnecting switch
IPC: H01H33/12
Filed: 1958-12-02
Abstract: 898,462. Air-brake switches; gas-blast switches; switches held set and freed mechanically; contact members for switches. S. & C. ELECTRIC CO. Dec. 2, 1958 [Dec. 23, 1957], No. 38802/58. Class 38 (5). In a load-break disconnecting switch arrangement, the movement of an operating member in one direction first trips a latch to permit spring means to open interrupter contacts, then opens the disconnecting switch blade and finally recloses the interrupter contacts and restresses the spring means, subsequent reverse movement of the operating member closing the switch blade while the interrupter contacts remain closed and the spring means stay stressed. Air-brake switches.-The disconnecting switch has a blade or arm 25, Fig. 5, which may be swung to the open or closed position and turned about its longitudinal axis to initially disengage or to finally engage the contacts. The arm 25 has an arcing tip 42 co-operating with arc horns 43, 44 which are staggered to facilitate ice breaking. The arm also has laterally extending contact " ears " 51, Fig. 6, which co-operate with bifurcated inner limbs 52 of U-shaped fixed contacts 53 which are inwardly biased by springs 58, the spacing and stressing of the limbs of the contacts being determined by a spacer 61 and an equalizer bar 63. The ears 51 and the limbs 52 may have silver alloy inlays. Oas-blast switches.-The load-break switch or interrupter 23 comprises a plurality of seriesconnected main " breaks " and plurality of series-connected auxiliary " breaks " connected in parallel with the main breaks. Each auxiliary break, Fig. 20, comprises a fixed tubular contact 183 which is slotted to form fingers 184 inwardly biased by a contact spring 185. The movable contact 222 is connected by a bayonet coupling 224 to an operating rod 171 and by a pin 268 to a rod 266 carrying a gas evolving trailer 270, the contact 222 being drawn into a gas-evolving liner 239 when the interrupter is opened. Each main " break," Fig. 22, comprises tubular fixed contacts 164, 201 which are slotted to form fingers 165, 202 inwardly biased by springs 166, 203, and provided with rings 165<SP>1</SP>, 202<SP>1</SP> to limit their inward movement. The movable contact 197 has portions 198, 199 which co-operate with the fingers 165, 202, and is moved to the right by an operating rod 169 to open the circuit between contacts 164, 201. Each main " break " is surrounded by a voltage dividing resistor 191. Switches held set and freed mechanically.-The arrangement is operated by a rotatable insulator 17, Fig. 5, toggle linkage 28 and a rod 37, Fig. 12, pivoted to an operating handle 39. The handle 39 is fixed to a shaft 120 carrying an over-centre toggle linkage with a pawl 137. When the handle 39 is turned in the clockwise direction to open the switch arrangement, the toggle linkage is moved over-centre to raise the pawl 137 so that it rides over ratchet teeth 136 and prevents any attempt to reverse the direction of movement of the handle until the full opening sequence of operations has been performed. The insulator 17 carries a shaft 21 which extends through a mechanism housing 22 to an operating lever 68 of the disconnecting switch arm 25. Within the housing 22, Figs. 34 and 35, a cam 310 is secured to the shaft 21 on which are rotatably mounted an auxiliary break-operating lever 346, a main breakoperating lever 324 and a " pry-out " cam 374. When the shaft 21 and cam 310 are turned in the anticlockwise direction to perform an opening sequence of operations, a detent 310a moves a latch arm 312 which moves a latch 314. The latch 314 releases the lever 324 which turns in a clockwise direction under the bias of springs 332, 333 to open the main breaks first. As the lever 324 turns, a pin 368 mounted on it moves a latch arm 411 aside to release the lever 346 which opens the auxiliary breaks. After the shaft 21 has been rotated sufficiently to open the disconnecting switch arm, a detent 408 on an arm 410 of the cam 310 moves the levers 324, 326 back in the anticlockwise direction to a position in which they are re-latched, this return movement reclosing the main and auxiliary breaks of the interrupter and restressing the springs 332, 333. The pry-out cam 377 is operated to apply a positive start to the lever 324, should the interrupter contacts stick, when a detent 310a<SP>1</SP> on the cam 310 turns a lever 380. A plurality of detents is provided on the cam so that reversal of the operating handle towards the end of its closing movement causes the full opening sequence to occur. Specification 898,463 is referred to.