Patent GB-410206-A (GB)
Title: Improvements in or relating to metal-clad electric switchgear
IPC: H02B13/02
Filed: 1932-11-17
Abstract: 410,206. Switchgear structures. REYROLLE & CO., Ltd., A., Hebburn-on- Tyne, and ALLAN, A., Cragside, Ashleigh Grove, Tynemouth. Nov. 17, 1932, No. 32529. [Class 38 (v).] Oil - switches ; actuating ; cases ; contacts ; indicators ; interlocked switches ; latching and unlatching.-An isolating switch chamber associated with one or more main circuitbreakers contains insulating liquid and has a top compartment serving to contain both operating mechanism for the isolating switch or switches and acting as a conservator tank for maintaining the chamber filled and for permitting expansion and contraction of the liquid with temperature changes. The invention is shown in its application to switchgear for a high-tension transformer sub - station supplying a ring-main. General lay-out. This is shown for one phase as a circuit diagram in Fig. 3 and as a structure in Fig. 1, in which the remaining phases are placed behind the one shown. Three oil circuitbreakers 60 .. 62 are located between four chambers 63.. 66 containing the isolating switches and connectible thereto bv inclined withdrawable conductors (see 80, 82 in Fig. 3). The inner chambers 64, 65 contain contacts 70 .. 72, of which 72 are connected to the sides of the ring main, and 70, 71 are interconnected by a rigid conductor 90. An isolating arm 91 is pivoted on 70 so as to be engageable with either of 71, 72, and an earthing switch 97 is provided for each contact 72. Chambers 63, 66 contain contacts 75 .. 77, of which 75 is connectible by conductor 82 to the adjacent breaker and serves as a pivot for independently movable isolating arms 95, 96 which are engageable with contacts 76, 77. Contacts 76 are interconnected by a conductor 84 and contacts 77 are connected to the supply transformers 83, an earthing switch 97 being also provided. The isolating and earthing switches are operated from a pedestal 56, the connections being housed in trenches 58 containing the cables. The main breakers are arranged generally as described in Specifications 398,889, 398,890, and 398,891 and provided with operating pedestals 57. Withdrawable conductor arrangements. Extending from each fixed breaker contact (Fig. 6) is a hollow condenser insulator 110 in a metal sleeve 112 carrying a flange 113 for bolting to the outside of the tank. A metal cap 114 makes an oil-tight closure and carries a metal sleeve 115 which engages with the withdrawable conductor 140 by means of contacts 145 in a block 146. A metal casing 120 having a space 122 for current transformers, carries a guard 124 for removable flexible bellows 123 which are secured to the base of a valve chest 130 located below the appropriate isolating switch chamber. The conductor 140 in its operative position projects through the opened valve 131 into the latter and engages a fixed isolating contact therein and also with sleeve 115 and the fixed breaker contact. The conductor comprises a metal tube 141 suriounded by condenser or other insulation 142 and an outer metal sheath 143, and carries flexible leads 144 interconnecting the contact block 146 and the bundle of independently spring-pressed butt contacts 147. The sheath 143 also carries piston rings 148 so that, by admitting oil from an electric-motor driven pump 150, Fig. 1, above or below the rings, the conductor can be operated up or down. The operation of the motor is, however, interlocked with the operating handle of valve 131 by means of a switch, the said handle being also mechanically interlocked with a latch for the conductor 140, Fig. 7 (not shown). The latter latch comprises a ring 160 surrounding the sheath 143 and pivoted at 161 so that flanges on its inner surface engage with their respective grooves 164 (as shown), or 165. When the conductor 140 is to be operated, a rod 175 oscillates the ring 160 and at the same time actuates auxiliary switches 177 and an indicator visible through a window 179. Isolating switch chambers. Each chamber 64, 65 (Fig. 11) contains a contact 72 to which a cable sealing end 181 is connected by contacts 183, an oil-tight joint being effected at the junction of insulator 180 and the casing, and a flange 186 being provided for keeping oil within the insulator. The chamber as a whole is preferably provided with barriers as described in Specification 410,826. Contacts 70, 71 are hemispherical-shaped for engagement by contacts 147 and the hemispherical parts of 71 are in two pieces, through one of which passes the conductor 90. The contact 70 is mounted on rotatable insulator 200 provided with a metal ring 202 from which the arm 91 projects. The top compartment 210 contains operating mechanism and also serves as a conservator tank for oil, for which purposes it communicates with the main chambers by means of small holes 211 which are large enough to carry out that function but are not large enough to interfere with the hydraulic actuation of the withdrawable conductor 140. Their upper ends are on a raised portion of the compartment base so as to keep moisture from passing through, and are preferably provided in a valve which can be raised for initially filling, Fig. 15 (not shown). A window 222 (Fig. 13) enables the oil-level to be seen and a float and indicator alarm 223, 224 announcer when the level is too low. Dry air may be breathed in through a device leading through a pipe to the space above the oil-level in 210. The operating mechanism comprises spindles 260, 270, 280, 290 which are for operating, respectively, a cable-earthing switch, the latch 160 for the conductor 140 and the latch for the operating handle of valve 131 associated with the respective two main breakers, and the rotary insulator 200, the mechanism including the arrangements of links and levers shown in Fig. 13. Each spindle rotates through about 100‹ and is so arranged that the maximum mechanical advantage is attained at the beginning and end of the stroke. The arrangements for the two outer chambers 63, 66 are somewhat modified to suit the different conditions of rotary isolators and involve a pair of independently-movable concentric insulators, Fig. 19 (not shown) for operating the two isolating arms 95, 96. Cable-earthing switch. The spindle 260 is connected by lever 262 and link 263 to a crank 264 on a counterbalanced toothed quadrant 236 (Fig. 16). The latter drives a pinion 235 operating on a rack 234 on a sleeve 233 which houses a plunger 230, the lower end 231 of which moves in insulator 188 into engagement with a seating 187 on contact 72, a valve surface 250 being also provided to make an oil-tight joint when 230 is in the inoperative position. In the operative position a contact 237 at the head of 230 engages a shoulder 238 and so earths contact 72. Adequate pressure in both positions is provided by two springs 239, 246 connected between the sleeve 233 and the plunger 230 and contact 237. The casing 232 has a window 252 through which an indicator 253 may be seen, the indicator being carried on a squared rod 254 which is twisted at 255 so that a nut 256 on the plunger is caused to slide on the rod and to rotate it at the end of the down, and beginning of the up, stroke. Operating pedestals. Spindles 260 &c. are connected by universal couplings 351 to shafts 350, Fig. 11, extending to trenches 58 where they are connected to horizontal rods 357 for coupling together the mechanism of the several phases and bringing out each to an operating socket 401 on the top of the pedestal 56. Thus each pair of rods 357 is connected by linkage, as 358, 371, to a shaft, as 370, terminating in a socket provided with padlock means 402, 403, and an indicator 404, 405 and adapted to receive an operating rod. Each spindle also carries a crank arm 410 operating switches 413, 414 in the circuits of the motor of pumps 150, so that the latter may be energized, provided switches 177 are operated by the latches 160 and provided the valves 131 are open. A disc 362 on the spindle of the cable-earthing switch engages a similar disc on the spindle of an isolating switch to prevent operation of the former to the earthing position until the latter has been moved to the isolating position. The remaining spindles carry discs 420 engageable by a latch 421 on an arm 422 operated by the armature 423 of a coil 424, the circuit of which is closable by a press-button 425 in series with other interlock contacts ; the lever 422 also operates an indicator 426 for showing the position of the latch. Slightly modified forms of interlock are necessary for the remaining spindles of the outer pedestals. For low voltages the separate phases are all combined into one main breaker and isolating chamber, having a single sluice valve with three separate ports. For a duplicate busbar system, five main breakers would be necessary. Specification 410,207 also is referred to.