Patent GB-460971-A (GB)
Title: Improvements in or relating to electric circuit-breakers
IPC: H01H33/75
Filed: 1935-08-06
Abstract: 460,971. Switchgear structures; liquid-blast switches. REYROLLE & CO., Ltd., A., ALLAN, A., and WILLIAMS, T. Aug. 6, 1935, No. 22130. [Class 38 (v)] Cases and covers ; indicators.-A three-phase, liquid-insulated circuit-breaker has the three sets of contacts respectively in the three phases disposed in generally symmetrical triangular formation in a single cylindrical tank and the two lead-in conductors leading to the contacts in each phase are arranged concentrically with one another in a bushing insulator carried by the tank-cover plate, the whole breaker being withdrawable vertically from a fixed upper chamber having contacts with which the lead-in conductors make plug-and-socket, connection. The invention is particularly adapted to metalclad switch-gear for controlling tee-connections from bus-bars which are normally in series with a ring main or other circuit, liquid-insulated isolating switches (capable of opening under load) being provided for disconnecting the ends of the bus-bars from the ring main or other circuit. In this arrangement, the breakers may be mounted side-by-side in a row with the bus-bars passing through fixed upper chambers into the isolating-switch chambers, which are disposed at the ends of the row and receive the cables constituting part of the ring main or other circuit. Figs. 1-3 show the lay-out of a panel each comprising a fixed cubicle 1 housing a breaker 2 which is vertically withdrawable from an upper chamber comprising a bus-bar chamber 4 and a chamber 5 for the tee-connection 19 and associated current transformers 18. The tee'd circuit is connected by leads 15, 17 to the inner 9 of two concentric insulated socket contacts for each phase contained in orifice insulators 7 in the base of the upper chamber. The outer socket contacts 8 in chamber 4 have metal clamps 10 constituting the bus-bars extending on either side to fixed isolating contacts 11 in chambers 12, 13. The cylindrical oil-tank 20 of the breaker carries on its cover 21 three pairs of concentric lead-in conductors 22, 23 surrounded by concentric bushing insulators 24, 25 and adapted, when the breaker is in operative position, to engage contacts 8, 9. The contact-sets are spaced apart symmetrically in triangular formation and radial barriers 27, Fig. 5, are located in the tank 20 to separate the phases. An arc-control device, Figs. 8-11 (not shown), of the character described in Specification 460,219, [Group XXIX], is located in each of the compartments formed by the barriers, and the vents are arranged to exhaust against the barriers. Each movable contact 40, Fig. 5, is connected by an insulating arm 76 to a commom, centrally-disposed, operating rod 78 which is lowered to open the circuit, the rod being linked at 80 to a lever 81 which is pivoted at 82 and has a dashpot 86 to cushion the opening stroke. Lever 81 is linked at 83 to a lever 84 on an operating shaft 85, the arrangement providing increased mechanical advantage at the end of the closing stroke. The rear end of shaft 85 carries a crank arm 87 to which is connected a kick-off spring 88 in a housing 89 pivoted to the cover 21 of the breaker. By supporting the operating mechanism thus on the cover 21, the entire breaker can readily be detached for inspection. The shaft 85 is linked at 123 to a crank arm 122 on a parallel shaft 12<1>, Fig. 5, which controls an indicator 124 and a set of auxiliary switches in a box 125 on cover 21, the connections of the switches being brought up to terminals 126 which, when the breaker is in operative position, engage spring clips 127 on the base of chamber 4. The cubicle-front is closed by a lower plate 160 hooking over flanges 162 at the sides of the cubicle and having a latch 163 engaging an upper door 164 provided with a pair of lugs 165, Fig. 17, each carrying a hinge pin 166. When the door is closed, Fig. 2, each pin 166 rests in a slot 167 in the front of a guide bar 168 extending from front to back of the cubicle, and to open the latter, plate 160 is lifted out and plate 164 swung up on pins 166, which engage the slots 167 and allow the plate 164 to be pushed in a little, in which position it is held raised. When the breaker is lowered, the plate 164 can be pushed right in, Fig. 17, to shut off the contacts 8, 9, but in order to permit testing of the tee'd connection by an authorized person, the plate 164 has three holes just large enough to permit access to contacts 9, the holes being normally covered by a padlocked rotatable shutter 170. The plate 164 also has three windows, one for viewing the indicator 124, another for applying an operating handle 113, and a third for giving access to a hand-trip arrangement 105. The front wall of the upper chamber 4, 5 is occupied by a swing frame 174 which carries the meters 175 and is pivoted on an intermediate frame which is withdrawable to give access to the interior. The movable isolating contacts 178 carry parts which are in continuous contact with contacts 179 which, in the case of the right-hand side of Fig. 1, connect with the ring main. The contacts 178 are mounted on a shaft 177 for rotation from the " on " position shown either to a testing contact 187 or to an earthing contact 190. When the switch is in the earthing position, the cover 189 of an orifice insulator 188 may be opened to permit insertion of a testing contact for the ring main cables connected to contact 179, the operating handle 193 being for this purpose allowed to move back to the testing position. The reverse process is carried out in order to close the cover 189 and reconnect the ring main to the bus-bars, Figs. 20-23 (not shown). The chamber 13 contains a similar isolating switch leading to bus-bar connections 184 in compound-filled boxes 183 for connection to an adjacent panel. With a number of panels, however, the isolating chambers can be omitted and the bus-bar chambers can be arranged to form a continuous chamber extending along the row, with the ends of the clamps 10 connected together and isolating switches at the ends for connection to a ring main. The tanks 20 for the circuitbreakers are formed with cover-joints as described in Specification 460,970,comprising, Fig. 5, a projection 155 on the cover 21 fitting snugly within the thickened upper part 156 of the tank, the cover being secured by four studs 154 passing through lugs 157 and serving to compress a wedge-shaped, packing ring 159. For raising and lowering the breaker, the cover 21 carries a plate 129 in a slot 130 in which is slidable a bar 131, which has a transverse shaft 134 guided at 135 and supporting a foot 136, which is rotatable between the Fig. 2 and Fig. 17 positions by means of a tommy bar applied to socket 137. As the foot 136 is swung down, a cam 139 engages a floor pad 138, so raising the bar 131 until a pin 132 engages a register hole 133 in the base 6, so locking the top of the bar. In the extreme position, the cam 139 latches over the pad 138 to drop the bar 131 and lock it against movement when supporting the breaker, the drop being inadequate to free pin 132 from hole 133. The bar 131 has a hole 148, Fig. 2, and a hole 143, Fig. 17, and the plate 129 has a hole 144, the holes 144, 148 being in alignment in the Fig. 17 position and a pin 145, Fig. 12, being passed through them so that the bar and breaker can be wheeled together into the cubicle. The pin 145 is detached and the foot 136 then swung down and locked, and steps 140, 141 hinged to the bar and plate 129, respectively, are swung out and a jack 142 applied between them, Fig. 17. Operation of the jack raises the breaker on the bar to the operative position whereupon pin 145 is inserted in the aligned holes 143, 144 to retain the breaker. In this position, the pin 145 is covered by a lever 146 in the path of the trip lever 105, Fig. 12, to prevent removal of the breaker until it has been tripped open. When the breaker has been removed, its cover can be lifted by means of the bar 131 and jack 142 in conjunction with a portable hospital bay. The cover is raised in two stages, the first utilizing a platform on the bay as the lower abutment for the jack, and the second utilizing step 140, Fig. 19 (not shown). Automatic circuit-breakers.-The automatic trip is shown in Figs. 12, 13 in the set and tripped positions respectively. The shaft 85 carries a crank arm 90 having a roller 91 which is normally restrained against clockwise movement under spring-action 88 by a roller 92 on a lever 93 which is pivoted to the end of an arm 94 on a shaft 95 concentric with 85. Lever 93. is also linked at 97 to a bell-crank 98 pivoted at 99 and normally retained by the spindle 100 having a flat surface 101. Also pivoted to 94 is a latch arm 106 engaging a fixed plate 107 and connected by spring 109 to an arm 110 on crank 94. When the spindle 100 is rotated to the Fig. 13 position by raising the rod 103 either by solenoid 104 or the hand trip 105, the flat surface 101 releases crank 98 and hence lever 93, so allowing roller 91 to ride over roller 92 and open the breaker. During this movement of lever 93, a stud 111 thereon engages an arm 112 on catch 106 and so frees it from plate 107. Clockwise rotation of shaft 95 by the handle 113 into the open position causes the roller 92 to ride under roller 91 and reverse rotation of 95 closes the breaker. After tripping, a projection 90<a> on lever 90 engages pin 111 to retain link 93 in tripped position during the rotation of 94, 95 to open position, so preventing the toggle 97, 98 from straightening and resetting the lever 93 until roller 92 is in position behind roller 91. An arrangement for preventing removal of the handle 113 from the shaft 95 excepting in the extreme positions is also described, Figs. 15, 16 (not shown).