Patent GB-417591-A (GB)
Title: Improvements in or relating to systems and apparatus for automatically controlling acircuit breaker or the like and adapted to operate on the occurrence of an abnormal condition in an electrical circuit
IPC: H01H29/10
Filed: 1933-03-02
Abstract: 417,591. Protective cut-out systems. I.T.E. CIRCUIT BREAKER CO., 19th Street, Philadelphia, U.S.A.-(Assignees of Scott, W. M., Healis, G. A., and Graves, H. C.) March 2, 1933, Nos. 6385 and 6386. Convention dates, March 11, 1932 and April 15, 1932. [Class 38 (v).] Automatic circuitbreakers ; electromagnetic switches ; mercury switches ; retarding devices.- An electrical control system comprises a circuitbreaker or the like adapted to operate on the occurrence of an abnormal condition in its associated circuit and controlling means for the breaker. A switch device which is movable by, or in accordance with, the movements of the breaker comprises a fluid reservoir and contact elements for governing the energization of said controlling means, the switch device being so arranged that the contact elements are only rendered effective by flow of fluid from the reservoir after a predetermined time interval on movement of the switch devices. Opening of the breaker contact 28 by trip coil 45 causes a switch 1 to be rotated clockwise through 90‹ by means of link 44 to energize the closing coil 29 and, through lever 43 and link 42 to reclose the breaker, whereupon switch 1 is returned to the position shown. Figs. 8, 9 show the inoperative and operative positions, respectively, of 1 and Fig. 2 certain of its constructional details. The casing is in two insulating parts 1<a>, 1<b> separated by a part 1<c>, and contains a series of chambers and passages, into which mercury or other conductive liquid can be introduced by removing a plug 26 so as to flow down passage 5 into a reservoir 6. Leading from the latter into a contact chamber 13 are apertures 9, 10, 11, adjustable from outside by screw stems, and passages 8, 12. The normal level is shown dotted in Fig. 9. When the breaker opens, the parts assume the position of Fig. 9 and mercury flows into chamber 13 until it covers the contacts 15<a>, 15b in the circuit of 29 so that the latter closes the breaker and restores 1 to the position of Fig. 8. The mercury in 13 flows down 16 into chamber 2 and, provided the breaker remains closed, slowly trickles back into 6 by way of passage 4. If the breaker opens after its first reclosure, mercury again flows from 6 into 13, but at a reduced rate owing to the smaller head and to the consequent fact of passage 9 being above the new liquid level. The third reclosure is still more retarded as only the passage 11 is available, and if the breaker again opens, no more mercury is available, and the switch must be reset by opening valve 25 to allow liquid to flow from 2 through passage 5 into the reservoir 6. Normally, a passage 20, chamber 19, and passage 18 allow air circulation, but after a third unsuccessful reclosure, the level in 2 rises above the entrance 21 to passage 20 and allows mercury to enter chamber 19 to bridge alarm contacts 40<a>, 40b. Ledges 17, 14 prevent mercury returning from 2 or 16 into 13. Fig. 8 shows a control system for the breaker 28 and closing winding 29, involving a hand switch 50 which can be placed either on contact 51 for automatic operation, or in a mid position for non-automatic operation, or on contact 52 for distant control by button 36. When the breaker is open and 36 is closed, a circuit is made from busbar 31 over 50, 52, 36, windings 35, 34 in parallel (the latter winding over closed pallet switch 37) to busbar 32. Windings 34, 35 are so proportioned that 34 predominates, closes contacts 33, and energizes 29 to close the breaker. If 36 is still held closed, and as 37 has opened, 35 attracts armature 30 against its pole, from which position the combined action of a centralizing spring (not shown) and of the winding 34, should it have been again energized by subsequent reopening of the breaker, will be ineffective to move it ; to allow it to move, it is necessary to release 36 and allow the centralizing spring to return 30 to its mid position. Manual tripping is by means of a button 38 and coil 45<1>. With switch 50 on contact 51, the coil 29 is controlled by the magnet R under control of contacts 15a, 15b instead of button 36. The lamps 53-55 denote closed; open, locked open, respectively the latter circuit being over contacts 51, 40<a>, 40<b>, 56. Fig. 11 shows a modified liquid switch comprising a container pivoted at 74 and having chambers 61, 63, 66 intercommunicating by passages formed as bores in adjustable bolts 68, 71, access to the bores being had by slitting the shank at 62 over a portion of its length. In the open position shown, mercury passes from 61 to 63 by way of 62 and a small orifice at the foot thereof, at a rate depending on the position of the bolt 68 and therefore on the head of mercury above the orifice, and after a given time to spill over into a space 64<a>, whereby contact 64 therein is rapidly connected to 65 to energize the closing coil. The container is rotated counterclockwise to discharge the mercury into 66 so that it trickles back into 61 by way of 67. As before, the number and rate of reclosures depend on the head of mercury in 61. In another form, a separate container is provided for each reclosing operation, Fig. 13 (not shown), all being mounted on a common shaft and each having its own timing features and being rendered ineffective once it has operated. The use of such a modification is illustrated in Fig. 17 (not shown) in combination with a float-switch for tripping the breaker when the liquid level in a tank rises to a given value, so cutting out the driving motor of the pump. If the pump motor is overloaded or stalled, due to an obstruction in the fluid supply pipe, the breaker is tripped by its overload coil and reclosed successively. The control switch 1 may be rotated by an electromagnet energized in accordance with the movement of the breaker, Figs. 18, 19 (not shown).