Patent GB-729218-A (GB)
Title: Improvements in electromagnetic contactors
Inventor: WALTON JAMES RIGNELL
IPC: H02B11/00
Filed: 1952-06-11
Abstract: 729,218. Electromagnetic switches; switchgear structures; switch cases; controllers. ELECTRICAL APPARATUS CO., Ltd. June 10, 1953 [June 11, 1952], No. 14651/52. Classes 38 (3) and 38 (5). An electromagnetic contactor which may be also hand operated to the open position has readily disengageable (e.g. plug and socket) connection with the supply mains so that it may be withdrawn as a unit to break the connection and thereby be isolated. As shown, the contactor comprises an insulating base 61 pivotally supporting a contact-carrying shaft 63, the movable contacts 67 engaging fixed contacts 11 when an armature 65 on the shaft is attracted by a magnet 9. The contacts 11 are connected through bracket 12 to socket contacts 15 mounted on the back of the base 61 which engage plug contacts 16 connected to the load. The contacts 67 are connected to a further set of contacts 15 through flexible connections 13, fuses 40 and stems 54, these contacts 15 engage a further set of contacts 16 connected to the supply mains. The base 61 is carried by a metal frame 17 having a pair of slides 18 which, through balls 19, run in slides 20 fixed in an outer casing 21. Thus, the frame 17 may be withdrawn from the casing 21 to separate the contacts 15, 16 and isolate the contactor. A cover 23 is fixed to the frame 17 by nuts 52 which are accessible only when the frame is withdrawn. The cover 23 carries a shaft 22 operable by a handle 24, and on the inside of the cover (Fig. 3) the shaft carries a lever 25 pivotally connected to rods 26, 27. Rod 26 is pivoted at 28 to a lever 29 pivoted to the cover at 30. When the handle 24 is moved to the "off" or "withdraw" position, a face 32 on the lever 29 can press a lever 68 on the shaft 63 downwards to open the contacts 67 for the purpose described below. The rod 27 is pivoted at 34 to a lever 35 pivoted to the cover at 36, the lever 35 operating a double pole auxiliary switch 53 mounted on the base 61 and connected in the circuit of the contactor operating coil 10. The arrangement is such that when the handle 24 is moved to the "off" or "withdraw" position the switch 53 is opened to open the contacts 67 before they are operated through the lever 68, the latter merely providing a safeguard. The ends of the rods 26, 27 engage beneath flanges 56 on the casing 21 and prevent withdrawal of the frame 17 except when the handle 24 has been rotated to the "withdrawal" position. The base 61 also carries two fuses 38 in the circuit of coil 10, "start" and "stop" switches 59, 60, a timing relay 39, and an overload and singlephasing preventor 41 energized from transformers 55 surrounding the stems 54. Auxiliary switches 1 ... 8 comprising contacts on the frame 17 which engage contacts in the casing 21 when the frame 17 is inserted may be provided to serve a remote push button station, interlocks, and a contactor in the rotor circuit of a motor whose stator is controlled by the contacts 11, 67, (Fig. 9). In the instance where the auxiliary circuits are energized from an external source of supply other than the main supply to the contacts 67 shutter means are provided in the casing 21 which cover the auxiliary contacts fixed within the casing when the frame 17 is withdrawn, the shutter being raised by insertion of the frame to permit the auxiliary contacts carried thereby to engage the complementary contacts in the casing. The construction of these auxiliary switches and the shutter means is illustrated in Figs. 5-7 (not shown).