Patent GB-547384-A (GB)
Title: Improvements in electrical systems of remote indication
IPC: H02J13/00
Filed: 1941-10-29
Abstract: 547,384. Selective signalling. GENERAL ELECTRIC CO., Ltd., and FIELD, R. W. G. Oct. 29, 1941, No. 13901. [Class 40 (i)] [Also in Group XXXIX] In a system for signalling the position of power sub-station circuit-breakers &c. utilizing the ordinary telephone exchange net-works, supervisory signals are sent from a substation in response to a call set up thereto, and the signals cause the final selector to reverse the current in the calling loop to operate a polarized relay which, in conjunction with a step-by-step switch and relays controls indicating lamps. The substation Fig. 2, has telephone equipment 12 and supervisory equipment arranged for selective leg ringing with two appearances (reversed feed) in the final selector bank as in Specification 532,514. At the control station Fig. 1, the supervisory equipment including dial DL is connected up by key KA which disconnects the normal telephone equipment 16. When the supervisory call has been set up the substation is rung over the + wire and transformer IT whereupon LS pulls up if switch SS is normal. Magnet SS is connected to 2 p.p.s. conductor 14 and relay HB pulls up over bank SS2 to complete the loop and trip the ringing, current reversal in the calling loop causing the operation of polarized relay LR and the holding of LG originally operated over another winding. At the calling station B, BA and C pull up. Relay B has a release period of over ¢ second and the combined release periods of the three relays is less than 1¢ seconds. Relay LR lights lamp LB to indicate that the call has been successful. When the substation switch SS passes over contacts 6-9, HB relapses and calling loop current is reversed for a period sufficient for LR and B, BA, C to release in succession. The release of LR and B drives back-stroke switch CS1 off normal and the relapse of C causes it to step in a self-interrupting circuit to contact 6. The substation switch SS now steps over a set of three contacts 9-11 of which 9 and 11 are permanently connected to battery and 10 is connected to battery or disconnected dependent on the condition of circuit breaker CCA. If 10 is connected to battery (as shown) HB is steadily operated over these contacts to operate LR, B, BA, C at the calling station and when it falls back (contacts 12-14) the said relays relapse in turn to cause, in succession, the stepping of CS to contact 7, the operation of coil PXA of a twoposition relay to light lamp LCA, and the selfstepping of switch CS to contact 11. If contact 10 of SS is disconnected, the relapse of HB and LR for a period of less than ¢ second causes CS to take 1 step to contact 7 but since B, BA and C, do not release, nothing further happens until HB is released for a long period during the passage of SS over contacts 12-14 when the previously described operations occur except that CS has now stepped to contact 8 and coil PYA is operated to light lamp LDA. Further contact breakers are dealt with in similar manner and DR operates over the last contacts of SS to disconnect the pulse conductor. The last relapse of HB brings about the release of LR, B, BA, C at the control station whereupon CS steps to last contacts and lights lamp LA. On restoration of key KA, relays HO and LG restore and CS goes to normal ; the final selector releases whereupon LA, LS fall back and SS goes to normal. The two-position relays may be as described in Specification 465,300, [Group XXXVII]. Specification 465,356 also is referred to.