GB467867A - Improvements in or relating to telephone and like signalling systems - Google Patents

Abstract

467,867. Electromagnetic relays. STANDARD TELEPHONES & CABLES, Ltd. April 27, 1936, No. 11933. Convention date, April 27, 1935. [Class 38 (v)] [Also in Group XXXIX] A relay responsive to impulses over lines of widely different characteristics has one winding connected to the line and a second winding in series with a condenser which assists the operation and release of the relay. In Fig. 1, the impulse relay 36 is such that it releases readily and is in series with an auxiliary relay 33 which operates readily. Both relays are provided with biassing windings. When relay 33 responds to the closure of the loop, the discharge of the condenser 35 assists the operation of relay 36, and when the loop is opened, the discharge in the reverse direction assists the release of both relays. In Fig. 2, the impulse relay 13 controls a repeating relay 21. The operation of relay 13 is aided by the discharge of the condenser 20 as soon as its back contact is opened, and its release is aided by the discharge in the reverse direction as soon as its front contact is opened. The charging circuits ensure that relay 13 remains operated and released for certain minimum periods. The resistances connected to the biassing winding are such that the biassing current is a minimum when the relay is unoperated and a maximum when it is operated. The Specification as open to inspection under Sect. 91 comprises other arrangements. In Fig. 1 (Cancelled), a readily-operated auxiliary relay 23 completes the charging circuit of the condenser 25 which assists the operation of the impulse relay 26, the latter being readily releasable. In Fig. 5 (Cancelled), the condenser 521 controlling the impulse relay 56 is included in the anode circuit of a gas-discharge tube 522 of which the grid circuit is coupled to the line by a transformer 53. At each opening of the line loop, the positive potential on the grid ionizes the tube 522 and the condenser 521, which is normally charged, discharges through relay 56 and holds it momentarily. The condenser then begins to recharge and aids the release of relay 56. The tube becomes non- conducting on account of the shunting effect of the charging condenser. This arrangement, together with a filter circuit 54, 55 obviates false operation by surges. A modification of this arrangement is also described. A further arrangement is similar to that of Fig. 2 with the difference that only the release of the impulse relay is aided. This subject-matter does not appear in the Specification as accepted.