GB261128A - Improvements relating to automatic and semi-automatic telephone systems - Google Patents

Abstract

261,128. Siemens Bros. & Co., Ltd., and Patterson, W. G. Aug. 27, 1925. Automatic exchange systems; metering.-In a system employing switches of the Strowger type and having feed current supplied from the connector, the incoming test wire of an idle switch is connected to battery over a shaft contact, and is grounded by the release relay upon seizure of the switch to hold the preceding switch or switches. The invention may also be applied to the repeater at the outgoing end of a two-wire trunk, and to the 'A' digit switch in a system employing register-controllers. Line switch, Fig. 1. When an idle link is reached, switching relay T is energized over winding 1 by battery over the test terminal, and looks over both windings to ground at contact r1, which is replaced by ground fed back over the test terminal before line relay R relapses. Group selector, Fig. 2, with continuous test wire. The rotary magnet RM operates under control of its contact rm until an idle link is reached, whereupon test and switching relay G is energized by battery over the test terminal, and locks over off-normal contact k1 to ground at contact bl, which is replaced by ground fed back over the test terminal, before release, relay B relapses. The incoming test wire is connected through to the test wiper at contact q1. If no idle link is found, the switch moves into the 11th position, and relay G energizes over contacts s2, connecting up the busy signal, and a statistical meter is operated over contacts s1. Connector, Fig. 3. Release relay B grounds the test wire at contact b3. Change-over relay G falls back slowly when all the impulses have been received, and connects up relay S, which supplies ringing current to the called line or busy tone to the calling line according as test relay, H is energized or not. Ring cut-off relay F upon energization applies booster metering battery to the test wire for an interval dependent on the release time of relay S. Group selector with discontinuous test wire. Fig. 2 is modified by providing a separate contact of relay B for operating relay G, and the incoming test wire is grounded over a front contact of relay G when the succeeding switch is seized. In this case metering is preferably effected by the reversal of line current at the connector.