Patent GB-244512-A (GB)
Title: Improvements relating to metering in automatic telephone systems
IPC: H04Q3/00
Filed: 1924-09-15
Abstract: 244,512. Siemens Bros. & Co., Ltd., and Berry, J. Sept. 15, 1924. Automatic exchange metering systems. - In systems in which a variable number of impulses is supplied to a subscribers meter by continuously operating cam interrupters the apparatus for starting a cycle of metering impulses is associated with the first selector, and is so arranged that a metering cycle is not started unless the answering condition of the called line persists for a definite time. The proper interrupter is selected by a switch responsive to impulses, e.g. a vertical wiper of the first selector or of a subsequent selector associated over an extra bank and wiper with the first selector. Where however the selectors concerned are in different offices, the trunks taken into use by the first selector are provided with auxiliary switches which respond to the second or to the second and third digits to select an appropriate interrupter. The arrangements for starting a metering cycle are similar to those described in Specification 200,928 for sending a single impulse. Systems are described in which all calls are metered in accordance with the first digit, all calls are metered in accordance with the first two digits, some calls metered in accordance with the first digit and others in accordance with the first two or three digits. Operation of first selector, Fig. 1. Line relay A is first energized over the incoming C-wire and its winding 3, and is followed by release relay V and dialling relay D. Dialling tone is sent from DS and relav A which is now controlled by the loop, repeats the digit to vertical magnet VM. Vertical springs k1 - - k3 change over and at the end of the first impulse relay L pulls up and locks itself. At the end of the digit relay D falls back and the rotary magnet RM is operated in the circuit v2, k2, d2, t5 until the test relay T pulls up. Subsequent digits are repeated by contact a3. Metering all calls in accordance with first digit, Fig. 1. The vertical wiper P‹ selects one of a number of interrupters controlled by cams 12 - - 14 on the same shaft as the cams 10, 11 of the timing arrangement. When the called party replies, relays Y, H, pull up, and relay L falls back and circuits are made by the interrupters 10, 11 for relays S, Z, which operate as described in Specification 200,928 to complete the metering circuit after a prescribed. delay for a definite time over wiper P<0> and the selected interrupter. Preventing metering of calls to a manual board. Relay H pulls up without relay Y and metering therefore does not take place. Release relay V is held independently of the line relay over h1, l4. Metering all calls in accordance with the first two digits, Fig. 2. All outgoing trunks are provided with the apparatus shown to the right of the Figure. When the trunk is seized, relays N, A, A, pull up over the c and b-wires, followed by relay DD. Impulses from the first selector are repeated by relay AA over the trunk and to the stepping magnet RM<1> of the simple switch A<1> - - D'. At the end of the train, owing to the opening of the various normal circuits, relay DD falls back and cuts off relay AA which cannot be energized again. When the called party replies, relays S, Z, operate as described in connection with Fig. 1, to complete the metering circuit which in this case goes over a fourth wiper D<0> of the selector and the wiper D' of the simple switch. Metering some calls in accordance with first digit, Fig. 3. This selector is operated in the same way as the selector shown in Fig. 1 except that the test relay T grounds the c-wiper over a contact of relay S instead of direct. The metering arrangements are similar to those shown in Fig. 1, but only some of the vertical terminals are connected to the interrupters 12 - - 14, and the metering impulses instead of being sent direct, are repeated by a relay M. Interrupter 10 on closing after the energization of relay Y, energizes relay S (1) and relay S locks over its winding 2 to the contact Z3, removes direct ground from the c-wire (which remains grounded over M (1)) and connects it to relay M (2). The current through M (1) is not sufficient to energize the relay. Subsequently, interrupter 11 energizes relay Z, and the selected interrupter impulses relay M (2), metering impulses being sent over m1, z1. When contact 11 opens, relay S falls back and relay Z remains locked up as in Fig. 1. Metering some calls in accordance with first two digits, Fig. 4. The trunks in some of the levels of the first selector, Fig. 3, are provided with simple switches A<1> - - D<1>, Fig. 4. The trunk is tested over wiper E<1>, and when the talking wires are switched through, relays AA, DD, MA pull up in succession. The second digit is repeated by relay AA over the trunk and to the stepping magnet RM<1>. At the first step off normal relay N which has hitherto been short-circuited, pulls up over the c-wire and at the end of the train relay DD falls back and cuts off relay AA. When relay S, Fig. 3, pulls up to indicate the metering-operation the direct ground on the c-wire is replaced by ground over M (1) and relay ZZ being no longer short-circuited, pulls up over n<2>, ZZ (1), E<1>, N, and locks up over both its windings in series. When relay Z, Fig. 3, pulls up, the relay M receives impulses from the selected interrupter over D' zz2, ma2, t4, M (1) and repeats them to the subscriber's meter. During metering, relay N is held up over its winding 2 and interrupter 20. At the end of the cycle the cam 20 unlocks relay MA. Metering some calls in accordance with the first three digits, Fig. 5. The trunks on certain levels are associated with Strowger switches, Fig. 5, with controlling circuits similar to those of a connector. The trunk is tested over relay N (1). Relays N, AA, DD pull up and the second digit is repeated over the trunk and over aa2, dd4 to the vertical magnet VM<1>. Owing to the change over of vertical springs k1 - - k4, relay DD falls back at the end of the digit and energizes relay G which re-enegizes relay DD, and the third digit is received by the rotary magnet RM<1>. Rotary springs w1, w2, change over and at the end of the digit, relays DD, G fall back in succession. Relay MA which was first energized by relay G is held locked over ma3, zz3. As in the arrangement shown in Fig. 4, the energization of relay S, allows relay ZZ to pull up, the control of relay MA is given to. the interrupter 20, and subsequently metering impulses over wiper D<1> control the relay M, Fig. 3. Relay N is held up during metering over its winding 3. Alarm arrangements. As shown in Fig. 1, the lamp PL which is connected in a delayed alarm circuit, is lit by the release relay V when the selector is taken into use and is extinguished by relay L which pulls, up at the end of the first impulse. The same lamp is lit if the selector in hunting reaches 11th terminals. According to the Provisional Specification, the system shown in Fig. 2 may be used for metering in accordance with either the first digit or the first two digits. In this case the terminals of the extra bank in the levels for which metering is to be in accordance with the first digit only, are multipled together and connected to the appropriate interrupters direct.