Patent GB-157324-A (GB)
Abstract: 157,324. Siemens & Halske Akt.-Ges. Dec. 8, 1913, [Convention date]. Automatic exchange systems; metering systems.-In systems in which the calling subscriber's meter is operated at the termination of a conversation, and in which metering and release are controlled entirely over the a and b wires of the selector trunks, the release of the selectors is initiated from a single point in the selector chain after metering has been completed. Three arrangements are described, in all of which provision is made for operating, the subscriber's meter a variable number of times. First arrangement, Figs. 1 and 2. In these Figures, a connection is represented as extending through a preliminary selector VW and first selector IGW and over a two-wire trunk, having a relay repeater set R at its outgoing end, to a second selector IIGW and final selector LW. During conversation the following relays are energized :-T10, CI, A and F, Fig. 1, and CII, P314, P418, U, A410 and B, Fig. 2. When the calling subscriber hangs up his receiver, the deenergization of relay A, Fig. 1, energizes relay S and grounds the a wire to energize relay A310, Fig. 2, which energizes the magnet Z320 and closes a circuit over the b wire through relay Z112, Fig. 1, winding 309 of relay CII and relay A410. The magnet Z320 operates a toothed. wheel so as to open the circuit of relay Z112 a certain number of times at contact 321, and finally leaves it open. At each energization of the relay Z112 a resistance W103 is short-circuited to energize the meter Z3. When the relay S was energized it short-circuited the relay CI, and when the relay A310 was energized it short-circuited the winding 308 of relay CII. The relays CI, CII were thus rendered sluggish, and during the passage of metering impulses they remained energized, the winding 309 of the relay CII being in circuit with the metering relay Z112 while the short-circuit round the relay CI was opened every time the relay Z112 was energized. At the termination of the metering impulses the relay Z112 remains open-circuited and the relays CI, CII relapse and energize the release magnets M130, M324. The relay CII also de-energizes relav P418. so that as soon as the called subscriber hangs up his receiver the de-energization of relay A410 completes the circuit of the releasemagnet M402. If the called subscriber is the first to disconnect himself, the de-energization of relay B grounds the a wire so as to energizerelays S, A310. Metering then proceeds as already described and the selectors IIGW, LW are released, but the selector IGW is not released until the calling subscriber disconnects himself. Second arrangement Figs. 3 and 4. In these Figures a connection is represented as extending through a call-finder AS, over a two-wire trunk to a first selector IGW, and over a second two-wire trunk to a second selector IIGW and final selector LW. During conversation the following relays are energized :-T, A1, B1, E1, F1, C1, Fig. 3, and FII, PII, Cm, U, Y, Fig. 4. When the calling subscriber hangs up his receiver, the relays A1, B1, E1 in his line circuit relapse, but the relay Fl is rendered sluggish by the parallel resistance 204 and holds up its armature, and a circuit is immediately closed through the relays F1, A1, by the de-energization of the relay T, which is unlocked by the de-energization of relay E1. The relay B1 grounds the b wire to energize relays Z1, Fig. 3, and ZIII, Fig. 4; this ground connection is immediately opened again by the consequential energization of relay S, but relay ZIII locks itself up, connects the b wire to ground through a switch 611, and operates this switch to interrupt the ground connection a certain number of times. Impulses are thus transmitted to the metering relav Z1, which repeats them over the incoming b wire to the meter Z. The meter is constructed to register only at every alternate step (so that the first impulse is ineffective), and is of high resistance, so that relay E1 does not energize in series with it. When relay B1 became de-energized, it opened the circuit of relay C', but this relay is of the sluggish type and is kept energized by impulses over contact 306 of the metering relav Z1. At the termination. of the metering impulses, the circuit of relay Z1 remains open at the switch 611 and relay CI relapses, energizing the release magnet M1, and grounding the outgoing a wire to energize relay AII, which energizes the release magnet MII and unlocks relay CIII, which prepares the circuit of release magnet MIII, which is energized by the relapse of relay Y when the called subscriber disconnects himself. The release magnet MI of the first selector is of sluggish type, and controls contacts for disconnecting the a wiper (to prevent interfering ground connections to the terminals of the trunks) and for opening the circuit of relay F1. The relapse of relay F1 closes a contact 215 in the starting-circuit of the finder AS, so as to render it available for other service. If the called subscriber is the first to disconnect himself, the de-energization of relay Y grounds the b wire to energize relays Z1, ZIII, and metering proceeds as already described. Third arrangement, Fig. 5. This Figure represents a modification of the circuits shown in Fig. 3, the connection being made over a singlewire trunk as far as the first selector. When the calling subscriber disconnects himself, the relays B1, E relapse and relay E opens the circuits of relays T, F. The relay F, however, is of sluggish type and holds up its armature. The relay B1 energizes relay Z1, which then receives metering impulses as described in the previous paragraph. The relay Z1 repeats these impulses to the meter Z through the relay E, which keeps the relay F er ergized. At the termination of the metering impulses relay F relapses and closes the contact 215 to render the finder AS available for other service. Preventing metering of unsuccessful calls. It will be observed that the metering control circuts include contacts of relays U, Figs. 2 and 4. These relays are not energized unless the called subscriber has answered the call. The invention is stated to be applicable to systems in which, on the termination of a conversation, connection is automatically made to an operator, who ascertains the numbers of the subscribers and enters a record of the call.