Patent GB-191119230-A (GB)
Title: Improved Circuit Arrangements for Automatic Telephone Systems.
Filed: 1911-08-28
Abstract: 19,230. Siemens & Halske Akt.-Ges. Aug. 27, 1910, [Convention date]. Void. [Published under Section 91 of the Act.] [Application for Patent of Addition to 19,187/11.] Automatic exchange systems; metering systems. - In systems in which repeating relay sets are arranged between the preliminary selectors and the group selectors and in which the release of a connexion takes place in order from the first selector to the second and so on, a relay inserted in the incoming end of the test lead and energized throughout a connexion, closes the circuit of the release magnet when the test lead is opened at the preceding selector. The invention is described as applied to a system using no side - switches, and in which the subscriber's impulse-sender earths the b-line while it interrupts the a-line. Preliminary selector. When a subscriber removes his receiver, his line relay R completes the circuit of the actuating-magnet D, which rotates the selector until its wipers find an idle group selector IGW, whereupon the cut - off relay T is energized by current which flows over its high and low resistance windings, lead c<0>, contacts 14, 15, relay C', Fig. 2, and selector contact k<1>1. The relay T cuts off the line relay R and magnet D and short-circuits its highresistance winding over contact 16, thus marking the line as engaged. The current over the test lead is too weak to actuate the meter Z at this stage. Relay repeater. The calling line is thus supplied with current over the relays A, Band a differential relay X. The relay B closes at 22 the circuit of a self-locking sluggish relay V, which opens the contact 14, thus introducing into the test-lead circuit the low-resistance winding of a relay C, whereby the high-resistance winding 26 is brought into parallel with the relay C', Fig. 2. The relay V remains energized until the metering relay Zr is energized upon the response of the called subscriber. First selector. When the calling subscriber turns his impulse-sender, his b-line is earthed, causing the excitation of the differential relay X, which closes a fresh circuit for the relays B, X. The subsequent interruptions of the a-line are repeated by the relay A over the contacts 33, 34 and lead a<1> to the relay A<1> and vertical magnet H'. During this time, the relay X connects the battery over a contact 31 to the lead b<1>, energizing the relay B<1>, but when the impulse-sender returns to zero, the relay X is de-energized, and the relay B<1> closes at 41 the circuit of the rotary magnet D<1>, which rotates the selector until its wipers engage the terminals of an idle second selector. The test relay P<1> then energizes in series with a relay C<2>, cuts off the rotary magnet, connects the leads a<1>, b<1> to the leads a<2>, b<2>, and short-circuits its high-resistance winding so as to mark the lead c<2> as engaged. The relays C, C<1>, C<2>, P<1> remain energized throughout the connexion. Second and third selectors. The second and third sets of impulses are similarly repeated by the relay A to the relays A<2>, A<3> of the second and third selectors, which operate in the same manner as the first selector, except that a modified connexion for the release magnet M<3> is shown in the third selector. The relay P<2> energizes in series with the relay C' and the release magnet, but the latter is not energized at this stage. Connector. The relay C<4>, Fig. 3, which energizes in series with the relay P<3>, Fig. 2, closes at 71 the circuit of a relay E over the contacts 71, 70, k<4>2, and the relay E closes contact 72 so as to maintain its circuit when the contact k<4>2 is opened by the vertical movement of the connector. The relay E earths the relay A<4> at 73, so that the fourth set of impulses is repeated by the relays A and A<4> to the vertical magnet H<4>. During this time the relay B<4> is energized by the relay X, Fig. 1, but when the impulse-sender returns to zero, the relay B<4> closes at 77 the circuit of a self-locking relay F, which substitutes the rotary magnet D<4> for the magnet H<4>. While the last set of impulses is being repeated by the relays A, A<4> to the rotary magnet, the relay B<4> closes at 84 the circuit of a relay G in preparation for the busy test. Busy test. The relays E, F, G being all energized at this stage, when the relay B<4> deenergizes, the test relay P<4> is earthed over contacts 85, 86, and if the wanted line is engaged, the relay P<4> is not energized, but the opening of the contact 84 of the relay B<4> de-energizes the relay G, which in turn opens the circuit of the relays E, F. The relay G also connects a busy transformer 107 over contacts 108, 109 and condenser 110 to the calling line. The connexion is released when the subscriber hangs up, as described later. Supply of ringing-current. If the wanted line is free, the relay P<4> is energized and closes a fresh circuit for the relay G, so that this relay is not de-energized. The relay E is, however, de-energized by the opening of the contact 95, and opens the circuit of the slow-release relay F. During the de-energizing of this relay the ringing-relay L is energized over the contacts 96, 97, 98, and connects the generator RQ to the called line. After the relay F is deenergized, the relay L is periodically energized over an interrupter 102. When the called subscriber removes his receiver, the supervisory relay Y connects the leads a<4>, b<4> to the called line, and opens a contact 94 in the circuit of the relay G, thereby cutting off the ringing- current. A disengaged signal is also sent to the calling subscriber from the transformer 118 over the condenser 110. Metering calls. The excitation of the relay Y connects the battery to the speaking lead b<4>, thereby energizing the metering - relay Zr, Fig. 1, which earths the test lead c<0> over a small resistance 105, thus increasing the current in the lead sufficiently to actuate the meter Z. The relay Zr also opens the circuit of the slowrelease relay V, which in turn disconnects the relay Zr from earth, and closes contact 14. Release. When the calling subscriber replaces his receiver, the relay B opens at 21 the circuit over the test lead c<0>, c<1>, thereby de-energizing the relay C<1>. The current flowing over the lead c‹ and the high-resistance winding of the relay C is so weakened that the relay T releases its armature, thus breaking the test circuit. The preliminary selector is returned to normal in known manner. The relay C<1>, Fig. 2, closes the circuit of the release magnet M<1> and breaks the circuit through the relays P<1>, C<2>. The relays C<2>, C<3> in turn energize the release magnets M<2>, M<3> and open the circuits of the relays P<2>, C<3>, and P<3>, C<4>. The selectors are thus released, but the release of the connector is delayed until the called subscriber hangs up, the circuit of the release magnet M<4> including contacts 114, 115 controlled by the relays C<4>, Y, respectively. If the called subscriber hangs up first, the connector is not released until the calling subscriber hangs up, but he would be rendered idle to other calls since the relay Y opens at 116 the circuit of the relay P<4> and cut-off relay T<1>.