Patent GB-191401157-A (GB)
Title: Improvements in Telephone Systems.
Filed: 1914-01-15
Granted: 1915-07-29
Abstract: 1157. Siemens & Halske Akt.-Ges., Laidlaw, E. A., and Pettigrew, T. Jan. 15. [Addition to 18,498/12.] Automatic and semi-automatic exchange systems.- Relates to systems of the kind described in the parent Specification and in Specification 3431/13, in which the same connectors are used for ordinary and preferred calls. According to the present invention the only additional apparatus provided at the connectors for setting up the preferred calls consists of one or more relays. Three systems are described, in the first of which the operator receives different busy signals according as the wanted subscriber is engaged in a local or preferred call, and can release the selectors used in a local call in favour of the preferred call. In the second system, the operator does not receive a signal to inform her whether the wanted subscriber is engaged in an ordinary or in a preferred call, but is connected to his line in either case, and informs him that he is wanted for a trunk call. In the third system, the operator is informed if the wanted subscriber is engaged, but not whether in an ordinary or preferred call. To obtain this information, the operator again sets up the connexion over a special connector. First system, Figs. 2, 3 and 4. Establishment of ordinary call by subscriber ; first selector. A calling line is connected by preliminary selectors, described in Specification 26,905/13, to an idle group selector IGW, thus energizing the relays A1, B1 over the calling line. The relay A1 energizes the slow-release relay V1, which remains energized throughout the connexion. The first set of impulses is repeated by the relay A, to the vertical magnet H1 in the usual way, and as soon as these cease, the slow, release relay V2 energizes the rotary magnet D1 over contacts 22, 17, 5, k3- When an idle second selector is found, the test relay C, is energized over contact 16, winding 1, lead C1, and in parallel over relays B, C of the second selector. The relay C1 (1) directly grounds the test lead C1 over contacts 5, k3, (2) locks up in a circuit from earth over contacts i1, 4, winding 2, resistance w1, and the test lead c, and (3) connects the calling line through to the second selector. Second selector, Fig. 2. When the second selector is seized, the relays B, C are energized, relay C closing contact 25 so as to be independent of contact k5 and closing contact 26 so as to make relay B slow to release by short-circuiting . its winding 2. The second series of impulses is repeated by relay A1 over contacts 19, 10, 2, 24 to the relay A, which repeats them to the vertical magnet H. After the first vertical movement, the circuit of relay B is opened at contact k6 ; but as it is made slow to release by the short-circuiting of its winding 2, it is maintained energized by the intermittent closing of contact a3. At the end of the impulses, relay B closes over contacts b1, k7, 27, a2, the circuit of the rotary magnet D, which rotates the selector. After the first rotary step, the contact i is opened, but the circuit of the relay C is maintained over contacts 25, b5, and lead c1, so that the winding 2 of relay B is connected to the test wiper c2. When an idle connector is found, the relay B is energized, therehy (1) disconnecting the rotary magnet D, (2) connecting the calling line through to the connector at contacts b2, b3, (3) directly earthing the test lead at contact b4, (4) permanently disconnecting the relay C at contact b5, and (5) locking up over its winding 1, front contact b5, contact and test lead c1. Connector, Fig. 3. When the connector is seized, the winding 1 of relay C3, Fig. 3, energizes in series with the winding 2 of a slow-release relay Q. The relay C3 locks up over its contact 28, and by closing contact 35 energizes a slow-release relay Vs, which in turn energizes relay G over contact 37. The relays C3, V3, Q, G are thus energized directly the connector is seized. The tens impulses are repeated by the relay A1, Fig. 2, over the lead a and contact 40, Fig. 3, to the winding 1 of relay A3, which repeats them over contacts 41, 47 to the vertical magnet H3. After the first vertical movement, the circuit of the slow-release relay Q is opened at contact k8, but is maintained during the transmission of the tens impulses over contacts 29, q4, 44. As soon as the impulses cease, relay Q is de-energized, and substitutes the rotary magnet D3 for the vertical magnet, so that the units impulses are repeated to the magnet D3. Busy test and signal in normal call. At the first rotary movement of the selector, the contact i3 opens the circuit of the slow-release relay V3 ; but this is kept energized during the transmission of the units impulses over contacts 48, 41. At the end of these impulses, relay V3 de-energizes and closes the circuit of the test relay P over contact 41 and contact l1 of the ringing-relay L, which was energized over contacts q5, g1, i3, 35 on the first rotary movement of the selector. If the wanted line is engaged, the relay P is not energized, and a busy interrupter BB is connected over contacts s4, p6, 39, 30, f6, to the windings 2 of relays A3, B3, the windings 1 of which repeat the signal to the calling subscriber, who hangs up and releases the connexion as described later. Supply of ringing-current and ringing-signal. If the wanted line is idle, the relay P is energized and (1) short-circuits its high-resistance winding 2 over contacts j5, p1, 36, k9, thus marking the line as busy in an ordinary call, (2) connects the ringing- generator RS to the called line over contacts l2, l3, p2, p3, the ringing-relay L having been energized as described in the preceding paragraph. When the relay V3 is de-energized, it opens at contact 37 the circuit of the relay G, but as this relay has its winding 1 short-circuited by contact e3, it releases slowly. So long as relay G is energized, the ring- ing-relay L is energized continuously over contacts q5, g1, is, 35 ; but after relay G de-energizes, it is energized periodically over contacts q5, p5, g3 and an interrupter SU. The relay L also connects a ring- ing-signal FT to the calling line. In the first non- ringing interval after the wanted subscriber replies, the relays A3, B3 are energized over their windings 1, and the relay As (1) by closing contact 45 energizes a relay E over contacts 45, f4, 40, lead a, contacts 2, Fig. 2, 10, 19, and coil RC, to battery, and (2) by closing contact 43 again energizes relay Q, which locks up over contacts q4, 44 and disconnects the ringing-relay L at contact q5. The relay B3 completes the circuit of a relay S over contacts 31, qz, 49, and the relay S locks up over contacts Sl, s2 and closes a further circuit for the relay G over contacts s3, q3, lead b to coil RC2, Fig 2. During conversation, the relays A3, B3, C3, E, G, S, Q all remain energized. Release by subscribers and metering calls. When the called subscriber hangs up, he frees his line so that he can call or be called ; but the release of the selectors and connector is controlled by the calling subscriber. If the called subscriber hangs up first., the relays A3, B3 release their armatures in such a way that the circuit of relay S is maintained over contact 46 before it is opened at contact 49. The relay B3 short-circuits the winding 1 of relay P over contacts j1, 50, q6, so that the relay P slowly de-energizes, removing the busy test from the called line, and connecting a "challenging tone" CT over contacts s4, p6, 39, 30,f6, to the windings 2 of relays A3, B3, and thence to the calling subscriber. When the calling subscriber hangs up, the relays A1, B1, V1, Fig. 2, are de-energized, and the relay B, connects the metering relay ZR to the lead b, so that it is energized over contacts 7, 3, b3, q3, Fig. 3, s3, and relay G. The relay ZR earths the test lead c through a low resistance w4, thus increasing the current therein sufficiently to operate the meter. The relay V1, Fig. 2, short-circuits the winding 2 of relay C1 over contacts 14, k2, and opens the circuit of winding 1 at contact 16, so that the relay C, de-energizes, removing the ground connexion to the test lead c1 and closing the circuit of the release magnet M1 over contacts 17, 5, k3. The removal of earth on the test lead c1 de-energizes the relay B, which energizes the release magnet M and removes ground from the test lead c2, thus de-energizing relay C3, Fig. 3, which energizes the release magnet M3 and opens the circuits of relays P, Q, S. Establishment of preferred call by trunk operator, Figs. 1, 2, 3, and 4. The second selectors IIGW and connectors LW are used in common for trunk and ordinary calls, but special first selectors TGW, wired in the same way as the second selectors, are used for the trunk calls, as shown in Fig. 1. In the system shown in Fig. 4, it is assumed that the trunk operator will communicate with a B-operator at the automatic exchange over an order wire, and that the B-operator will assign a junction over which the call is to be set up and will press the key K associated with that junction, thereby energizing a relay T, which connects the impulse sender I, II, III, IV, V to the junction and energizes a relay V. Operator's impulse-sender. The B-operator sets up the wanted number and starts her impulsesender, whereupon the arm II and cams I, III, IV, V revolve in unison. As the arm II moves from one contact to another, the cam I intermittently earths the lead a‹ ; but when the arm II reaches the depressed thousands contact, the relay X is energized, locks up, and disconnects the cam I from the lead a‹. Just before the second set of impulses is sent, the cam V unlocks the relay X, and the same process is repeated for the third and fourth sets of impulses. Preventing completion of connexion if A-operator fails to insert ping in jack of assigned junction. When the trunk or A-operator plugs in, the relay R, Fig. 4, is energized and (1) lights a lamp S and, (2) prepares a fresh circu