Patent GB-191326905-A (GB)
Title: Improved Circuit Arrangements for Telephone or other Systems.
Filed: 1913-11-22
Granted: 1915-07-08
Abstract: 26,905. Siemens Bros. & Co., Laidlaw, E. A., and Grinsted, W. H. Nov. 22. Automatic and semi-automatic exchange systems; metering-systems.-In a system in which the second and subsequent selectors are controlled by impulses repeated from the first selector, the stepping- magnets of the selectors are arranged to be energized at the the termination of each line impulse instead of at its commencement. Arrangements are described for metering and for controlling the second and subsequent selectors over a two-wire trunk. First and second preliminary selectors IVW, IIVW. These operate in the usual way to extend the calling-line to a group selector IGW, the cut-off relays T, T1 remaining energized by their lowresistance windings 1, which are in series in the test-circuit c. First group selector IGW. The line relay A, energizes a relay V1 which prepares the circuit of a relay V2, both these relays being of slow - release type. In response to the first line-interruption of the series representing the first digit, the relay A, energizes the relay V2, which prepares the circuit of the vertical magnet H1, so that this magnet is energized at each subsequent energization of the relay A1. At the end of the series of interruptions, the relay V2 de-energizes and completes the cirouit of the rotary magnet D2. When an idle line of the selected group is found, the winding 1 of the test relay C is energized in series with a relay C1, Fig, 2, over the b-lead of the junction line a, b, the circuit including also the line A2 of the second selector, which is connected to the incoming b-lead by the test-wire C2. The relay C locks itself over the winding 2 and marks the line busy by grounding the test-wire C1. The relay C1 locks itself through a relay C2 so as to be independent of the o junction lead, from which it is disconnected at the contact 30. Second group selector IIGW. In addition to the line relay A2, the relays Q, V4, C3 are energized when the selector is seized. The relay C3 disconnects the relay A2 from the wire C2 and connects it to the junction lead a, over which the second series of interruptions is repeated by the contact 17 of the relay A1, the relay V: being energized as before. At the first interruption, the relay A2 energizes the winding 1 of a relay B, which renders itself sluggish by short-circuiting its winding 2 at b., so that it remains energized until the interruptions cease. At each re-energization of the relay A2, the vertical magnet H2 is energized at the contact 33. After the last interruption, the relay B de-energizes and connects the rotary magnet D, in circuit. When the terminals of an idle connector are found, the relay B is energized over the winding 2 and locks itself over the windings 1, 3. The outgoing test-wire is grounded at b4 to mark the seized line busy. The relay C3 is unlocked at the contact b5 and disconnects the relay A2 from the junction wire a. Connector LW. The relay V5 connects the relay A3 to the a side of the incoming line, over which the third and fourth series of interruptions are repeated by the relay A1. The relay V5 also energizes a relay L, which energizes the third winding of a relay Y, and the relay A3 energizes a relay C4, which locks itself to the incoming test-wire. At the first interruption, the relay A3 energizes a relay V6, which locks up the relay Y independently of the normal contact k5, and at each re-energization of the relay A3, the vertical magnet H3 is energized at the contact 53. After the last interruption of the third series, the relays V6, Y are de-energized, so that the interruptions of the fourth series are repeated to the rotary magnet D4. As soon as the connector commences its rotary movement, the control of the relay V5 is transferred by the rotary off-normal contact i5 to the contact 61 of the relay V6, so that the de-energization of the relay V6 at the conclusion of the series is followed after a momentary interval by the de-energization of the relay V5. Busy test and signal. The de-energization of the relay V6 completes a circuit through both windings of the test relay P. If the wanted line is busy, the relay P fails to energize, and the de-energization of the relay L, following upon that of the relay V5, connects a busy tone device BB to the third winding of the relay Y, which repeats the signal inductively to the calling subscriber, who releases the connexion as described later. At the same time, an interrupter u4 intermittently energizes the relay Y, which may serve, in a semi-automatic system, to transmit a flash signal to the operator. Supply of ringing-current; ringing signal. If, however, the wanted line is disengaged, the relay P becomes energized and marks the line busy by short-circuiting its second winding at the contact p1. The relay L being already energized, ringing-current is connected to line by the closure of the contacts p2, p3, but after a moment, the relay V5 de-energizes and puts the ringing-relay L under control of an interrupter SU. At each energization of the relay L, a ringing-tone device is connected over contacts 51, l4 to the third winding of the relay Y, which repeats the signal inductively to the calling subscriber. When the called subscriber replies, the relay Y is energized and energizes the relay V6, which cuts out the ringing relay L. Release. The release is controlled by the calling subscriber, but if the called subscriber should be the first to hang up his receiver, his line is at once rendered selectable to other connectors, since the de-energization of the relay Y short-circuits the winding 1 of the relay P, which de-energizes and removes the busy potential from the test-wire c4. The called line is now disconnected at the contacts p2, p3, and the calling subscriber hears the busy signal BB. When the calling subscriber disconnects himself, the relays A1, V1, C are de-energized, and a circuit is completed for the release magnet M, of the first group selector. The magnet M1 opens the incoming test circuit c, so as to unlock the relays T, T1, and the first preliminary selector moves forward till it regains its normal position. The release of the first group selector de-energizes the relays C1, C2, Q, V4, Fig. 2, and the relay B energizes the release magnet M, of the second group selector. The release of the second group selector deenergizes the relay C4, Fig. 3, which unlocks the relay V6 and energizes the connector release magnet M3. Metering. The meter Z is connected in parallel with the winding 1 of the cut-off relay T, but is not actuated by the normal current in the test circuit c. It is energized upon the initiation of the release of the connexion. During the movement immediately following the energization of the relay V1, while the release of the first group selector is retarded by the relay C, which is rendered sluggish in releasing its armature owing to its short-circuited winding 1, the metering relay ZR is connected by the contact 20 to the b-side of the line and is energized over the contacts 49, 62, Fig. 3. The relay ZR increases the current in the test-circuit c sufficiently to energize the meter Z, by cutting a low resistance w4 in parallel with the resistances w1, w2. In the case of an unsuccessful call, the relay V,. Fig. 3, is not energized, and the circuit of the metering-relay is there fore not completed. Release of the first preliminary selector when the subscriber abandons the call without calling the wanted number. The arrangement is such that, in this case, the release magnet M1 is energized and opens the test circuit c to unlock the relays T, T1.