Patent GB-191415546-A (GB)
Title: Improvements in Selecting Devices for Telephone or other Circuits.
Filed: 1914-06-29
Granted: 1915-08-05
Abstract: 15,546. Siemens Bros. & Co., Pettigrew, T., and Christian, D. A., [Siemens & Halske Akt.-Ges. (partly)]. June 29. [Addition to 818/13.] Automatic and semi - automatic exchange systems; metering systems.-Relates to systems of the kind described in the parent Specification, in which the arms of selecting-switches hunt over a row of contacts divided into groups, and are arranged to rest on the contact of an idle line in a selected group. Systems are described in which some of the bank contacts of the switches are connected to lines of ordinary subscribers having a single line, and others are connected to the lines of sub-exchanges or private branch-exchanges. In the case of a connexion to a sub-exchange &c. having a number of lines connected to contacts on the switches. this group of contacts is placed in selectable condition by means of a relay energized from the line connector, or by means of a special number selector called a digit switch. The hunting-switch that finds an idle line in the group is called a discriminator. Means are described for applying ringing-current to the called line, and for interrupting a local call in favour of a trunk call. Fig. 3 shows a system in which, when the arms 1, 2, 3 of the connector LW rest on the contacts of a private branch-exchange having a number of lines, a relay E is energized, thus actuating the contacts e3, e4, e5 to enable the discriminator DS to find an idle line in the group belonging to the private branch-exchange. Some of the bank contacts of the connector LW connect to single-line subscribers. The operations in the case of a connexion to such a subscriber will be first described. Connexion to a single-line subscriber. When the connector is taken into operation, the relay C is energized over the lead c, and the relay A is energized and de-energized while the number impulses are coming in. The impulses actuate the vertical magnet H through the contact a' of the relay A. A slow-acting relay V is included in the circuit of the magnet H, and this relay also brings into circuit another slow-acting relay V<1>. When the lifting-impulses cease, the relay U is energized over the contact v3 and the normal contact i1, thus connecting in the rotary magnet D. When the arms 1, 2, 3 of the connector have reached the desired line, and this line is free, the test relay P is energized by a circuit proceeding from battery on the test lead of the desired line over arm 3, 'contacts g1, v<1>1, v<6>, p<r>1, n2, s1, winding of relay P, and contact c2. The test relay P short-circuits its high-resistance winding at the contact p1, thus marking the line as engaged, energizes the ringing-relay L over the contact p3, and connects to the wanted line over the contacts p5, p6. The relay L is periodically energized over a tenseconds switch, and connects the ringing- generator over the contacts l2, l3. The free tone is connected to the winding III of relay Y, and is repeated to the calling line over the windings I, II. When the called subscriber replies, the windings I, II of the relay Y are energized over his line, and the relay Q is energized over the contact y2. This relay opens the circuit of the ringing-relay L. When the called subscriber hangs up his receiver, the relay Y is de-energized, and the release magnet M is energized over contacts y3, q4. A metering- potential is applied to the b-line over the contacts q3, g3 to operate a register in the manner described in Specification 1157/14. If the wanted line is busy, the busy back signal is connected to the winding III of relay Y. Trunk-call connexion to single-line subscriber. After the connector has been taken into use and the relay C has been energized, the trunk operator temporarily energizes the relay F over the b-lead as described in the above-mentioned Specification. The relay G is thus energized over contact f2 and holds the testing-circuit open at the contact g1, until the operator again energizes relay F and completes the testing- circuit over contact f4. The relay P connects ringing-current to line as before. When relay F is released, relay N is energized by a circuit over off-normal contact i7, contacts v<1>4, g6, p8, e16, e6, and winding II of relay N. This relay connects the test lead directly to earth over the contacts n2, n4 and connects the speaking leads over contacts n6, n7. The release magnet M is only energized when the operator releases the connexion, as its circuit is held open at the contact g4. When the wanted line is engaged in a local call, the test relay P is not energized, but after the release of the relay F, a circuit for the relay S is completed over contacts f1, p9, g8, v<1>5 and arm 7. The contact S, of this relay connects winding I of the relay N in the test circuit, and this winding receives enough current to energize the relay, which locks itself over its winding II and directly earths the test lead. The speaking lines now being connected over the contacts n6, n7, the trunk operator announces the trunk call and, by energizing the relay A, applies a de-energizing potential over the contacts a3, a4. Connexion to a multiple-line subscriber or exchange. The connector is set on the desired terminals, and the test relay P is energized in the same way as for a single-line subscriber. When the ringing-current is applied, the relay E is energized over its winding I and locks itself over its winding II. The contact e1 of the relay E brings the motor magnet Dr of the discriminator DS into circuit. As soon as the arm 7 moves from its normal position, the relay Pr is energized, and locks itself, and the discriminator moves until an idle line in the desired group is found, whereupon a test circuit is completed over one of the contacts e3, e4, e5, the arm 6, and the relay P. The contacts p<r>2, p<r>3 having been opened, the speaking leads are connected over the discriminator arms 4, 5. The release of the connector takes place as in the previous case, and when the relay C is deenergized, the circuit of the relay P is interrupted at c2, and the magnet Dr of the discriminator is again brought into circuit at the contact p,. When the arm 7 reaches its normal position, the relay S is again energized, and the circuits of the relays E, Pr are opened. Trunk-call connexion to multiple-line subscriber or exchange. If one of the lines of the subscriber is idle, the connexion is made as described above; but if all the lines are busy and the arm 7 again reaches its normal position, the relay S is energized when relay F is released and the winding I of the more sensitive relay N is connected to the test arm 6. When a line that is engaged in a local call is reached, the relay N is energized, locks itself over its winding II, and earths the line directly over its contact n2. The release in this case is brought about by the trunk operator, who, by de-energizing relay C, opens the circuit of relay N and so closes the circuit of the driving-magnet Dr. Fig. 4 shows a system in which the contacts of a certain level of a group selector GW are reserved for sub-exchanges, or private branchexchanges, or subscribers with more than one exchange line. The last set of number impulses is received by a digit switch HS, which selects the desired group, and the discriminator DS1 finds an idle line in that group. When the idle connector SLW is taken into use, the relay V is energized, and thus connects winding II of relay A to the line a0. The relay A energizes the relay L over the contact a2, and the relay C over the contact a,. When the number impulses come in and the relay A is actuated by them, the relay V<1> is energized over the contact a4. The relay A also controls, at the contact a1, the circuit of the magnet H of the digit switch HS. It is assumed that three impulses are received, and hence that the arm 1 is connected to the magnet D, of the discriminator DS1, and the arm 2 characterizes all the lines of the wanted subscriber. The relays V, V<1> de-energize when the number impulses cease, and the magnet D1 is brought into circuit over the contact v1 and the interrupter. When the arms a, b, c, d reach an idle line in the group on which the arm 2 has been set, the test relay P is energized in a circuit over contacts c7, v<1>1, winding I of relay P, contact s1, arms 2, d, c, and battery on wanted line. The relay P locks itself over the contact p1 and its winding II, and makes the line busy by connecting it to earth over the low resistance w1. The ringing- circuit is prepared at contacts p2, p3, and the circuit of the magnet D, is opened at contact p4. The relay S<1> is energized over the contact p7, and connects the ringing relay L to an interrupter over the contacts s<1>3. When the wanted subscriber replies, the windings II, III of relay Y are energized over the wanted line, thus connecting the relay A to the line a, over the contact y2, and energizing the relay V<1> over the contact y3. The relay V<1> cuts off the ring- ing-relay at the contact v<1>3, and applies registering potential to the line b0 at the contact v<1>4. Release. When the called subscriber hangs up his receiver, the relay Y is de-energized, thus short-circuiting the holding-winding of the relay P at the contact y<1>, and the busy back signal is connected to the winding I of relay Y to indicate to the calling station that the called station has disconnected. When the calling subscriber hangs up his receiver, and the group selector GW is released, relays A, Care deenergized. The circuit of the magnet D1 of the discriminator DS, is completed over the contact c3 and the off-normal contacts i1, i2, and the arms are driven to normal position. When the contact i1 is restored, the magnet H is energized to drive the digit switch HS to normal position. Busy test. If the lines of the wanted subscriber are all engaged, the arms of the discriminator rotate until the arm c reaches its grounded contact, whereupon the relay S is en