Patent GB-133338-A (GB)
Abstract: 133,338. Western Electric Co., Polinkowsky, L., and Deakin, G. Jan. 2, 1918. Semi-automatic exchange systems; metering systems.-In systems in which calling-lines are automatically extended to an operator's position and are further extended over automatic switches under the control of the operator, and in which, when an operator leaves her position, the extension of calls to that position is normally prevented, means provided at a particular operator's position (concentration position) serve, when operated, to permit the extension of calls to an adjacent position at which no operator is on duty, in such a manner that the operator at the concentration position may set up the call and supervise the connexion by means of the common equipment of her own position. Adjacent operators normally have access to different groups of calling lines, so that, when the calls are concentrated on a particular position, the concentration operator has access to a number of such groups. An ordinary position is converted into a concentration position, when the operators at adjacent positions go off duty, by means of switches brought into operation by the depression of concentration keys, these switches effecting the necessary changes in the circuits of the adjacent positions. These switches are not operated unless the plug of the neighbouring operator's telephone set is withdrawn from the jack. Normally, the free cords. of a position are rendered inoperative when a call is awaiting attendance, but when concentration is effected, calls can be extended both to the concentration and adjacent positions whether or not a call is awaiting attention. In systems in which calls from other exchanges are handled over trunks terminating on the usual semi-automatic B-operator's position, this position is arranged adjacent to the concentration position,. so that such calls also may be dealt with at night on the concentration position, means being provided to prevent the simultaneous connexion of the concentration operator's telephone to a local call and to the order wire to the other exchange. The invention is described as applied to a system in which a calling-line is connected by first and second line-finders to a cord individual to a group-selector, of which the brushes 276, 278, 279 are shown in Fig. 1. Individual to the cord are controlling sequence switches 220, 250, Fig 1, and a searching sequence switch 330, Fig. 2, which extends the cord to the A or B register of the position, or, if these are not available, to an adjacent position. Fig. 2 also shows the searching sequence switches 430, 530 of the left and right adjacent operators, the left operator being an ordinary A-operator and the right operator being a B-operator connected by an order wire 570 to a distant exchange. The sequence switch 350 is individual to the centre position and serves to isolate the free cords of the position for a predetermined time after a call has been received, as described in Specification 105.266. The sequence switches 380, 390 are individual to the A and B registers of the position. Sequence switches 480, 580 are brought into operation by the depression of the concentration keys 367, 368 respectively, and serve to make the necessary connexions between the cords of the adjacent positions and the position equipment of the concentration operator. The contacts controlled by the various sequence switches are included within the areas indicated bv the dotted lines. The operation of the system when the concentration arrangements are not in use will be first described. Line-finders. When a subscriber removes his receiver, his line relay 201 puts selectable potential on terminal 210 and energizes the common starting-relays 204, which complete circuits for the power magnets 211 of the free first linefinders in the group. When one of these reaches the calling-line, relays 214, 212 are energized in the usual way, relay 212 disconnecting power magnet 211, putting selectable potential on terminal 230, and energizing the common starting-relays 316 of the second line-finders. The relays 216 close a circuit over a relay 219 and contact 352 of operator's switch 350, for relay 252, which energizes power magnet 261 to rotate the second line-finder. When the calling-line is found, a circuit is closed .over terminal 230, contact 256, high-resistance right-hand winding of test relay 264, contact 353 of switch 350, and contact 255 of switch 250. The test relay 264 completes a parallel circuit through its left-hand winding and relay 262, which opens the circuit of the powermagnet 261 and moves the sequence switch 250 into its fourth position. As the switch 250 moves from its second to third position, the sequence switch 220 is momentarily energized over contacts 222, 266 and moves into its fourth position. In the second and later positions of switch 220, a circuit is closed for the cut-off relay 207 and meter 208, over relays 213, 227, back contact of hold-over relay 225, normal contact of metering- hindering relay 224, contacts 223 top and 258 top,. to ground. Relay 207 disconnects the line relay 201, which de-energizes relays 214, 212, relay 213 remaining energized over its left-hand winding Relay 227 connects the calling-line to contacts 232, 233 in preparation for the extension of the call to the operator's position. If two second line-finders simultaneously make connexion with the calling-line, the connexion is automatically released. As the switch 250 moves into its second position after connexion has been made with the calling-line, the high-resistance winding of the relay 264 is open-circuited at contact 255, and the current through the relay 262 is insufficient to maintain it energized if it is in parallel with a similar relay. A circuit is therefore closed for the release relay 263 over its left-hand winding contact 267 top, back contact of relay 262, and front contact of relay 252. Release relay 263 causes the switch 250 to make a complete rotation without moving the switch 220 from its first position. Operation of timing-switch 350 for marking the operator's position busy. A relay 349, Fig. 2, energized in parallel to the sequence switch 250, closes a circuit over contacts 493, 593 of the concentration switches for the timing-switch 350, which moves out of its first position, thereby insulating on contacts corresponding to contacts 352, 353 the remaining free cords of the position, and completes a cycle operation under the control of interrupter 376 after a predetermined time, which time is prolonged if either or both of the relays 354, 355 are energized, that is, if one or more other calls are awaiting attention, as described in the above-mentioned Specification. As the initial circuit of the switch 350 includes contacts closed only in the normal positions of the concentration switches 480, 580, the timing-switch is not operated when concentration is effected. Connexion to idle register. With switches 220, 250 each in its fourth position, the searching- switch 330 rotates to find an idle register, preference being given to the A-register and then to the B-register of the home operator, but if neither of these is available, connexion is made to the A or B registers of the adjacent operators if disengaged. As the switch 330 rotates, contact 332 intermittently earths the right-hand winding of the test relay 264 over contacts 332, 586. Assuming that the A-register is free, the relay 264 is energized in the first or seventh position of switch 330 over lead 309, contact 333 bottom, right-hand winding of relay 381, contacts 382, 397, armature of relay 361, and contact 356 closed by the operator's telephone plug. Relay 264 completes a parallel circuit through its left-hand winding and relay 262, which arrests the switch 330 and moves the switch 250 into its eighth position. As the latter passes through its sixth position, it closes contact 271 top to move the switch 220 into its fifth position, wherein the calling-lamp 270 is flashed in series with the pilot relay 358 by an interrupter 236, and the calling-line is extended over contacts 232, 233, leads 313, 314, contacts 334, 335 of switch 330, back contacts of relay 360, normal contacts of key 369, to the operator's telephone circuit 378. Relay 381 moves the switch 380, individual to the A-register, into its fifth position and closes a holding- circuit over its left-hand winding in series with its right-hand winding. (If the A-register had been in use and its register had reached its seventh position, wherein the register has been set and the keyboard disconnected, connexion would have been made to the B-register in the second or eighth position of switch 330, the test relay 264 being then energized over lead 309, contact 339 bottom, left-hand winding of relay 391, contacts 392, 384, and armature of relay 361). Selection of wanted line. The operator communicates with the calling-subscriber and depresses the keys corresponding to the number of the wanted line, whereupon the register sequence switch 380 moves into a position wherein the fundamental circuit is controlled by the counting- relays, of which the last pair 320, 323 only are shown. As the switch 380 moves into its seventh position, a circuit is closed over the armature of relay 381 and contacts 388, 338, wire 312, contact 241, to move the switch 220 into its eighth position, in which the ringing-lamp 240 is flashed by the interrupter 236. The fundamental circuit is now closed from relay 252 over contacts 269, wire 310, contacts 336, back contact of zero counting- relay 320, stepping-relay 324, and contact 387 bottom, to ground. The relay 252 moves the switch 250 into its ninth position, in which the tripping-spindle is set by its power magnet 273 in the usual manner, causing an intermittent deenergization of the stepping-relay 324, which controls the counting-relays in known manner. When the last pair