Patent GB-201548-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1923-07-19
Abstract: 201,548. Western Electric Co., Ltd., (Assignees of Goodrum, C. L.). July 26, 1922, [Convention date]. Automatic exchange systems; selectors.-In a cross-bar group selector an incoming line and an idle one of a wanted group of outgoing trunks are simultaneously connected to a common link by the operation of a single bar member actuated by a single magnet. The invention is described with reference to cross-bar switches of the construction shown in Specification 183,438 in which incoming lines are connected to outgoing trunks through link circuits. When a connection has been made over a link circuit it is held by the energization of the horizontal magnet, the vertical magnets then being released and rendered available for completing further co-existing connections over other idle link circuits. As applied to a group selector each incoming line occupies a complete vertical row of contacts and has access to all the link circuits, each of which has access to one trunk in each outgoing group. In the system illustrated, Figs. 1 to 8, when arranged as indicated in Fig. 10, form a single circuit diagram. With a few exceptions the hundreds digit of a reference numeral indicates the figure in which it is to be found. A calling line is extended by a cross-bar line switch 100, Fig. 1, to an idle trunk leading to a cross-bar first group selector 200, Fig. 2, and to a cross-bar marking set selector 300, Fig. 3, which extends the calling line to an idle marking set, Fig. 4. The counting relays 405, 406 &c. lock up in pairs in response to the first series of impulses, on the cessation of which, one of a group of multi-contact relays 430 connects the marking wires to the vertical group magnets 211, 212 &c. of the engaged group selector 200, and the vertical magnet associated with the wanted group of trunks is energized over a selected marking wire. One of a group of multi-contact relays 330 is also energized and associates a relay testing- set 321, 322 &c. with the wanted group of trunks. The testing-set makes a double test for an idle trunk associated with an idle link circuit, and completes a circuit for the corresponding horizontal magnet which extends the call to a second group selector 500, Fig. 5, and a second marking- set selector 600, Fig. 6. The second marking-set selector 600 now extends the calling line to a second marking-set, Fig. 7, following whch the first marking-set selector 300 and the first marking-set, Fig. 4, are released. The second series of impulses cause the second marking-set, Fig. 7, to select a wanted group of trunks in the second group selector 500, and an idle trunk is engaged in the manner described with reference to the first group selector 200. The call may then be further extended over other group-selecting stages to a connector 800, Fig. 8, of known construction. Construction. of switches. The line switches,. marking switch selectors, and group selectors are similar in construction to the line switch described in Specification 183,438. Line switch 100, Fig. 1. The calling lines 131, 113, 101, 130 are divided into groups, the group. 131, 113 having access to link circuits 111, 112, while the group 101, 130 has access to link circuits 109, 110, all the link circuits having access to the outgoing trunks 114, 115. The trunks from the line switches may appear promiscuously in thegroup selectors. When a subscriber 101 removes his receiver, his line relay 105 energizes the vertical magnet 133 associated with the sub-group of lines 101, 131 &c. The magnet 133 rocks its bar and energizes the vertical magnet 116 or 118' corresponding to the first idle outgoing trunk 114 or 115. Assuming the trunk 114 is busy, the magnet 118 is energized over the front contact of a busy relay 117 and rocks its bar to prepare the corresponding vertical row of contacts for connection to an idle, link circuit. Marking-set selector 300. Fig. 3. This comprises a cross-bar switch similar in construction and in arrangement of incoming and outgoing lines to the line switch. The incoming lines, which are branches of the trunks from the line switches to the first group selectors, are divided into groups corresponding to the group selectors in which the associated trunks appear, each group occupying one or more vertical rows of contacts in the marking-set selector. For example, incoming lines leading from the trunks incoming to the group selector 200, Fig. 2, are assigned to the first two vertical rows 301, 302, the trunks 114, 115 shown, appearing in the row 301. The outgoing lines 316, 317 each lead to a marking-set such as that illustrated in Fig. 4. The vertical magnet 118 of the line switch closes a circuit over conductor 133 for the vertical magnet 311 of the marking-set selector, the latter magnet rotating the associated bar and energizing the vertical magnet, say 314, corresponding to a trunk 317 leading to an idle marking-set. The magnet 314 (1) rotates its bar (2) energizes the impulse relay 400 of the selected marking-set, Fig. 4, over conductor 335, and (3) closes a circuit over conductors 336, 134 for a horizontal magnet 337 corresponding to an idle link 309. Immediately the connection is extended through the marking- set selector, the horizontal magnet 337 locks upover conductors 338, 339 and the left-hand contact of slow-release relay 401 (energized by the response of the impulse relay 400), and a circuit is closed for the horizintal magnet 106 corresponding to an idle link 110 at the line switch, over the grounded conductor 338, test wires 235, 135, and working contacts of magnets 118, 133, 105. The magnet 106 locks up over grounded conductors 136 and extends the starting circuit to the next horizontal magnet 107. The cut-off relay 104 is also energized over the grounded conductor 136 and the magnets 105, 133, 118 are de-energized in turn. The magnet 118 opens the circuit of the vertical magnet 311 of the marking-set selector and the relapse of the magnet 311 de-energizes the vertical magnet 314. Relays 119, 315 energize over the grounded conductors 135, 339 and extend the starting circuits to the next idle vertical magnets. The connection over the line switch and the marking-set selector is now held by the horizontal magnets 106, 337, and the vertical magnets 118, 133, 311, 314 may be used to set up other connections. Marking set, Fig. 4. On the extension of the call to the marking set the impulse-relay 400 is energized over the calling subscriber's line and the apparatus is in a condition for receiving the first series of impulses. In response to the first impulse the relay 400 relapses and a circuit is closed for a slow-release relay 402 which in turn energizes another slow-release relay 404. The first lower-counting relay 406 is also energized and clases a series circuit for the upper-counting relay 405 which, however, is at this moment shortcircuited over the back contact of relay 400. When the impulse-relay 400 pulls up, this short-circuit is removed and the relay 405 energizes and locks up in series with the relay 406. At the next impulse the relay 408 is energized over the lower front contact of relay 405, and on the cessation of this impulse locks up in series with its made 407. This operation is continued, a pair of counting relays locking up at each impulse. Assuming the first digit is 3, on the cessation of the third impulse the slow relay 402 falls back and energizes a relay 403 which closes a circuit 414, 343, 344 for a multi-contact relay 411, which locks up and extends the marking wires from the counting relays to the vertical group magnets 211, 212 &c. of the selector 200 engaged in the connection, this selector being identified by the vertical row of the marking-set selector in which the incoming trunk 115 appears. First-group selector 200, Fig. 2. Relay 403 also completes a circuit 414, 418, 345, 346 for the group-selector vertical magnet 236, which prepares for connection the contacts of the vertical row occupied by the incoming trunk 115. At the same time the vertical magnet 211 controlling the vertical contact row representing the wanted outgoing group is energized over the selected marking wire 420 and the conductor 421. A multi-contact relay 318 individual to the wanted group is also energized in parallel with the vertical magnet 211, and associates a set of testing relays 321, 322 &c. common to the group selector 200, with the wanted group of outgoing lines. The right-hand windings of the test relays 321, 322 &c. are directly connected to the armatures of the link circuit busy relays 217, 218 &c., whilst their left-hand windings are connected over the contacts of the multicontact relay 318 to the test wires 227, 230 &c. of the wanted group of trunks. All the test relays, therefore, associated with either a busy trunk or a busy link circuit pull up, and prepare a circuit for the lowest horizontal magnet corresponding to which both the link circuit and the trunk to the wanted group are idle. Assuming the trunk 221 is the only idle one simultaneously associated with an idle link, the test relay 321 is the only one remaining inert and on the relapse of the slowrelease relay 404 a circuit 414, 415, 352 is completed for the horizontal magnet 213, which looks up over the grounded conductor 239 and operates its bar to extend the trunk 115 over the link 206 to the outgoing trunk 221 leading to a second group selector 600. Marking-set selector 600, Fig. 6, at second group selecting stage. The vertical magnet 610 controlling the vertical contact row occupied by the trunks of the selected groups is energized over the conductor 415, a pair of contacts of the multicontact relay 318 individual to this group, and the conductor 353. The magnet 610 closes a circuit for a vertical magnet 616 of a contact row individual to an idle marking-set, Fig. 7, at which the impulse relay 700 and series relay 701 are energized. A horizontal magnet 620 of an idle link