Patent GB-191405115-A (GB)
Title: Improvements in Metering Systems for Machine Switching Telephone Exchanges.
Filed: 1914-02-27
Granted: 1915-02-25
Abstract: 5115. Western Electric Co., [Woodward, F. T, acting for Western Electric Co.]. Feb. 27. Automatic exchange systems; metering systems. - The operating- circuit of a subscriber's meter includes contacts on two sequence switches, and the circuit is completed through these switches during the release of the connexion only if the connexion has been established, and the called subscriber has replied. The extension of the call, and the removal of the receiver by the called subscriber, move the second of the two sequence switches to different positions, thus determining the position from which the release is started and the possibility of the metering- circuit being closed during the release. General operation of the system. Fig. 1 shows a subscriber's lines 120, and a first callfinder by which they are connected to a second call-finder, Fig. 2, which finds an idle registering and controlling equipment, to which the leads at the bottom of Fig. 2 make connexion. The contacts of a group selector and a sequence switch 600 are shown between the dotted lines in Fig. 2, and parts of a final selector and a sequence switch 300 are shown at the extreme right of the Figure. Call-finders. When the subscriber calls, the line relay 121 is energized, thus completing a circuit for the pilot relay 122. which in turn completes a circuit for the power magnets 123 of the line finders. When the brush 128 reaches the terminal 132, a circuit is made through the spring 102 bottom, high-resistance winding of relay 135, spring 108 top, to contact 136. The relay 135 brings its low-resistance winding into circuit to reduce the test potential on this line, and the call-finder moves to bring its brushes accurately on the terminals of the calling line. The contact 136 being then broken, this part of the circuit is replaced by one through the relay 137 and spring 106 bottom. The relay 137 opens the circuit of the power magnet 123 and closes one for the holding-magnet 138, at the same time making a circuit over the spring 105 top, to drive the sequence switch 100 from its first to its second position. This movement opens the circuit of the relay 137 at the springs 102. 108, so that the sequence switch 100 stops in its second position. The closure of contact 110 brings the cut-off relay 139 and the meter magnet 55 into circuit. The current in this circuit is not sufficient to energize the magnet 55, but the relay 139 de-energizes the relays 121 and 122. Calling potential is now placed on the terminal 234 of the second line finder through the closure of the contacts 107 top, 106 top, and 108 bottom, and the motor magnets of the group of second line finders are brought into circuit by the closure of contact 113. One of the line finders connects itself to the line in the usual way, with the result that the sequence switch 600 is moved to its second position, and maintains busy potential on the line over the contact 610. This movement of the sequence switch 600 also closes a circuit over the spring 611 bottom to drive the sequence switch 200 to its second position. When the second line finder reached the calling line, the relay 137 was energized, thus moving the sequence switch 100 to its fifth position, and a circuit is now made for the cut-off relay 139 and meter magnet 55 over the spring 102 top, relay 135, spring 207 top, and resistance 299. The current in the circuit is not sufficient to energize the meter magnet. The calling line is now extended to the repeater coil 239 over the springs 210, 211. Connexion to operator's register. When an idle registering and controlling set has been found, the sequence switch 600 is moved, by a circuit including the spring 653, into its third position. The sequence switch 200 is then moved to its third position by a circuit over the spring 611 top, and thus connects the calling line to the controlling set over the springs 210 top and 211 bottom. When the registration of the number has been completed, the sequence switch is driven to its fourth position by a circuit over the spring 206 bottom. Group selector. The third position of the sequence switch 600 connects the group selector to the controlling set over the contacts 612, 652, and the closure of this circuit moves the sequence switch to the fourth position. After the setting of the group selector, the sequence switch 600 moves to the fifth position, and after the trunk-hunting operation it moves to the sixth position. Final selector. The closure of the contacts 616 bottom and 617 top connects the controlling set to the final selector, and the closing of this circuit moves the sequence switch 300 to its second position. After the first selection (brush selection or tens selection) the sequence switch 300 moves to its fourth position; and after the final selection (line selection or units selection), it moves to its fifth position, to test the desired line. If the line is idle, the sequence switch 300 moves on to its twelfth position; if the line is a private branch exchange line and is busy, a further selection takes place in the sixth position of the sequence switch, and if an equivalent idle line is found, the switch moves on to the twelfth position in this case also. If no idle line is found, the sequence switch stops in its tenth position. In the meantime, the sequence switch 200 has been moved to its fourth position on the completion of the registration by an impulse over the spring 206, and at the end of the selection, the sequence switch 600 was moved to its seventh position by an impulse over the spring 653. This movement causes the closure of the spring 611 bottom, thus moving the sequence switch 200 to its fifth position. As the sequence switch 300 passes through its eighth position, the contact 309 bottom is closed, thus energizing the supervisory relay 248, which provides a circuit to drive the sequence switch 200 into its eighth position. In this position the busy tone 271 is connected to the calling subscriber's line, but in the case when the desired subscriber's line is idle, this is immediately cut off, by the movement of the sequence switch 200 into its eleventh position, this being caused by a second energization of the relay 248, as the sequence switch 300 passed from its eleventh to its twelfth position. In this position ringing current is sent to the called subscriber's line over the contacts 310 bottom and 311 bottom, and the ringing tone 272 is connected to the calling subscriber's line to indicate that the call is being made. When the called subscriber replies, the sequence switch 300 is moved to its thirteenth position and the connexion thus obtained over the springs 310 top and 311 top energizes the relay 248 and moves the sequence switch 200 to its fourteenth position. Release; metering. When a call is successful, conversation takes place with the sequence switch 100 in its fifth position, switch 200 in its fourteenth position, switch 300 in its thirteenth position, and switch 600 in the seventh position. When either subscriber hangs up, the sequence switch 600 is energized by a circuit over the spring 209 bottom, and over either the spring 252 or 203 according to whether the supervisory relay 241 or 248 is deenergized. The sequence switch 600 moves to its eighteenth position, and in doing so opens the contact 610 in the circuit of the relay 137, which then completes a circuit over the spring 105 bottom to drive the sequence switch 100 into its ninth position. The movement of the sequence switch 600 into its eighth position completes a circuit over the spring 611 top to drive the sequence switch 200 from its fourteenth to its normal position. While the switch 200 is passing its fifteenth, sixteenth and seventeenth positions, the battery 298 is connected to the spring 207, and in the case considered in which the call has been successful and the sequence switches 100, 200 start from their fifth and fourteenth positions respectively, the contacts 207 bottom and 102 top will at some time be closed together and the meter magnet 55 will be energized. If the calling subscriber has hung up his receiver, the sequence switch 100 moves to its normal position, but if the line 120 is still closed, the switch remains in its ninth position, the relay 137 being energized over a circuit including the springs 112 top, 111 bottom and 108 bottom. This circuit is broken and the switch 100 moves on when the subscriber hangs up. When the sequence switch 600 reaches its eighteenth position, the group selector restores in known manner, and the switch 600 moves to its normal position. When the sequence switch 300 reaches its sixteenth position, it waits till the called subscriber hangs up, then moves to its eighteenth position and starts the restoration of the final selector, and finally moves to normal position. Release in the case of an uncompleted connexion. If the desired line is busy, the sequence switch 300 stops in its tenth position, the sequence switch 200 being in this case in its eighth position. The busy tone 271 is connected to the calling subscriber's line in this position, and when he hangs up his receiver, the supervisory relay 241 completes a circuit over the springs 252 and 209 top to start the restoration to normal as before. In this case, however, the sequence switch 200 starts from its eighth position, and the contact 207 bottom is not closed until after the contact 102 top is opened, so that metering does not take place. If the connexion is made to the desired subscriber, but lie does not answer, the calling tone 272 is applied to the line of the calling subscriber, over the contacts 212 top and 213 bottom, and when the calling subscriber hangs up, the restoration is started by a circuit for the sequence switch 600 over the contact 252 and spring 209 bottom. The restoration takes place as before, but the sequence switch 200 now starts from its eleventh position, and the metering circuit is not close