Patent GB-459233-A (GB)
Title: Improvements in or relating to two-motion switches of the type used in telephone systems and to circuit arrangements therefor
IPC: H01H67/16
Filed: 1935-06-01
Abstract: 459,233. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., and GOULD, J. R., 63, Aldwych, London. June 1, 1935, No. 15971. [Class 40 (iv)] Two-directional step-by-step selectors with a minimum number of relays and having no separate release magnet are controlled by leg-impulsing over one wire and change-over signals over the other wire, a register-controller being modified to give such control as required but to switch over automatically to loopimpulsing as soon as a call has been extended to a junction to another exchange or to a local final selector of ordinary type. The group selector shown in Fig. 1 employs only a single relay serving for change-over, testing, switching and holding, whilst in that shown in Fig. 2, the vertical magnet acts as a relay during rotary movement, no other relay being required. Figs. 6 and 7 show respectively double-wiper penultimate and final selectors with control similar to that in Figs. 1 and 2, whilst Fig. 5 shows an incoming selector which repeats incoming loop impulses so as to give the required leg control. Group selector ; first arrangement, Fig. 1. Ground on the negative wire operates relay H, and impulses over the positive wire operate the vertical magnet VM. At the end of the digit, ground is temporarily removed from the negative wire causing the closure of a selfinterrupting circuit for the rotary magnet RM over off-normal contacts NV2, relay H acting as the test relay over its right-hand winding, and locking over its left-hand winding to the incoming wire P. Release takes place by further stepping of the rotary magnet when relay H releases. Second arrangement, Fig. 2. Ground on the negative wire keeps magnet RM shortcircuited, whilst battery impulses on the positive wire operate the vertical magnet VM which is connected to ground over the incoming test wire. Vertical off-normal contacts NV1, NV2 busy the switch and connect up the rotary magnet, respectively, and at the end of the digit when ground is removed from the negative wire rotary hunting takes place with the lower winding of magnet VM acting as a test relay. When an idle outlet is found, the magnet operates, locks over its upper winding, opens the rotary magnet circuit, and switches through. A switch construction to enable the vertical magnet to act as a relay forms the subject-matter of Specification 459,287. Register-controller, Fig. 4. When seized, earth over sending-switch wiper S2 and relay D is connected to the negative wire to operate a selector relay such as H, Fig. 1, and ground impulses are transmitted over the positive wire and wiper S5 by relay PS which is operated in series with the sending- switch magnet SM. At the end of the digit, the usual relay SZ (not shown), operates to return the switch to normal and during this movement ground is removed from the negative wire in positions 13 to 15 of S2 to release the selector relay such as H, Fig. 1. The movement from positions 16 to 20 is under the control of springs MS to provide a sufficient inter-digital pause. When an outgoing junction or final selector with normal connections is reached, relay SW operates over the ground on the positive wire and switches over to a loop-impulsing circuit. Incoming selector, Fig. 5. Relays A, B operate and impulses of the first digit received are repeated to the vertical magnet VM. On the relapse of C, the rotary magnet operates, and one of the switching relays HA, HB energizes when an idle outlet is found. Ground is extended forward over the negative wiper and impulses of the next digit are repeated by relay A over rotary-off-normal contacts NR1 and the positive wiper, ground being temporarily removed from the negative wiper at the end of each digit during the interval between the falling back of relays C, G. When selection is complete, relay G operates over the positive wire to ground in the penultimate selector, releasing relays B, A, so that the feed is cut out. Penultimate selector, Fig. 6. Relay HA operates over the negative wire and vertical magnet VM is impulsed over the positive wire after which HA is released to connect up the rotary magnet. When an idle final selector is found relay HA or HB energizes over the incoming test wire P and relays BT, G, operate extending the incoming negative and positive wires to the outgoing positive and negative wires, respectively. At the end of the vertical movement of the final selector, relay BT is released and relay D operates in series with the upper winding of G over the incoming negative wire and operates B. At the end of the units digit, the removal of ground from the negative wire releases relays D, G, and the subsequent re-connection of ground operates CO to connect up feed relay A and ringing relay F. The release of D connects ground to the outgoing positive wire for testing. If the called line is busy, relay BT operates again over wiper PVR1 or PVR2 in series with the vertical magnet of the final selector, and relay G also operates and releases relay HA or HB and the final selector. Final selector, Fig. 7. Relay WS operates over the incoming test wire P1 or P2, relay H operates over the incoming positive wire and NR2, and the vertical and rotary magnets are impulsed over the negative wire, the release of H providing the change-over. The release of H also removes low-resistance battery from the incoming test wire causing relay BT, Fig. 6, to release. At the first rotary step, contacts NR1 operate magnet VM which locks to the incoming test wire whilst contacts NR3 disconnect the right-hand winding of WS so that this only remains operated to effect wiper-switching if its lefthand winding is included in the incoming test wire. At the end of the units digit, ground on the positive wire is applied to the upper winding of test relay H, and if the wanted line is free, H operates and releases VM. P.B.X. hunting. If a called line is the first of a group and is busy, relay HS operates releasing VM and closing a circuit for the rotary magnet RM which then interacts with the vertical magnet so that hunting occurs, if necessary, to the last line of the group at which a holding circuit is closed for VM. Contacts hs1 operate the vertical magnet of the penultimate selector to prevent the operation of relay CO, Fig. 6, until selection is complete. A rectifier in series with the upper winding of test relay H prevents HS from holding in series with it to ground h4.