Patent GB-318945-A (GB)
Title: Improvements in and relating to automatic and semi-automatic exchange systems
IPC: H04Q3/42
Filed: 1928-06-13
Abstract: 318,945. Standard Telephones & Cables, Ltd., (Deakin, G., and Polinkowsky, L,). June 13, 1928. Automatic exchange systems. - Marking switches common to a number of single motion power-driven selectors are themselves powerdriven and are controlled by a register controller' of reverting impulse type. The groups of trunks in the selector banks may be of different sizes and the members of a group mav appear anywhere in the banks. The marking switch is operatively associated with the selector by a preiiminary hunting movement of the marking switch when the register controller is ready to receive the reverting impulses. During the units setting of the connector and while it is hunting for a P.B.IX line, the marker and connector advance alternatelv one terminal at a time. Special two-digit numbers and the occurrence of a permanent call due for example to a fault cause the line to be extended to an operator. In the case of faults, the operator is able to cut out the feed bridges at the first selector to enable the line to be tested, If a selector fails to find an outlet Within a given time interval, the register controller sends back busy tone via the out-control wires and the bridge condensers and if the subscriber fails to hang up within a further interval an alarm is given. Certain of the above features are claimed in Specifications 318,956, 318,957 and 319,063. Mounting and arranging switches. The switches and relays are mounted in vertical-bay units which are wired up in the factory, external connections being brought to a terminal strip at the top of the units. The system comprises the following units, (1) a three-bay unit with, 14 call finders, 12 connectors and 2 connector-marking switches in two bays and all the relays in the third, (2) 20 group selectors, 2 marking switches and the relays all in one bay, (8) a three-bay unit for 16 register-controllers, the associating and time alarm switches being in the centre bay and the registers and relays in the outside bays. The switch racks are made in small units, each with a separate motor and with means whereby, at slack times, the motor is started only when one of its switches needs to he driven. 1st finder. Line relay Lr and starting relays Fsr, Asr pull up and energize the power magnets PF of all idle finders. When the line is found, Ltr in the successful finder energizes Lhr in series with the 2nd finder starting relay Csr. Lhr shunts out Fsr by the low resistance holding winding of Ltr. If all the finders are busy, Lgr over which the power magnets are energized is unable to pull up and lamp LGL glows. 2nd finder. The 2nd finders are arranged in sub-groups of 10 corresponding to a particular 1st selector control circuit and normally serving a particular group of 1st finders. If the 1st control circuit is available Ear is not energized and Hsr, Bsr follow Csr to energize the power magnets in series with Sgr which if any of these circuits is effective cuts off Abr before it can pull up. If however all the finders in the sub-group are busy, Abr pulls up after a short interval and extends the starting circuit to the next subgroup. If the control circuit is busy, Ecr is energized to cut off Hsr and Csr thus energizes Abr whether there are idle finders or not. One or more sub-groups, say the last, may comprise (say) 12 finders, the additional 2 being associated with a surplus control circuit which also serves the additional finders in the last sub-groups of all the other main groups. The off-normal relay 2Ecr of this control circuit has a slave relay Ecr1 which controls relays such as Hsr1 in each of the last sub-groups. When the starting circuit is extended to this sub-group or if a 1st finder to which this sub-group is first choice finds a line and energizes 1Csr, either, neither, or both the relays 1Hsr, Hsr1 pull up, depending on the condition of the control circuits, to energize the power magnets. If both control circuits or all 12 finders are busy, 1Abr extends the starting circuit to the 1st sub-group. When there are no finders available in the group, lamp SGL glows. The relays Hsr, Bsr in addition to energizing the power magnets PL, connect up the test relays Asr. This is to prevent a finder which is resting on the calling 1st finder terminals from switching through if it is not in the right subgroup. When the calling finder is found, 3Ar in the 2nd finder energizes 3Cr which shunts out Csr by the holding winding of 3Ar and energizes release relay 3Br, which is made slow to pull up to guard against a double test. 3Br energizes 3Dr which switches the loop through to 3Asr, and energizes 3Hr which energizes 3Ir and sends back ground over the c-wire to hold Lhr and energize cut off relay Cor. Association of idle register controller. 3Ir is followed by starting relays Ar, Br to energize the power magnets PM of the associating switches in all the idle register controllers. When the calling finder is found, Tr in the register-controller locks up over a low resistance winding in series with Shr, which is made slow to pull up to guard against a double test, and shunts out Ar. Shr energizes Er which sends back dialling tone from O via TO, the out-control wipers a, b, and the bridge condensers. Registration of number. 3Asr repeats the digits over Ir to Hr which repeats them to the registers SW1 - - SW4. Each of the 1st three registers on going off normal prepares a circuit which is completed on the relapse of Ir at the end of the digit for Jr, Lr, Or, respectively which switch over the impulse circuit to the next register. When the thousands register goes offnormal, Ur pulls up in series with 3Er, locks itself and 3Er and makes a new circuit for Er. 3Er cuts off dialling tone and releases 3Cr which releases Tr, Shr. Jr energizes Kr, Gr, the former locking up before Gr, which is sluggish, has opened its circuit. 1st selector, Fig. 4. The energization of Kr when the 1st digit has been received connects battery and ground to the a- and b-wires. Acr in the control circuit pulls up over the a-wire and energizes the power magnet PC to drive the marking switch. When the wiper i finds the calling selector, Bcr stops the switch and energizes J1r in series with For to associate the selector with the control circuit. J1r locks itself and Fcr to the c-wire, and Dcr pulls up over the b-wire in series with out-stepping relay Pr which energizes Rr. Rr energizes Sr, Nr, and if the register is not in position 10, 1Rr, and puts Pr across the a- and b-wires of the fundamental circuit. 1Rr holds Rr independently of Pr, and Nr locks up and releases Kr. Dcr re-energizes the power magnet PC of the marking switch, which in passing the long g terminals occupying the two middle positions of the four allotted to each group grounds the b-wire of the fundamental circuit to hold Dcr and short-circuit Pr which repeats the impulses to Qr to count out the register. Qr locks up over the interrupter on the register magnet to ensure a full step. When the register reaches position 10, 1Rr is released and on the next relapse of Pr, Rr opens the fundamental circuit and causes the sluggish relapse of Sr, Nr in succession. In the interval between their relapse, Qr, Mr, are energized in series over c (thousands) Er.1, and step the register to its home position and re-close the fundamental circuit respectively. Pr then pulls up again and holds Mr. Had the register been dialled to position 10 Rr1 would not have been energized and Rr would have fallen on the first relapse of Pr. When the fundamental circuit is opened, Dcr falls and energizes Gcr which locks, stops the marker, connects up the test relay Hcr which is now connected via wiper f to the multipled t terminals of the wanted group in the selector bank, and energizes PJ to drive the selector. When an idle 2nd selector with its control circuit idle is reached, Her stops the selector, shunts its high resistance winding by its low resistance winding in series with Scr which is made sluggish to guard against a double test and which energizes the switching relay J2r. J1r then frees the control circuit. 2nd selector (not shown). When J2r pulls up, Pr unlocks Mr, and if or when the hundreds digit has been recorded, Kr is re-operated over Fr.6, Lr.6, b (on hundreds register), Mr.1, Nr.1, Er.1 and again connects battery to the a-wire to operate a relay such as Acr in the 2nd selector control circuit. The 2nd selector is controlled in the same way as the 1st. Connector, Fig. 6. On the relapse of Mr or when the units register goes off-normal, whichever happens last, Kr is re-energized over the b wipers on the tens and units registers and energizes 9Acr which energizes 9Ecr and the power magnet 9PC of the control switch which is stopped on the calling connector by 9Bcr. F1r then connects 9Dcr to the b-wire and Pr, Rr, 1Rr, Sr, Nr pull up in the register controller. ODcr re-energizes 9PC, and the marker advances sending back impulses in the same way as the group selectors to count out the tens register. This marker is arranged to make a completerotation, the g-terminals being engaged twice by their wiper and the e and f terminals, which occupy two levels each, one. The 1st long terminal shown is in the preliminary section of the bank and is not grounded until the switch reaches the 2nd long terminal when 9Fcr pulls up, locks itself and connects g to the b-wire to send the 1st impulse. When the tens register is. counted out, Pr, Rr, 1Rr, Sr, Nr fall back as-' before but Mr is not energized and Kr pulls up, provided IT is back, as soon as Nr falls back, and re-energizes Pr, Rr, 1Rr, Sr, Nr and then falls back again. The momentary opening of the fundamental circuit by Rr, releases 9Dcr which stops the marker on the terminals next beyond the group terminal i.e. on the last terminals of the group preceding the wanted one. Centring is looked after by terminals i which are engaged' before g leaves the long terminal. 9Dcr energizes Icr and 9Gcr w