Patent GB-740389-A (GB)
Title: Line testing circuits comprising automatic routiner
IPC: H04M3/30
Filed: 1953-05-01
Abstract: 740,389. Automatic exchange systems. WESTERN ELECTRIC CO., Inc. May 1, 1953 [May. 6, 1952 ; May 6, 1952], No. 12118/53. Class 40 (4). A routiner comprises an insulation-testing circuit for carrying out one of a number of different tests on all the lines in succession. The apparatus has nine keys whereby any of the following three tests may be made over different ranges of efficiency: (1) short and ring ground test, (2) tip and ring ground test, (3) foreign potential test. The control circuitseizes a group of five lines in one frame and after testing them seizes the corresponding group in the next frame and so on before testing the next group of lines in the first frame. If a line fails to pass either of tests (1) or (2) it is re-tested for off-hook or plug-up (i.e. out-ofservice) condition before signalling the recording device. The test circuit may be checked by a calibrating. circuit, potential dividers being adjustable in the valve circuits of the test circuit until the required indications are given by lamps in the calibration circuit. Short and ring ground test. Starting. This test may be started by operation of any one of keys 15-01, 15-21, 15-23 according to the resistance range desired. Operation of key 15-01 lights lamp 15-02 and energizes sleeve relay 15S1 which locks up, lights lamp 15L1, and operates short and ring ground relay 27SRG. 27SRG energizes 27SRG1- which causes 160N, 16ON1, 16ON2 and 160N3, to operate, so connecting power supply to the test circuit of Figs. 31, 32. 16ON delays testing until the tubes are in operating condition by closing a charging circuit for condenser 16-OC which when charged fires gas tube 16-O8 to operate start relay 16ST. 16ST locks up, quenches gas tube 16-O8 and operates line link controller check relay 28LLK. The marker associated with the line-insulation test control circuit is not seized until at least onemarker has been idle for 5-8 seconds, this interval being timedby gas tube 10-O1, when all markers busy relay 10AMB falls back. Release of 10AMB also operates seize marker relay 10SM. Tube 10-01 operates 10SMT which quenches the tube and energizes marker seizer relay 10MS. Operation of 16ON3 meanwhile energizes 16SK which puts resistance 16-16 into circuit to saturate the magnetic cores of a magnetic modulator 31-05 and starts a timing circuit comprising condenser 16-12 and tube 16-11 to operate 16 SKT which quenches the tube. Seizure of marker and line link connecter multiple. To gain access to subscribers' lines the line insulation test circuit uses the line link frame connecter of one of the non-special markers. Before the connector leads are transferred the associated marker is busied. The marker is restored .to. service and testing suspended if it is required for traffic or test calls. Relay 10MS locks up, busies the marker circuit. releases 10SM which restores 10SMT and operates frame delay relay 28FD to start a timing circuit comprising gas tube 28-02 and condenser 28-03, so that if the no-test connecter and line link frame are not seized within a certain time tube 28-02 fires and operates 28FDT to bring in an alarm. 10MS also causes 10MTT to operate if the marker is busy. 10MS also energizes 10TM1 to start a guard timing interval to enable a service call to record a marker busy condition if both the test control circuit and a marker connecter seize the marker at the same time. 10TM1 operates 10TM2 slowly to release 10TM1 slowly so that, if 10MTT has not operated to a marker busy condition, 10MC operates. 10MC operates cut-off relay 13CO1 which operates 11CO2-11CO5, 12CO6- 12CO9, 13CO10-13CO13 (Fig. 11, and Figs. 12-13, not shown) which cut off the leads of the line link frame connecter multiple from the marker and close a chain circuit to operate cutin relay 13CI1 (not shown) which operates cut-in relays such as 11CI2-11CI5 to connect the leads of the connecter multiple to the lineinsulation test control circuit and maintain 13CO1 (not shown) energized. A chain circuit over conductor 11-O1 operates marker connecter check relay 28MCK which locks up and prepares a circuit to 29LLC1. No-test connecter seizure. So that all lines including apparently busy lines can be tested, one vertical is reserved in each frame for a notest trunk. If the no-test connecter level is idle hold relay 19H is normal and resistance battery is connected over conductor 19-01 to the master test frame connecter which operates 19SPC in the test control circuit when preference is accorded that circuit. 19SPC operates 19F which energizes select magnets 20S0- 20S9 in the no-test connecter associated with the level used for the line insulation test control circuit. 19SPC also operates 14RON to enable the line link frame to be held busy for a time long enough to record any troubles which may be detected in the testing of a group of five lines. Line link frame seizure. Starting from line link frame O and line group O the control circuit progresses through the line link frames to connect to the lines of each line group. Off-normal relay 16ON operates the frame-tens zero, frame-units zero, vertical group zero and horizontal group zero relays 25FTO, 25FUO, 30VGO and 30HGO. 25FTO operates auxiliary relay 30FTAO. To check that only one relay in each group is operated and that the line link frame connecter is connected to the control circuit, 29LLC1 energizes to operate line link controller relay 29LLC. 29LLC restores 28LLK and energizes 4MP to obtain preference for the line link frame zero and energize 5MC1A, which energizes line link frame connecter relays 4MCA2, 5MCB1 when preference is given. 5MCA1 also operates 28LF which releases 28FD to disable the timing circuit 28-02, 28-03 and activates a similar timing circuit 28-06, 28-07 which, if it times out, operates 28LFT. 5MCA1 also energizes horizontal group relay 3HGO in the line link frame and vertical group relay 3VGBO in series with vertical group check relay 28VGK. 3HGO operates 28HGK which energizes 3LGO, the line group relay corresponding to the operated horizontal and vertical group relays. 3LGO connects five pairs of conductors for five subscribers' lines to the lineinsulation test control circuit. Channel testing and selecting. The sleeves of the ten line links associated with the horizontal group are now connected over the contacts of 3HGO and the lower armatures of corresponding channel relays 29CH0-29CH9 to test line link relays 29TLL0-29TLL9, these paths being established to select an idle line link.. 28HGK reverses polarized channel timing relay 28 CHT slowly to allow any of relays 29TLL0-29TLL9 corresponding to a busy line link to operate from ground on their sleeve conductors or for junctors busy relay 28JB to operate if the no-test junctor is busy. 28CHT operates 28CHTI. Assuming that the first line link is busy and that the second is idle so that 29TLL0 is operated and 29TLL1 is normal, then 29CH1 operates to prevent 29TLL1 operating when the associated line link is busied. 29CH1 connects the sleeve of the link being selected to double test relay 18DT which operates only if a busy line has been selected through failure of some relay or conductor. 29CH1 also operates select magnet 2LS1 of the selected link together with other select magnets' connected in multiple associated with the same link of the line link frame. Operation of no-test connecter. 29CH1 also operates hold magnet 20HO to close the crosspoints associated with all the select-magnets 20S0-20S9. 20HO also operates no-test hold magnet 2NT and four others in multiple corresponding to half the vertical file of ten hold magnets comprising the first. vertical file of group 2 assigned to the no-test connecter. 28CHTl extends ground from the cross-bar switch contacts of 20SO and 20HO to operate no-test advance relay 19NTA which locks up. 19NTA releases 19F to restore select magnets 20S0-20S9. 19NTA allows service of no-test calls from the markers but not from the master test frame as the common no-test connecter level is held busy. Subscriber line hold magnet timing. Select magnet 2LS1 and the other four in multiple remain operated during the testing of the five subscribers' lines in the group or until the frame is released due to detection of a line fault. To ensure that the select fingers have separated before the first subscriber's line hold magnet energizes, 29CH1 operates polarized magnet 28HMT slowly to energize 18LGS which locks up and energizes 17VFO. Test. for busy lines and verticals to be bypassed. 3LGO connects the line hold leads 3-O3 of the five associated lines and the vertical file conductor 3-O6 to the conductors 3-04, 3-07 of the control circuit. The sleeve ground maintaining the hold magnet of any busy line is thus extended to energize the corresponding busy test relay 17LBT0- 17LBT4, which operates the corresponding relay 17LB0-17LB4. Toll trunks and lines terminating at private branch exchanges are by-passed. The related conductor 3-O6 may be connected to resistance battery (not shown which operates a corresponding skip relay 17SKP0-17SKP4 which energizes the corresponding relay 17LB0-17LB4. Alternatively a graded service line to be by-passed applies ground (not shown) to a conductor such as 3-16 to operate the related relay 17V0-17V4 which energizes the associated relay 17LB0- 17LB4. Operation of line hold magnet of first subscriber in the line group. Assuming that none of 17VO, 17SKPO, 17LBTO is operated, 17LBO is normal so that 17VFO already energized by 18LGS remains operated and locks up. 18LGS also operates line hold transfer relay 19LHT which operates hold magnet 2LHO through a chain circuit associated with the relays 17VF0-17VF4. Since 2LSI is already operated the appropriate cross-point is closed to connect the party line having stations 2-11, 2-12 to link 1 of the horizontal group O. Steeve continuity through the cross-points involving 2LHO, 2NT, 29S1 and 20HO, 20SO is checked by operatio