Patent GB-391907-A (GB)
Title: Improvements in or relating to routine testing equipment for telephone or like systems
IPC: H04Q1/20
Filed: 1931-12-23
Abstract: 391,907. Automatic exchange systems. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, and TANCRED, P. B., 61, Deane Road, Edge Lane, both in Liverpool. Dec. 23, 1931, No. 35591. [Class 40 (iv).] Routine-testing equipment comprises two Strowger-type switches which interact to apply in succession the various tests and also perform other incidental functions such as timing intervals and counting impulses. The apparatus shown in the drawings which should be arranged as indicated in Fig. 13 is designed for testing incoming selectors provided with two sets of wipers and is associated with the selectors in turn over access equipment similar to that described in Specification 373,177 and shown in part in Fig. 12. Leads -, +, Fig. 18, and lead P, Fig. 6, extend over the access equip-, ment to the incoming side of the selector under test, leads P1, P2, Fig. 6, extend to the two test wipers, lead RM to the rotary magnet, and lead RT to a relay which disconnects the selector from the incoming junction and marks the latter busy as described in Specification 357,186. The two lines,connected to the tenth contacts of the ninth levels of the incoming selectors are used as test lines and for this purpose are connected as shown in Fig. 12 over contacts of relays OA, OB so that they can be disconnected from the succeeding selectors and diverted into the routiner. The two Strowgertype switches TS, ATS, of .the routiner each have six wipers lettered respectively A .. F, G .. M, the ten levels of each wiper being shown separately across the drawing. For example; the bank marked 5K, Fig. 3, represents the fifth level of wiper K of switch ATS, the connections to the wiper shown on this bank being the same as those shown on bank' 1K (for wipers L, M, of ATS, the wiper connections are shown on banks 7L, 7M, Fig. 12). The arrangement throughout the operations is such that the successful result of any test advances the switches into position for the next test, failure of the switches to advance within a given time causing the operation of an alarm. Detailed operation of complete test; level 1 of TS. Earth extended over the start lead, Fig. 18, from the access equipment operates relay TH which energizes vertical magnets tVM, aVM, to raise switches TS, ATS, to their first levels. Relays TS, AS operate over vertical-magnet contacts to transmit an impulse to the rotary magnets tRM, aRM. Relay PE operates over bank 1D and conductor 11 advancing TS to contact 2, relay PE being locked over the test wire of the first test line if the line is busy. When PE releases, relay AO operates over bank 1D marking the first test line busy and advancing TS to contact 3. Relay AO also energizes relay OA to divert the test line into the routiner. Relay PE then makes a similar test for the busy condition of the second test line and when idle, relay OS operates energizing OB which switches over the second test line and advances TS to contact 4 over lead 18. The locking circuit of PE is now extended to conductor P, Fig. 6, to test for the busy condition of the selector under test and when PE releases, switch TS moves to contact 5 in which relay TJ operates and switches over from a 3-minute delayed alarm to a 9-second delayed alarm. The selector under test is now marked busy by earth over relay PG, Fig. 5, which operates relay P. Relay WB operates over bank ID to advance TS to contact 6 in which WB is connected in a bridge connection over banks 1E, 1F, to the incoming talking conductors of the selector under test to test for any potential irregularities. The release of WB advances TS to contact 7 and earth placed upon the test conductor by the operation of the selector line relav short-circuits PG to advance TS to contact 8 in which WB is disconnected. The release of the selector line relay removes earth from the test conductor permitting PG to reoperate and move TS to contact 9, in which resistances YA, YB are bridged across the line. The selector line relay should not operate in series with these resistances and in order to ensure that it does not operate even slowly a time interval is marked off by the movement of switch ATS from contact 1 to contact 9 over banks 1G, 1B, 1H. If at the end of this interval, relays PG, P are still energized, switch TS moves to contact 10 over banks 1A, 1J, resistance YA being now cut out so that the line relay should operate and release PG. Switch TS moves to eleventh contacts in which springs tS operate to energize the rotary-release magnet tRZ. When the rotary off-normal springs tNR1 close the vertical magnet tVM receives an impulse and relay TS is then operated to advance the wipers to contact 1 in level 2. From contact 9, switch ATS steps to contacts 11 over bank 1G and is then released rotarily and set to the beginning of level 2 in a similar manner. Levels 2 and 3 of TS. Relay SG operates over wipers 2H, 2B when springs MPS next open and extends these springs over bank 2G to relay AS. At the same time a short-circuit is removed from loop springs LPS so that the switch ATS and the selector under test are stepped in synchronism the former to its 10th contacts and the latter to its 9th level. Resistance 25 renders the impulsing circuit similar to that over a short line. Earth over the 10th contact of bank 2K moves TS to contact 2 in which SG operates again and connects springs MPS over lead 30 to multiple terminals in banks 2A, 3A. Switch TS is thus stepped to contact 5 in level 3 in order to mark off a suitable time interval for the hunting operation of the selector under test. During this interval the selector is held over relay DD, Fig. 11, lead 53, and bank 2L, and the test wiper P2 is earthed over vertical wiper VB, Fig. 6, so that testing occurs only over the upper set of wipers. If an all-trunks-busy condition is encountered, simplex battery sent back operates alarm relay AM, Fig. 15. Normally, however, an idle trunk is seized, and if AM is not operated when TS reaches contact 5 in level 3, a further circuit is completed over lead 32 and bank 3A for moving TS to contact 6. Earth applied to wiper P1 now drives TS to contact 7 and PE operates to drive further to contact 8. In this position, switch ATS is driven to position 11 over bank 3D and thence is released rotarily and stepped to position 1 of level 3. The selector under test releases and when earth is removed from conductor P, relay PE releases and switch TS moves to contact 1 of level 4. If the guarding earth on conductor P is momentarily removed during impulsing, relays, PG, P operate, removing a short-circuit from relay ZT, Fig. 6, which energizes alarm relay AM. Levels 4 and 5 of TS. Relay SG operates over bank 4D and nine impulses are transmitted as before to ATS and the selector under test, resistance 25 being cut out to simulate zero-line impulsing. During stepping, switch TS moves to contact 2 and, when SG releases in position 10 of ATS, the latter moves to contact 4 of level 1 and drives TS to contact 3. The selector now hunts under the control of the lower test wiper P2, and the switch TS moves to contact 6 of level 5 to mark off a hunting period as before, and thence to contact 1 of level 6 in a manner similar to that described in the previous paragraph. Level 6 of TS. The selector is set to the 9th level as before but under long-line conditions. During hunting both test wipers are earthed until the tenth contacts connected to the test lines are reached. The number of hunting steps taken are counted by switch TS which is set one step for every two hunting steps under the control of a counting chain PA .. PC, Fig. 6, operated over lead RM. A rectifier MR1 prevents faulty operation of the rotary magnet by surges from the counting chain. After 10 steps, relay LL operates over bank 6D stepping TS to contact 10, and earth is removed from the test wipers and test lines so that the first test line is seized. By the time that LL releases, relay LA, Fig. 11, should be operated over the test line, indicating that the selector has switched through, so that switch ATS moves to contact 1 of level 6 and then holds the selector by earthing the negative wire whilst TS releases rotarily and then moves to level 7. Level 7 of TS. Earth over banks 7B, 6H, 6G drives ATS to contact 2 of level 6 and AS then moves to contact 2 of level 7 over bank 6J. Over banks 6H, 7B, ringing current is connected to the negative wire of the test line and if this is continuous, relay AC, Fig. 17, provided with a shunt rectifier MR2, responds to move TS to contact 3. In this position relay AC is connected to the positive line and, if the bridge impedance of the selector is correct, releases to move TS to contact 4. The continuity of the positive wire is then similarly tested and TS moves to contact 5 whilst ATS is driven to contact 3 and then automatically to contact 1 of level 7. Relay DD is bridged across the selector over bank 7F and moves TS to contact 6 in which the right-hand differential winding of DD is connected up and if the battery and earth connections of the selector are correct relay DD releases and moves TS to contact 7. Relay D operates to reverse the connections over relay LA and if this reversal is repeated back through the selector, relay DD operates again and drives TS to contact 8. Relay RT, Fig. 10, operates and energizes RG, Fig. 5, which connects springs 20PPS to the counting chain PA .. PC. Relay RG locks over conductor P and switch ATS is stepped over its seventh level to test the release time of the selector, stopping when earth is removed from conductor P. If the release time is too short, the switch stops in positions 2 .. 5 and a " fast lamp is lit over bank 7L or 7M, Fig. 12. Similarly, if too long, a " slow "lamp is lit. If correct, ATS stops in positions 6 .. 9 and drives TS to contact 9 over conductor 51. Switches TS, ATS then both move to level 8. Level 8 of TS. The selector is set to the 9th level as before but with a bridged high r