Patent GB-279063-A (GB)
Title: Improvements in or relating to testing arrangements for telephone systems
IPC: H04M3/32
Filed: 1927-10-01
Abstract: 279,063. Siemens & Halske Akt.-Ges. Oct. 15, 1926, [Convention date]. Automatic exchange systems.-A routine testing system is provided with means for automatically setting up test connections between pairs of subscribers' lines. Connection is first made from the testing apparatus to a pair of lines and then the testing apparatus automatically sends over one of the lines the impulse trains necessary to set up a connection to the other. In the 10000-line exchange system described, one subscriber's line in each 100-line group is allocated as a test line, these 100 test lines being connected in the banks of two " calling side " 50- point switches AW1, AW3, Fig. 1, and two similar " called-side " switches AW2. AW4. in such order that in each position of the calling- and called-side switches, which move in synchronism, a different pair of test lines is taken into use. The number transmitted by the relay impulse sender, Figs. 4 and 5. is determined by three tandem-pairs of 50-point switches ZW1 - - ZW6, Fig. 2, which advance synchronously with the switches AW1 - - AW4 and the contacts of which are so cross-connected to the sender counting relays over a distributing frame 1DF that in each position the number sent is that required for setting up a connection between the two lines connected up in the corresponding position of the switches AW1 - - AW4. The switches AW, ZW may be advanced automatically step-by-step to test successively all the pairs, or they may be caused to hunt for a marked pair. Provision is made in the switches ZW whereby the number sent may comprise a varying number of digits, The synchronism of the switches AW, ZW is tested in their 26th positions. The impulse sender and the switches AW1 - - AW4 may be located in the same or in different exchanges. The lines of a testing pair may also belong to different exchanges. Establishing connection between first test pair TN1, TN2, Fig. 1 : four digits sent from routine tester. A switch (not shown) is first operated to connect up the battery of the routine tester and close a bridge, 10, 116, 126, 115, 11 across a subscriber's line TN1, Fig. 1. to cause the line switch VW1 to seize an idle first selector IGW. Momentary depression of the starting key ANT, Fig. 2, then closes a circuit for relay C1 which locks up over its upper armature, de-energizes the normally energized relay N2, Fig. 5, and energizes relays K, R, Fig. 4, which lock up over armature 158 and energize start relay U. A circuit is now closed over lead 234 for counting relay I, Fig. 5, which locks to conductor 231 and energizes relay J, Fig. 4, over lead 230. Relay J opens the impulse loop at armature 126 and energizes relay A, which closes circuits for relay C and relay O (upper winding). Relay O shortcircuits impulse relay J. which removes a shortcircuit from the upper winding of relay B, which locks up over both windings in parallel with relay A and de-energizes relay 0. Relay O removes the short-circuit from relay J which again opens the impulse circuit and de-energizes relay A. thereby removing a short-circuit from the upper winding of a relay L, which then locks over both windings in parallel with relay C. Relay O is re-energized and short-circuits relav J. Relay A also unlocks relay B which de-energizes relay 0, thereby closing a circuit for relay II, Fig. 5. which locks up. At the same time relay J pulls up and sends a third impulse. The above cycle of operations is repeated to send a fourth impulse with the exception that when relay A relapses, relay L is unlocked to prepare the circuit of relay III which is energized on the next relapse of relay 0. This operation continues, the relays J and 0 interacting and the counting relays I - - V being energized in succession after each even impulse and relay B being de-energized during each odd impulse and energized during each even impulse. At each impulse a stop relay P is connected up over armatures 127. 123 to one of the conductors 100 or 101. It will be seen that two impulses may be sent between the energization of each two successive counting relays, each of which when energized earths one of five stop wires 108 - - 112 connected to five terminals on one side of the distributing frame 1DF, the terminals on the other side of which are connected to the banks of all the wipers of the switches ZW1. ZW4 and the first and second wipers of switches ZW2, ZW5, ZW3 ZW6. Conductors 100 - - 107 extend from these wipers to the impulse sending apparatus, a pair of conductors being used in the sending of each digit. The values of the digits are determined by the crossconnections at the frame 1DF. For example, if the first digit is an even one, for example, 6, the stop wire 110 is jumpered across the frame to a contact in the bank of the second wiper of the switch ZW1 connected to the right-hand lead 101 of the first pair. After the sending of the fourth impulse, counting relay III earths the wire 101 over the wire 110. At the fifth impulse, relay B being de-energized, the stop relay P is net connected up, but at the sixth impulse B is ener gized and relay P energizes in a circuit 127, 123, 101.110. If the first digit had been odd, for example 5, the conductor 110 would have been connected across the frame and the first wiper of the switch to the left-hand lead 100, over which relay P would have energized at the fifth impulse (when relay B is energized). Relay P lochs up in series with the lower winding of relay 0, energizes relay X, and unlocks start relay U which unlocks the counting relays I - - III. Relay I removes earth from locking conductor 230. Relay U short-circuits the lower winding of relay O, which after an interval relapses and short-circuits, the locking winding of relay P. Relay X energizes a switch-over relay T and locks up in series with relay Y which then locks over its lower winding in parallel with relay X. Relay T connects up the control conductor pair 102, 103, and on the relapse of relay P relay U again pulls up and starts the sending of the next digit. The second digit is sent in a similar manner to the first, and on the response of stop relay P, relays X and Y are unlocked and a circuit is closed over the bottom winding of relay II and the upper winding of relay T. Relay II connects up the control conductor pair 104, 105 in preparation for the third digit. In a similar manner conductors 106, 107 are connected up after the third digit by switch-over relay Z. After the transmission of the fourth digit, relay E is energized and closes a circuit for the lower opposing winding of relay R which falls away ,unlocks relay C1, and energizes the lower opposing winding of relay K. Relay K unlocks relays T. H, Z. E. The relapse of relay C1 lights lamp L1. Fig. 2, in series with relays P1 to indicate that the restoration of the sending apparatus has taken place. Sending apparatus transmits three digits only. In certain positions of the switches ZW1 - - ZW6. a relay D1 is energized which closes a circuit for relay E before any digits are sent. so that when three digits have been sent and relay Z is energized. the conductor pair 106, 107 is found disconnected and the opposing winding of relay R is energized to initiate the release of the sending apparatus. Alternative arrangements of relays similar to relay D1 are described for use when it is desired to suppress a digit, in various numbers of connections. Testing operations. The transmitted digits operate group selectors IGW. IIGW and a connector LW. Fig. 1, to extend connection to the line TN2 to which the testing apparatus is connected over switch AW2. The first period of ringing current energizes an alternating current relay L1, which energizes relay U1 which locks up and extends the ringing circuit over leads 12, 14 to relay R1, Fig. 2. Relay R1 energizes relay G, which closes a circuit for lamp L2 to indicate that the first ringing period has been sent. At the end of the first period relay R1 relapses and relay G locks up in series with relay F1 so that when relay R1 re-energizes during the next ringing period relay Q locks energized and lights a signal lamp L3. Relay Q at armature 40 puts a bridge across the called line including the upper winding of relay R1, which locks up, lights signal lamp L4 and energizes relay M1. Relay M1 at armatures 34, 35 opens the bridges across both subscribers 'lines and unlocks relay U1, Fig. 1. The metering current over the third wire c, Fig. 1, energizes relay B1 which locks up in series with relay Z1, Fig. 2, which lights signal lamp L5. Advance of switches AW, ZW to initiate successive tests. Relay Zl energizes relay F which at armatures 53, 51 respectively closes circuits for the stepping magnets D5 - - D7 of the switches ZW1 - - ZW3 and for relay S1, Fig. 1, which energizes the magnets D1, D2 of the switches AW1, AW2. When all the rotary magnets are operated, a chain circuit is closed over their armatures for relay N, Fig. 2, which deenergizes relays G, F1, Q, A1, M1, Z1, B1, and energizes relay S, which locks up, de-energizes relays N, S1, F causing the relapse of the rotary magnets, and at armature 49 closes a circuit for the first relay of a chain VI - - VIII, Fig. 3, which delays the next sending operation for a suitable period in the following manner. Relay C1, Fig. 2, is energized in series with relays VI, Fig. 3, but owing to the high resistance of the latter, relay C1 does not pull up. Relay VI closes a parallel circuit for relay VII which energizes relay VIII and removes a shunt from a resistance 250. Relay VIII short-circuits relay VI, but relay C1 does not operate yet, being in series with the resistance 250. Relay VI deenergizes relay VII which opens the circuit of relay VIII. In the interval between the relapse of relays VII, VIII. the relay VI and resistance 250 are both short-circuited, causing the response of relay C1 which starts the sending apparatus and