Patent GB-394785-A (GB)
Title: A telegraph exchange system
IPC: H04L12/14
Filed: 1932-04-18
Abstract: 394,785. Exchange systems. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. April 18, 1932, No. 11057. Convention date, April 18, 1931. [Class 40 (iii).] A telegraph exchange is provided with a call-meter which takes account of the duration of the call and the value of the lines employed. The meter is controlled by a time switch which is set by impulses sent back from each further exchange to which the connection is extended, the values of the lines used being denoted by the numbers of impulses received. The impulses may be sent in separate groups as each exchange is reached, or all together on completion of the call. In a modification, metering is effected according to the duration of a single metering impulse ; and one of a pair of conductors is used for the dialling impulses while the other is used for the metering impulses. Making an exchange connection. A subscriber's line terminates at the home exchange in a receiving relay which controls armature erl, and in an armature controlled by sending relay ES1. When the subscriber makes a call, armature erl is reversed, preselector VW is set hunting in known manner for a free group selector GW, and relays C1, T pull up. A train of impulses is then dialled by the calling subscriber, so that armature erl energizes the impulse-relay winding A1(I) the required number of times. Armature 42al operates the lifting magnet H and lifts the group selector into the required decade, which corresponds to the next exchange to be connected. The circuit of rotary magnet D is prepared at 39k by the first lifting step, but does not operate till slow-release relay PI releases at the end of the dial train ; rotary magnet D then, in co-operation with relay AI, causes the wipers GWa, GWb, GWc to hunt for a free transmitter relay Ua, which found, the test relay windings P1(I, II) pull up. Relay C2 and consequently X2 pull up, energizing ES2 via 62er2. A call is thus sent to relay ES3, Fig. 4, of the next exchange, armature 73es3 energizes relay R3, and armature 72er3 consequently reverses and sends a restoring impulse over trunk line FL to the receiving relay ES2 of the previous exchange, where armature 59es2 energizes relay R2. Metering. The meter, controlled by relay Z, takes account of the duration of the call, the contacts ZS being closed intermittently at various frequencies ; and also of.the zone value of the call, the effective one of the contacts ZS being selected by the wiper ZW1 of the zoneindicator in response to impulses from the connected exchanges. Setting of zone-indicator. Relay U, Fig. 3, having pulled up, the zone-indicating impulses from exchange Ub, Fig. 4, are sent by the metering-impulse-sender Zg. When relay R3 pulls up, as described above, armature 81r3 cuts in relav C3 and armature 86c3 cuts in the rotary magnet DF and interrupter UL2, so that wiper F2 is stepped round until it reaches its last contact, which is disconnected at 83g by the self-holding winding G(II). At the same time the wiper F1 impulses the relay J a number of times representing the zone value of the line, and armature 71j sends on the impulses to relay ES2 and so through 59es2 to ZR, through 15zr to ZH, and through 19zh to DZW which steps the wiper ZW1 through the number of steps corresponding to the zone. value. A similar train of zoneselecting impulses is sent back from each added exchange. Time-metering.-The meter is operated by the magnet GZ step by step. When the connection has been completed, the called subscriber sends an answer-back signal such as two or three groups of five negative impulses so as to demagnetize the polarized and highlyretarded relay U. Relay Z pulls up via 12u, short-circuits E at 25z, and is thus itself cut off again at 13e ; during this time the first of the meter-operating impulses has been communicated to the meter magnet GZ via 2e and 3z. Subsequent meter-operating impulses are controlled by the time-switch wiper 20<11>S, which makes three revolutions per minute. At its first contact with stud 2 relay M pulls up, and through 21m relay N pulls up and locks ; E then pulls up through 23n, but Z is cut off at 14n. At each subsequent contact of wiper 20<11À>S with stud 1, relay F pulls up and energizes rotary magnet DZS for the time switch ZS ; the contacts ZS are then mechanically operated at different intervals and metering impulses thus pass at the selected intervals through wiper ZW1 to relay Z and so to the meteractuating magnet GZ. Relay X1 ensures that the time-switch shall be stepped round to zero, when its hold-on circuit is broken at zs2. Release.-On receipt of the clearing signal relays P1, C1 release ; rotary switch DZW is connected to interrupter UL1 through 17C1 and steps the zone selector ZW to zero ; while on closure of contact 34c1 the relay F and rotary magnet DZS co-operate to step the time switch ZS to zero.