Patent GB-168870-A (GB)
Abstract: 168,870. Relay Automatic Telephone Co., Ltd., Assignees of Betulander, G. A.). Sept. 8, 1920, [Convention date]. Exchange systems. - A call distributor, comprising a relay switching arrangement, has associated with it a switching device, preferably a relay, which divides the calls into two groups, (1) calls which have been switched into readiness for connection and await an idle outgoing line, and (2) calls coming in later, which are not prepared for connection until all the calls of the first group have been disposed of. When this occurs, subsequent calls are prevented from connection until all this second group has been dealt with, and so on. The invention is described as applied to relay switching arrangements for connecting a calling " A " operator to an order wire common to a. group of " A " operators. In the arrangement shown in Fig. 1, four " A " operators' speaking lines AL - - AL4 may be connected to the common order wire GL through the marking relays MR1 - - MR4. Assuming that two operators at lines AL1, AL2 depress their keys K1, K2 simultaneously, both the calling relays AR1, AR2 are energized over the circuit 1, and locked up over the winding of the switching relay OR, which responds and opens the operating circuits of the calling relays, thus preventing subsequent calls from being prepared. The energization of the relay AR1 is followed by the energization of the marking relay MR1, which connects the line AL1 to the order wire GL, and locks up in series with the controlling relay KR, which opens the circuit of the other marking relays. On the order wire GL becoming idle, relays AR1, MR1, and KR de-energize, but the relay KR is immediately re-energized in series with the marking relay MR2 (the circuit of which was prepared by the calling relay AR2), and the line AL<2> is connected to the order wire GL. When this call has been dealt with, the switching relay OR relapses and closes the circuits of the calling relays AR of any lines now desiring connection. The invention is illustrated in Fig. 2 as applied to a known arrangement for connecting a calling " A " operator to an idle one of a number of order wires GL1, GL2. On an operator making a call, say over the line AL1, if an order wire is idle, his calling relay AR1 is locked energized over an armature KG1 or KG2 of the. connecting relays GR1, GR2, and the corresponding marking relay MR1 is energized in series with the controlling relay KR, which causes the test relays PR to select the first idle order wire and energize the corresponding connecting relay GR. A circuit is thereby completed for the cutoff relay UR1, which connects the line AL1 to the idle order wire. The switching relay OR is short-circuit ed over an armature KG1 or KG2 as long as an order wire is idle, but when both are engaged the relay OR is energized in series with the calling relays AR of the lines which have obtained connection, and subsequent calls are prevented from being marked. On an order wire falling idle, however, the relay OR is again short-circuited, and any calls awaiting connection are prepared by the energization of the corresponding calling relays AR. In a modification of the arrangement shown in Fig. 2, the lines AL are divided into two sections in order to avoid too many series contacts in the marking relays MR. The switching relay OR and the test relays PR are common to both sections, but a controlling relay KR is provided for each section, these relays controlling the circuits of each other, so that calls marked simultaneously in the two sections cannot be dealt with at the same time. The short-circuiting contacts corresponding to armatures KG1, KG2 are controlled by separate relays controlled by the connecting relays GR, and the contacts corresponding to the contacts K1 of the relays MR are arranged to be closed by separate relays, the winding of which are connected in series with the windings of the relays MR.