Patent GB-364720-A (GB)
Title: Improvements in or relating to means for controlling the switching processes in telegraphic apparatus
IPC: H04L12/12
Filed: 1930-10-27
Abstract: 364,720. Telegraph exchange and traffic-control systems. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. Oct. 27, 1930, No. 32252. Convention date, Oct. 28, 1929. [Class 40 (iii).] The receiving apparatus is prepared for operation (by switching-in of the motor or of a concentrator-connection) by impulses longer than the telegraphic impulses but similar to the clearing impulses, the switching-in operation being adapted to prepare a circuit for the clearing relay A while the clearing operation transfers the connection to the switching-in relay- E. Current may be normally flowing in the idle state of the line and may be reversed during the operative condition. Preparing receiver for operation. A switching-in impulse sent with the transmitter key T at station S1, Fig. 1, energizes the sluggish relay R at station S2' and consequently the switching-in relay E and self-holding motorcontrol relay H. The latter switches in the motor M and (after an interval which may be determined by a switch operated centrifugally by the motor) a relay U whose armature u substitutes release relay A for the switching-in relay E. The next long impulse, therefore, energizes relay A and thus causes the restoration of all parts to the idle position shown. Relay R being a sluggish relay is unaffected by the message signals. The switching-in impulse must not be held on, however, after relay U has acted in the arrangement shown in Fig. 1. This restriction is avoided by the use of a condenser C in the arrangement shown in Fig. 2. Operation of concentrator. A long interruption sent with the subscriber's key T1, Fig. 2, or central-station key T2 de-energizes the slowrelease relay R momentarily, discharging the condenser C which at the end of the impulse recharges itself through the switching-in relay E. The energization of switching-magnet D through armature e steps the switch-arms a .. d, one step forward, and thereafter the arms are carried by the switching-magnet D and interrupter RU to hunt for a disengaged instrument-set ER2, sr2. When this is found a circuit is closed through the busying-magnet U, which marks itself busy by short-circuiting its high-resistance winding at u3, cuts off the switching-magnet at u4, puts the line through at u1, u2, and at u3 transfers the circuit of condenser C from the switching-in relay E to the switching-out relay A, in readiness for the clearing signal. The line-current being reversed by contacts u1, u2, polarized relay P operates through relay Q to cut in the subscriber's motor M and also gives a ringing signal; and resistance WD may be a relay having the same effect at the central station. Relay R is a slow-release relay unaffected by message impulses, but when a (long) clearing impulse is sent by interruption of the line at T1 or T2, relay R releases momentarily and the subsequent charging of condenser C through relay A causes the latter to pull up. Relay U is therefore cut out at a and the connection is consequently released. In order that the interruption at a may endure long enough for the selector switch to be stepped home, a relay H with armatures h1, h2, may be arranged to prolong the slow-release period of the relay A.