GB494582A - Improvements in or relating to telegraph switching systems - Google Patents

Abstract

494,582. Telegraph exchange systems. LORENZ AKT.-GES., C. April 23, 1937, No. 11683. Convention date, April 23, 1936. [Class 40 (iii)] In a telegraph automatic exchange system, faulty setting of the selectors by telegraphic signals is prevented by arranging that if a selector receives more than ten impulses the test circuit is opened and the partially-established connection is released. In the system shown, closure of the calling key AT, Fig. 1, operates relays E, R causing the preselector, Fig. 2, to rotate until an idle group selector, Fig. 3, is reacted. Test relay T operates in series with relay C (i) and energizes H. The operation of contact t2 reverses the direction of current over wire b<11> causing the operation of relays S, N which reverse the. current over the calling loop a<1>, b<1> causing relay P<1> to operate and start the motor Mo. Impulses from dial contacts nsi are repeated by relay E to relay I (i), Fig. 3, to operate the vertical magnet H'. At the end of the digit, relay P (iii) releases and hunting takes place under the interaction of rotary magnet D' and relay I (ii) until relay P (i) (ii) again operates over wiper c. If a train of more than ten impulses is received, originating, for example, at transmitting key SK, contacts ko operated at the 10th step switch the lead a<11> over to relay Y (i) which operates on the 11th impulse to open the circuit of test relay P and to reverse the current over wire b<11> so that relays S, N, P<1>, E, R, T, C and the group selector release and motor Mo is stopped.