GB203129A - Improvements in control circuits, particularly for use in automatic telephone systems - Google Patents

Abstract

203,129. Western Electric Co., Ltd., (Western Electric Co., Inc.). July 13, 1922. Automatic exchange systems.-In order to ensure that the correct selecting operations are effected by impulses which, owing to their transmission over a long line or to a faulty sender, have become of unequal duration, the impulseresponding relay is provided, in addition to its operating winding, with a second winding so connected that, when the relay is energized, current in the second winding is opposed to that in the operating winding so that the relay is quick to deenergize, whilst, during de-energization corresponding to each impulse, current flows through the second winding in the opposite direction so that, at the end of the impulse. the relay is quick to energize. In the system shown, a line relay 2, responding to impulses transmitted from a substation dial 3, controls a register-mechanism 10. When a call is initiated, relay 2 operates over its right-hand (operating) winding, energizes a slowrelease relay 5 and completes a circuit through its left-hand winding, current in which opposes that in the right-hand winding so that, at the first impulse received, the relay is quick to de-energize. The relapse of relay 2 energizes stepping magnet 8 and completes a circuit from its grounded back contact over contacts 15, 16 and through its own left-hand winding in series with relay 5, the current in this circuit whilst insufficient in itself to energize relay 2 being in the direction to assist the operating winding, to ensure quick operation as soon as contacts 13, 14 are again closed. This circuit also serves to maintain relay 5 energized in the event of an exceptionally long impulse, and to short-circuit the operating winding of relay 2 to prevent further energization of the relay, in the event of an exceptionally short impulse, until after the magnet 8 has fully operated. At the end of its forward stroke, magnet 8 opens contacts 15, 16 removing the short-circuit from relay 2 which is thus ready to respond to the next impulse.