A device for closing and tripping on the case of direct current, preferably, the networks to high voltage.

摘要

760,608. Railway signalling systems. PINTSCH BAMAG AKT.-GES. Feb. 10, 1954, No. 3951/54. Class 105. [Also in Group XXXV] In an arrangement for controlling a relay e in dependence on the state of an "on-off" switching element a connected in series with the input terminals of a " passive " network across a high - voltage D.C. supply, the operating coil of the relay is connected to the output terminals of the network which includes at least one reactive impedance and is such that a change in state of the element results in at least a temporary change in the state of the relay and that any direct current path from the supply to the relay is of such high resistance that it does not by itself carry sufficient current to operate the relay. In Fig. 1 the network is constituted by a transformer b, d, the charging current of which when the switch a is closed, produces a current pulse in the secondary winding d to operate the relay e. Alternatively or additionally the relay e may be arranged to respond to the voltage produced in the transformer secondary winding by the A.C. component, e.g. commutator ripple, of the supply. The flow of steady direct current through the primary winding b after the switch a has been closed may be reduced by providing a capacitor with parallel and series connected resistors in series with the primary winding b, Fig. 2 (not shown), and the resulting circuit may be tuned to the ripple frequency. The output of the secondary winding may be rectified and used to charge a capacitor to which the relay is connected, Fig. 4 (not shown). In a further arrangement, Fig. 5 (not shown), the coil of the relay is connected in series with the secondary winding d and an opposing secondary winding of a further normally energized transformer, the relay e being de-energized when the switch a is closed. Figs. 6 and 7 (not shown) illustrate the use of tapped impedances in place of the transformer. The switching element a may comprise the pantograph of an electric train which cooperates with an overhead current-carrying conductor and a parallel short length of conductor connected to the " passive " network. Alternatively, the element may comprise collector shoes and a conductor rail.