GB375804A - Improvements in a reverse current relay arrangement for use in electric rectifier installations - Google Patents

Abstract

375,804. Protective cut-out arrangements. LUTZ, F., 32, Sulgenauweg, Berne, Switzerland. March 25, 1931, No. 9110. [Class 38 (v).] A reverse - current relay arrangement for use with a rectifier has the relay winding in series with a valve connected across a shunt or other portion of the rectifier circuit so that on reversal of current in the rectifier due to back arcing current flows in the relay winding to produce an indicating or switching operation. As shown in Fig. 1, the relay winding B with current in the normal direction in the rectifier circuit, consisting of the anode A, transformer winding T, and shunt S, is fed only by a limited current through a resistance R. On reversal of current in the rectifier circuit, however, a substantial current is shunted to the winding B through the valve V, which current may be utilized to operate an indicator or circuit-breaker. The arrangement may be modified for polyphase circuits, Fig. 3 (not shown), in which the three valve elements may be combined. An alternative arrangement shown in Fig. 2 has the shunt S in the grid circuit of the valve W, the relay winding B being included in the anode circuit. Instead of a shunt, a choking coil, impedance or a tapped portion of the transformer winding, Fig. 4 (not shown), may be utilized for providing the current in the relay arrangement.