GB725230A - Improvements in or relating to electrical switching systems, particularly for electrical heaters on railway or like vehicles - Google Patents

Abstract

725,230. Switching systems for heating resistors. BREDA ELETTROMECCANICA E LOCOMOTIVE SOC. PER AZIONI. June 12, 1953 [June 14, 1952], No. 16304/53. Class 38 (4). In an electric vehicle intended for operating on tracks of different voltages and wherein the carriage heating resistors such as R, R<SP>1</SP> (with or without thermostatic control by a device E) are directly energized from the track conductor AT, the resistors are divided into sections r1, r2, r<SP>1</SP>1 R<SP>1</SP>2 which are respectively paralleled to bus-bars S1-S5 running throughout the length of the carriage and a voltage responsive switching system automatically causes such bus-bars to be energized as will result in the appropriate combination of the sections of each resistor to render it suitable for supply by the track voltage obtaining. The switching system comprises contactors C1-C6 having operating coils b1-b6 controlled by relays RL1, RL2 energized in series with the winding Rt of a time delay relay from the conductor AT over a rectifier Vu and resistor Rd. The relays RL1, RL2, which are one less in number than the number of different track voltages, operate, respectively, at the upper limit of each track voltage. The delay relay Rt prevents undesired interconnections by the contactors C1-C6 during transition from one track voltage to another.