Magnetically controlled thyristor chopper for Seikan undersea tunnel battery locomotive

We have developed thyristor chopper equipment which is controlled by magnetic phase shifters as the speed control equipment of a battery locomotive for the Seikan Undersea Tunnel. The main feature of this equipment is adoption of a balanced half-wave type magnetic phase shifter, having high reliability together with many functions, in a simple structure to the thyristor gate control. Special consideration was given to the smooth control characteristics at around the minimum and maximum points of the chopper output voltage. This construction of equipment received special consideration regarding its ability to withstand severe working conditions. Satisfactory results were obtained in various performance and reliability tests, and locomotives supplied with this equipment are already operating in excellent condition.