A dc power supply circuit connects a plurality of dc circuit breakers to a semi-conductor converter, returning again to the semi-conductor converter through a dc driving part such as an electric railcar connected to each dc circuit breaker. A second dc circuit breaker of larger capacity than the above-mentioned...http://www.google.es/patents/US5576580?utm_source=gb-gplus-sharePatente US5576580 - DC power supply circuit
