Abstract: In a tunnel control system for traction vehicles, the normal deration function is suppressed to delay deration in a tunnel. The traction vehicle is provided with a controller having a normal operation mode and a tunnel operation mode. A tunnel indicator connected to the controller provides an indication of when the vehicle is approaching a tunnel and causes the controller to switch into the tunnel operation mode. In this mode, the controller increases cooling to reduce the temperature of the vehicle's prime mover and the control electronics prior to entering the tunnel. As the traction vehicle enters the tunnel, the controller monitors the engine oil temperature and the ambient air temperature. If the ambient air temperature exceeds a predetermined value, then the cooling of the control electronics is discontinued. If the oil temperature exceeds a threshold (which is about 10.degree. C. higher than the normal deration threshold), then power to the prime mover is derated.

Abstract: In an electrical propulsion system on board a moving traction vehicle (such as a rapid transit rail car) having current collectors in contact with an energized third rail, controllable switch means is used to connect the system to the current collectors. From time to time the current collectors traverse gaps between adjacent sections of the third rail, in which event regenerative braking operation of the system will be prevented unless the next third rail section is energized by a wayside source of voltage. The switch means comprises the parallel combination of a diode that conducts current when the system is operating in a motoring mode and a reversely-poled thyristor that conducts regenerative braking current once a firing signal is applied thereto.

Abstract: A plurality of high power semiconductor devices are connected in circuit with at least one electric traction motor for controlling electric power to the motor. The semiconductor devices are each thermally connected between a pair of generally hollow heat sinks adapted for passing cooling air therethrough for extracting heat therefrom. An anode terminal of the devices is coupled to one of the heat sinks of a pair and a cathode terminal of the devices is connected to the other heat sink of the pair. Each of the heat sinks are mounted in a cantilever fashion to a common air plenum forming one wall of an electrical circuit area of a vehicle. The distal ends of the heat sinks of a pair are coupled together by an air flow conduit thus forming a continuous air passage through the pair of heat sinks which begins and ends at the surface containing the air supply plenum. One end of one of the pair of heat sinks, preferably the heat sink coupled to the cathode terminal, is connected to an exhaust conduit.

Abstract: An improved auto-sequential commutated controlled current inverter for driving a multi-phase load from a source of controlled magnitude direct current is disclosed. The auto-sequential commutated inverter comprises a plurality of parallel connected branch sub-circuits with each branch sub-circuit comprising at least one gate controlled power thyristor device connected in series circuit relationship with a respective power diode. The branch sub-circuits thus comprised are connected between a respective phase input to the multi-phase load and a common direct current power supply terminal for connection to the source of controlled magnitude direct current. A respective commutating capacitor is interconnected between the junctures of the power thyristor and power diode of each respective branch sub-circuit and the power thyristor and power diode of the next adjacent branch sub-circuit.