Abstract: A fuel cell system for powering a work load includes a fuel cell stack and a shunt regulator having a threshold detection; transistorized power switching element, and a dump load. The threshold detection element identifies when an abnormally high voltage rises. The power switching element routes power from the high voltage buss to the dump load. The dump load acts as an electrical energy sink, and may provide dissipated energy to the fuel cell stack in the form of heat. The switching element can also shunt power to the dump load when a digital control signal is set, for example at startup or during cold start conditions.

Abstract: In a hydrogen gas line where the composition of the gas is primarily hydrogen, impurities present in the gas line will typically reduce the speed of sound. Accordingly, an acoustic sensor can be used in such a hydrogen gas line to indicate when impurities have accumulated in the gas line. In particular, the hydrogen gas line may be in a fuel line for an electrochemical fuel cell system. The sensor may comprise transducers, more particularly piezoelectric transducers, as both sound detectors and/or sound generators. Further, the sensor can measure either the speed or frequency of sound to determine the hydrogen concentration. If the fuel is recirculated back to the anode inlet, such a hydrogen sensor in the anode exhaust may be used to determine when it is beneficial to purge the anode exhaust to the external atmosphere.

Abstract: An apparatus for controlling a power distribution to devices has a power inlet to be connected to a power source, a primary power outlet to be connected to a primary device, at least one secondary power outlet to be connected to at least one secondary device, a sensing unit for sensing when a current level falls below a threshold in response to the primary device being turned off and when the current level raises above a threshold in response to the primary device being turned on, and an executing unit operatively connected with the sensing unit and operative for interrupting a power supply to the at least one secondary power outlet when the sensing means sense the current level below the threshold and supplying power to the at least one secondary power outlet when the sensing means sense the current level above the threshold correspondingly, the sensing unit being formed as a high frequency current sensing coil.