Westinghouse Electric Corporation

Siemens Westinghouse Power Corporation

John T Gordon

Jeffrey T Dederer

Michael A Cross

Stephen E Veyo

Larry A Shockling

An apparatus and method are disclosed for eliminating the chemical energy of fuel remaining in a fuel cell generator when the electrical power output of the fuel cell generator is terminated. During a generator shut down condition, electrically resistive elements are automatically connected across the fuel cell generator terminals in order to draw current, thereby depleting the fuel inventory in the generator. The invention provides a safety function in eliminating the fuel energy, and also provides protection to the fuel cell stack by eliminating overheating.

Fuel cell generator energy dissipator

A heater control circuit functions in conjunction with a suitable heating coil to provide precision, automatic temperature regulation. The combination of heating and temperature sensing functions into a single system results in a two-wire heater regulator control circuit in which a continuous excitation voltage and a power voltage can be simultaneously present at the heater coil. Temperature of the heater is established by continuous excitation and sensing independent of the occurrence of power for heating. A short circuit protection circuit is responsive to an electrical short in the heater coil (which significantly changes its resistance with temperature) and disables the power voltage.

Two wire heater regulator control circuit having continuous temperature

A low-level voltage clamp circuit drives its active components with the fault voltage of a main circuit being protected which main circuit operates at about one volt DC or less. The clamping circuit senses voltages in excess of a predetermined limit and effects the sinking of increasing levels of fault current in order to hold the voltage of the main circuit at the predetermined clamp limit.

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Ambridge, PA, United States of America

John T Gordon