Patent ID: 7442455

Claim:
An apparatus for protecting a fuel cell which generates electricity by supplying as reaction gases hydrogen to an anode and oxygen to a cathode for electrochemical reaction, the apparatus comprising: a hydrogen sensor for detecting hydrogen in off-gas discharged from the cathode; an operating state detecting unit separate and distinct from the hydrogen sensor, wherein the operating state detecting unit includes a pressure detector for detecting the pressure of the reaction gases supplied to the anode and the cathode, a flow rate detector for detecting the flow rate of the reaction gases supplied to the anode and the cathode and a current controller for detecting a generated current of the fuel cell; a memory unit for storing a determination threshold value which changes according to an operating state of the fuel cell during operation of the fuel cell, wherein the determination threshold value decreases when a loaded state of the fuel cell decreases; a control unit coupled to the operating state detecting unit, the control unit configured to determine an abnormal state of the fuel cell by comparing a detection value outputted from the hydrogen sensor and the determination threshold value obtained from the memory unit according to the detected operating state of the fuel cell and determining that the fuel cell is in the abnormal state if the detection value exceeds the determination threshold value, wherein the control unit determines the operating state of the fuel cell based on a plurality of detections supplied to the control unit by the operating state detecting unit, the detections comprising a detection of the pressure of the reaction gases supplied to the anode and the cathode, a detection of the flow rate of the reaction gases supplied to the anode and the cathode and a detection of the generated current of the fuel cell; and a protecting unit for changing the operating state of the fuel cell if the control unit determines that the fuel cell is in the abnormal state.