Patent ID: 7901821

Claim:
A method for shutting down an electricity supply system comprising a fuel cell, the cell being supplied with pure oxygen as the combustive gas and delivering an electric voltage to an electric power line, the system comprising: a fuel gas feed circuit on an anode side; an oxygen feed circuit on a cathode side; in the fuel gas feed circuit on the anode side, a feed valve and a pressure sensor fitted downstream from the feed valve; in the oxygen gas feed circuit, a feed valve and a pressure sensor fitted downstream from the feed valve, and a purge valve which enables the said oxygen feed circuit to be opened to the atmosphere; and a voltage measurement device in the said electric power line; wherein the shutting down method comprises the following stages: an initial stage during which the oxygen supply is interrupted; a consumption phase during which a sustained current is drawn off from the fuel cell; a neutralisation stage during which the oxygen feed circuit is opened to the atmosphere; and a final stage, during which the fuel gas supply is interrupted, wherein the initial stage enables the oxygen feed valve to be closed; the consumption phase takes place at least so long as the voltage is higher than a predetermined threshold value; and the neutralisation stage begins when the pressure in the oxygen circuit is lower than a comparison pressure and takes place as long as the voltage in the electric power line is higher than the said threshold value.