Patent ID: 7537847

Claim:
A fuel cell system comprising: a fuel cell which is supplied with a fuel gas and an oxidizing gas to generate electricity; a fuel gas supply interrupting device for interrupting said fuel gas supply to an anode inlet of said fuel cell; an anode-off gas interrupting device for interrupting an anode-off gas discharged from an anode outlet of said fuel cell; a diluter for reducing a hydrogen concentration of said anode-off gas discharged from said anode outlet; an oxidizing gas supply device for supplying said oxidizing gas to a cathode inlet of said fuel cell; and a cathode-off gas passage for introducing a cathode-off gas discharged from a cathode outlet of said fuel cell into said diluter, wherein when a problem occurs in said system, said fuel gas supply interrupting device cuts off said fuel gas supply to said anode inlet, while said anode-off gas interrupting device keeps said anode outlet open until a predetermined condition is satisfied following the occurrence of said system problem, and said oxidizing gas supply device introduces said cathode-off gas discharged from said cathode outlet into said diluter by supplying said oxidizing gas continuously to said cathode inlet while said anode outlet is open following the occurrence of said system problem.