Patent ID: 7924536

Claim:
A short circuit protection device installed in an alternator to control the field current produced by a field coil of said alternator, the short circuit protection device comprising: a trigger switch electrically connected to said field coil and operated in such a manner that turning on/off said trigger switch corresponds to pass/cut-off said field current; a sensor having a current input node and a current output node respectively and electrically connected to said trigger switch and grounding potential, said sensor passing said field current when said trigger switch is turned on; a boost circuit comprising an input end and an output end, said input end being electrically connected to the current input node of said sensor; when the potential at said input end rises, the potential at said output end rises; when the potential at said input end drops, the potential at said output end remains unchanged; and a shutoff device comprising an upper conduction end, a lower conduction end, and a control end, which are respectively and electrically connected to said trigger switch, grounding potential, and the output end of said boost circuit, when the potential at said control end reaches a predetermined critical potential, said upper conduction end is conducted with said lower conduction end so as to turn off said trigger switch.