The invention relates to a protective device for an electric
system. The protective device for the electric
system comprises a
delay type open circuit protective circuit, a
negative temperature coefficient, a
control switch and a rapid open circuit protective circuit, wherein the
delay type open circuit protective circuit is used for carrying out open
circuit protection on a circuit when the electric
system has a short-circuit fault, and cannot carry out false operation on instant surge current of the electric system when the electric system is started normally, the
negative temperature coefficient is used for restraining the surge current brought by charging of the capacitive load at the moment of starting, the
control switch is turned off at the moment of starting of the electric system, is turned on after the starting of the electric system is accomplished, and is used for improving the surge current and eliminating influence caused by the
negative temperature coefficient on conversion efficiency, and the rapid open circuit protective circuit can timely carry out operation to be opened when the electric system has the short-circuit fault, and enables the
peak value of short-circuit fault current to be effectively restrained through the negative
temperature coefficient. According to the protective device for the electric system, when a switch device has a short-circuit fault, the rapid open circuit protective circuit can also be timely opened to avoid
impact damage caused by the surge current to devices of other portions, the protective characteristic of a power utilization system is comprehensively improved, and the defects of an existing
electric power protective device are overcome.