Power for high voltage monitoring devices cannot be supplied through secondary side directly because of the requirement of insulation.Hence

technique for obtaining power with stability and sufficient working time through primary side is necessary.On the basis of obtaining energy via electromagnetic induction of current transformer

single chip C8051F021 is adopted to construct a control circuit for improving the adaptability of a power supply

and thus achieving its stability and sufficient working time.The power capture module

over-current protection module and backup power supply module are controlled by the single chip through signal sampling to realize reliable over-current protection and power capture in wide variation of current and in low current.Simulation indicates that this design scheme of power supply is feasible.