Detecting System of Voltage and Reactance LI Ji-ming, ZHANG Yue (Graduate School of ShenZhen, Tsinghua University ShenZhen 518055) Abstract: The Detecting System of Voltage and Reactance of electrical gears is designed. The system generates 1KHz sine wave using DSS method; amplifies the peak voltage of the stimulating sine wave and enhances the input resistance of the open voltage detecting module for the special requirements in the concrete evaluation; retrieves the voltage values digitally using ADC; gets the phase difference parameter digitally; utilizes PIC microprocessor as the main controller to time the detections, do the mathematic operations and display the outputs. Keywords: PIC Microprocessor; Voltage Detection; Reactance Detection; DSS