Judgment of automatic three-phase reclosure based on natural vibration voltage comparison is put forward in this paper,according to the present fuzzy judgment and fault operation in the process of reclosure.

To accomplish a voltage comparator with very low threshold and high precision that is quite complex in the integrated circuit of single power supply,a new comparator with extraordinary low threshold is designed.

It introduces a method of constructing high precision voltage comparator with 312 bit A/D converter IC7107, to the effect and the V\%\-\{in\} comparing precision can reach to 0.

The discriminator circuit is mainly composed of an integrated voltage comparator, MAX921, and owns the characters of very low power and low operating voltage.

Based on the analysis of some phenomena observed when applying integrated circuit operational amplifier as voltage comparators, this paper tries to present some causes and find out a solution by further analysing the observed deviations from theories; thus to strengthen the relationship between theory and experiment and to improve students expereimental capabilitie

The controller of aiming control platform (ACP) is composed with AT98C2051, Voltage comparing circuit, electric bridge and digital potentiometer X9241.