High-voltage switch (also known as high-voltage circuit breaker) is the main power control equipment in substation, which has arc extinguishing characteristics. When the system runs normally, it can cut off the no-load and load currents of various electrical equipment connected to the line. When the system fails, the matching relay can quickly cut off the fault current to prevent the expansion of the accident scope. Therefore, the performance of high-voltage circuit breaker directly affects the safe operation of power system. In order to realize the control and protection functions, it is necessary to ensure the reliable operation characteristics of high-voltage circuit breaker.

Whether the high-voltage switch can act as a relay for the high-voltage circuit is judged by the test of its on-off time, and it is also the guarantee for the normal and safe operation of the switch.

In this paper, the off time of high voltage switch is measured. High-voltage switch tester is a high-performance electronic component composed of control microcomputer hardware and software with STC89C52 as the core, which constitutes the functional control unit of the instrument. The tested time is sent to STC89C52 chip for analysis and judgment, and the measured data is sent to the liquid crystal display at the data transmission port D7-D 14 of Economic and LCD 1602, and the qualified time of the switch can be flexibly set for judgment.

Fault display, qualified products are displayed with LED indicator light. Considering the number of outgoing and qualified switches.

This paper introduces the design process of high voltage switch off time tester in four parts. The first section briefly describes the development trend and test research of high voltage switchgear. The second part describes the system hardware design process, the third part describes the system software design process, and the last part describes the system debugging process.