EMC testing is divided into electromagnetic interference (EMI) and electromagnetic sensitivity, namely anti-interference EMS. Electrostatic discharge immunity is a testing item in EMS, because when an object with static electricity is discharged, it will generate a discharge current, which will produce a brief and strong electromagnetic field. The brief discharge current and corresponding electromagnetic field generated during discharge may cause faults or even damage to the circuits of electrical and electronic equipment. The purpose of electrostatic discharge test is to test the performance of electrical and electronic equipment when subjected to such electrostatic discharge disturbances.

The electrostatic discharge test is mainly aimed at maintenance that users can implement. The areas and locations that users can access during normal use are divided into direct discharge and contact discharge. Direct discharge simulates the electrostatic discharge that occurs when operators come into direct contact with the tested equipment. Indirect discharge refers to the discharge of horizontal and vertical coupling plates, simulating the situation when operators discharge objects placed or installed near the test equipment. Contact discharge is a test method selected based on the product, while indirect discharge can only be used in situations where contact discharge cannot be used.

The layout of a typical laboratory is as follows: desktop equipment is placed on a table 0.8m above the reference level, and a 0.5mm insulation pad is used to separate the tested equipment and cables from the coupling plate. The distance between the tested equipment and each side of the coupling plate is not less than 0.1m. During the test, a discharge point is selected on the EUT, and then it is determined whether to choose contact discharge or air discharge at this point. Generally, the metal shell is used for contact discharge, the insulation shell is used for air discharge, and the metal shell with insulation layer needs to scrape the insulation layer for direct discharge. The number of discharges at each discharge point is not less than 10 times, with an interval of not less than 1 second between each discharge point.