This document provides a comprehensive overview of the International Standard IEC 255-22-2, Second Edition (1996-09), which specifies electrostatic discharge (ESD) tests for electrical measuring relays and protection equipment. The primary objective of this standard is to establish a common, reproducible basis for evaluating the performance of this equipment when subjected to ESD, such as those that may occur during operation or handling.

The core purpose of the tests is to confirm that the equipment under test (EUT) will not maloperate when energized and exposed to an electrostatic discharge. The standard defines the test voltage levels, generator characteristics, test set-up, test procedures, and acceptance criteria. It outlines two primary test methods—contact discharge and air discharge—with contact discharge being the preferred method for its higher reproducibility.

Key specifications include five test severity classes (0 to 4) with test voltages ranging from 2 kV to 15 kV. Class 3 (8 kV contact, 15 kV air) is identified as the normal severity class for protection equipment. The standard meticulously defines the discharge generator’s parameters, including a 150 pF energy storage capacitor and a 330 Ω discharge resistor, to simulate a discharge from a human body. Acceptance is based on the EUT not exhibiting any incorrect operation during the test and meeting its performance specifications afterward; transient phenomena, such as a flickering LED, are tolerated.