This part of IEC 60255 is based on IEC 61000‑4‑5, referring to that publication where applicable, and specifies the general requirements for surge immunity tests for measuring relays and protection equipment for power system protection, including the control, monitoring and process interface equipment used with those systems.

The objective of the tests is to confirm that the equipment under test will operate correctly when energized and subjected to high-energy disturbances on the power and interconnection lines, caused by surge voltages from switching and lightning effects.

This standard does not intend to test the capability of the insulation to withstand high-voltage stress. The insulation test is covered by IEC 60255‑27.

The requirements specified in this standard are applicable to measuring relays and protection equipment in a new condition and all tests specified are type tests only.

The object of this standard is to define: