As an important component in the power system

circuit breakers have complete type test requirements

one of which is out-of-phase making and breaking tests. GB/T 1984—2014 and DL/T 402—2016 have detailed de-scriptions of the out-of-phase making and breaking tests of circuit breakers

and both describe the exemption condi-tions for OP1

which means"If the 5% Isccritical current test is not required

OP1 can be omitted."This criteria hasbeen used for 20 years

with the progress of circuit breakers breaking principle

arc extinguishing method and manu-facturing technology

this criteria has been unsuitable in actual use.This article analyzes the system operating condi-tions

out-of-phase making and breaking tests and related tests principles

current domestic standards

find out thereasons for the defects in the current exemption conditions and proposes another exemption condition for OP1.