IEC 61643-331:2017

FOREWORD
1 Scope
2 Normative references
3 Terms, definitions, symbols and abbreviated
  terms
4 Service conditions
5 Mechanical requirements and materials
6 General
7 Electrical requirements
8 Standard design test criteria
9 Nominal discharge current and limited current
  temporary overvoltage
Annex A (informative) - MOV testing according to
        IEC 61643-11:2011 - Surge protective devices
        for the Class I, II and III
Annex B (informative) - IEC 61051 Varistors for use
        in electronic equipment
Annex C (informative) - Accelerated endurance
        screening test
Annex D (informative) - Proposed test method for
        determination of mean time to failure (MTTF)
Bibliography

IEC 61643-331:2017 is a test specification for metal oxide varistors (MOV), which are used for applications up to 1 000 V AC or 1 500 V DC in power line, or telecommunication, or signalling circuits. They are designed to protect apparatus or personnel, or both, from high transient voltages. This specification applies to MOVs having two electrodes and hybrid overvoltage protection components. This specification also does not apply to mountings and their effect on the MOV’s characteristics. Characteristics given apply solely to the MOV mounted only in the ways described for the tests. This second edition cancels and replaces the first edition published in 2003. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) Update of the nominal varistor voltage test method;
b) Addition of thermally protected varistors – component symbol and test methods;
c) Addition of nominal discharge current – test methods;
d) Addition of voltage ratings for disc types (Table 1);
e) Addition of test currents for clamping voltage of disc types (Table 2);
f) Addition of typical voltage ratings of SMD types (Table 3); and
g) Addition of Limited current and temporary overvoltage tests for thermally protected varistors.
Keywords: metal oxide varistors (MOV), high transient voltages.