BS EN 61643-331:2003

1 Scope
2 Normative references
3 Parametric terms, letter symbols and definitions
  3.1 Ratings
  3.2 Characteristics
  3.3 Circuit symbol
4 Service conditions
  4.1 Normal service conditions
  4.2 Abnormal service conditions
5 Basic function and MOV component description
6 Identification
  6.1 Generalities
  6.2 Functional and constructive characteristics
  6.3 Manufacturing inspections
7 Marking
8 Testing and measuring methods
  8.1 Standard design test criteria
  8.2 Test conditions
  8.3 Ratings
  8.4 Electrical characteristics
  8.5 Dependability
9 Fault and failure mode
  9.1 Degradation fault mode
  9.2 Fault-mode determination of rating test failures
Annex A (normative) MOV testing for IEC 61643-1 surge
        protective devices
Annex ZA (normative) Normative references to international
         publications with their corresponding European
         publications
Bibliography
Figures

Designed to protect apparatus or personnel, or both, from high transient voltages. Applies to MOVs having two electrodes.

Details the test specifications for metal oxide varistors (MOV), which are used for applications up to 1000 V a.c. or 1500 V d.c. in power line, or telecommunication, or signalling circuits. The MOVs are designed to protect apparatus or personnel, or both from high transient voltages. Does not deal with hybrid devices. Does not apply also to mountings and their effect on the MOVs characteristics.