IEC 61643-331 pdf download Components for low-voltage surge protective devices – Part 331: Specification for metal oxide varistors (MOV) 1scope This part of lEC 61643 is a test specification for metal oxide varistors (MOV), which are usedfor applications up to 1 000 v a.c. or 1 500 V d.c. in power line,or ‘telecommunication，orsignalling circuits. They are designed to protect apparatus...