Validating surge test standards by field experience: High-energy tests and varistor performance

High-energy surge tests emerging in IEEE and IEC standards are addressed. The results of modeling the application of a surge test to a family of commonly used varistor sizes (14, 20, and 32 mm in diameter) are reported. For each varistor size, the computations were performed for three levels of manufacturing tolerances on the varistor: nominal value, -10%, and +10%. It is concluded that a reexamination of the premises that led to the proposed IEC test specifications is necessary. The proposals in the new version of IEEE C62.41 appear more consistent with field experience