IEEE C62.33

Abstract

This standard applies to varistors for surge protective applications on systems with dc to 420 Hz frequency and voltages equal to or less than 1000 V rms, or 1200 V dc. This standard contains definitions, service conditions and a series of test criteria for determining the electrical characteristics of these varistors. If the characteristics differ with the direction of conduction, then the tests determine characteristics for both polarities. Arresters covered by ANSI/IEEE C62.1-1984 [1]¹ are excluded from this standard. <br>The tests in this standard are intended as design tests as defined in ANSI/IEEE Std 100-1984 [3] and provide a means of comparison among various surge-protective devices. <br>Varistor surge-protective devices are used to provide transient overvoltage protection in electrical circuits. Varistors, as defined in ANSI/IEEE Std 100-1984 [3], are devices exhibiting a nonlinear volt-ampere characteristic. More specifically, this standard applies to such devices having a monotonic increase in voltage with increasing current flow. Because the impedance of the device decreases with increasing voltage, it provides a relatively low impedance path for surge voltages and a relatively high impedance at normal system voltage, before and after the occurrence of the surge. <br>Test criteria and definitions in this standard provide a common engineering language beneficial to user and manufacturer of surge-protective varistor devices. <br>Due to the voltage and energy levels employed in the majority of tests described herein, all tests should be considered hazardous and appropriate caution should be taken in their performance. <br>¹The numbers in brackets correspond to the standards listed in the Bibliography, Section 7. of this standard.