MOA Metal Zinc Oxide Varistor Resistor Disc With KEMA For Surge Arrester

Introduction:

A varistor remains non-conductive as a shunt-mode device during normal operation when the voltage across it remains well below its "clamping voltage", thus varistors are typically used for suppressing line voltage surges. However, a varistor may not be able to successfully limit a very large surge from an event like a lightningstrike where the energy involved is many orders of magnitude greater than it can handle. Follow-through current resulting from a strike may generate excessive current that completely destroys the varistor. Lesser surges still degrade it, however. Degradation is defined by manufacturer's life-expectancy charts that relate current, time and number of transient pulses. The main parameter affecting varistor life expectancy is its energy (Joule) rating. As the energy rating increases, its life expectancy typically increases exponentially, the number of transient pulses that it can accommodate increases and the "clamping voltage" it provides during each transient decreases. The probability of catastrophic failure can be reduced by increasing the rating, either by using a single varistor of higher rating or by connecting more devices in parallel. A varistor is typically deemed to be fully degraded when its "clamping voltage" has changed by 10%. In this condition it is not visibly damaged and it remains functional (no catastrophic failure).

Specifications:

D28 Metal Oxide Varistor(MOV):

About us:

Yongde holds the quality policy of being 'the technical forerunner, supreme in quality, supremacy of customers, and innovative progressing', so that our products and services successfully satisfied our users. We warmly welcome friends and customers from home and abroad to contact for exchanges and corporations. We also welcome feedbacks from our user communities.