Zinc oxide surge arrestors include a column of zinc oxide varistor semiconductor ceramics which are completely insulated in the normal state of network and they become conductive in case of passage of excessive voltage. Zinc oxide varistors are semiconductor ceramics with excellent nonlinear electrical properties due to the grain boundaries and their microstructure. Theoretically finer granules with a narrow size distribution give better electrical properties. Electrical properties depend on the size and morphology of granules. In this research the effects of organic binder on grading distribution of granules and electrical properties of ZnO varistors were investigated. Results show that application of optimum organic binder leads to the production of granule with an appropriate grading distribution which consequently leads to the improvement of pressing, increase of density and strength of varistor and thus improves the electrical properties of surge arrester such as decrease of leakage current by 75%.
Fahimeh abedsaeedi1, Ehsan Kousha2
1- Barghgir Toos Company
2- Barghgir Toos Company
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