Department Of Electrical/Electronic Engineering Conference Presentations


INTRODUCTION


The production of lightning arresters using locally available materials in Nigeria was carried out Usifo and Edeko (1998). They used a mixture of haematite and calcium carbonate to produce the arrester. Usifo (2001) conducted s further work on these materials which resulted in the present day Oriaghe (named after the inventor) lightning arresters which have the same characteristics as that of the silicon carbide based lightning arrester. It would be interesting to note that these lightning arresters were the spark gap…
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INTRODUCTION
The protection of electrical appliances, installations and personnel against surge voltages resulting from lightning and switching of reactive loads is not new. Benjamin Franklin is a pioneer scientist in the study of lightning (Gupta, 2007). After his famous experiment of flying kite in thunder cloud in 1745, he proved then that lighting stroke is caused by the discharge of electricity. He invented lightning rods for fixation on tall building and grounding it for protection against lightning strokes.


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INTRODUCTION


Significant development has been made in the improvement of the electrical and mechanical properties of zinc oxide varistors since its discovery by Masuka in 1970 (Evbogbai, Ajuwa and Edeko, 2011). Zinc oxide varistors are produced by advanced ceramic sintering process that give rise to structure comprised of conductive ZnO grains surrounded by electrically insulating barriers. These barriers are derived from trap states at the grain boundaries induced by additive elements such as Bi, Co, Pr, Mn (Lagrange, 1991).…
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INTRODUCTION


Zinc oxide varistors are voltage dependent resistors which exhibits nonlinear current-voltage characteristics. The non ohmic property, current handling capability, transient energy absorption capability, response time and high nonlinear coefficient make it more suitable for voltage surge suppression. Varistors are produced by advance ceramics technology. Different kinds of techniques for its production are available elsewhere (Lagrange, 1991; Harris, 1999).


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