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Abstract
Polymeric materials are increasingly being used in the manufacture of high voltage indoor and outdoor insulators in
both distribution and transmission power systems.
The thesis illustrates one of the electrical phenomena on the polymer surface high voltage insulators, called ”dry band arcing”. This phenomenon appears on the surface of rubber blend insulators.
This study beyond to select the suitable characteristics of rubber blend insulators which resist the dry band arcing before electrical failure occurs.
Firstly, the insulator specimens are tested dry to avoid the electrical spark. Then the surface was wetted and the insulators tested again.
The wet surface helps to create a leakage current. The resistance of surface insulator decreases. As a result of leakage current, the wet surface dries and leads to increasing the resistance again. Then an arc can be occurred on air of surface
insulator. The surface of insulator was carbonized. Gradually the surface specimen started to dry allowing the arc moves to the other end of specimen. This arc called dry band arcing.
During this study, many parameters of dry band arcing have been measured such as; arc resistance, resistivity and arc
power of the surface insulator.
The aim of this work is to study completely dry band arcing phenomena on the surface of insulator specimens.
Samples are prepared from ethylene propylene diene monomer rubber ”EPDM” and silicone rubber “SiR” with different
percentage. Five Types have been prepared, 100%of EPDM, 100%of SiR, 40%SiR with 60%EPDM, 50% SiR with 50%
EPDM and 60% SiR with 40% EPDM. Five samples from the same type with the same concentration are used in each test to check the trueness of the results.
The dry band arcing characteristics such as arc resistance, arc resistivity and arc power are calculated from measured data for dry band arcing voltage and dry band arcing current to
select the suitable blend sample of insulating process. Several
tests are studied as; dielectric strength, tensile strength and
surface roughness.
The effect of arc length has been studied to evaluate the arc resistance. Also, another set of rubber blend specimens has been exposures to ultra violet rays (U.V.) with two doses (300hr&500hr), and the results have been reported.) Finally the main salient points of this work have been
summarized and presented, indicating the important of this study as polymers are presently being used worldwide in highly competitive and advance power industry. It may be recommended to use the blend percentage with 60% SiR and
40% EPDM in the industrial application.