Cap And Pin Insulator Failures

Fingerprint dive into the research topics of investigation of electrical failures in porcelain cap and pin line insulators.

Cap and pin insulator failures.

Each failure mode has specific consequences on service performance of an insulator and the string that contains any failed units. In typical failures that occur naturally the primary failure is degradation of the cement. Often no permanent damage is done by lightning flash over. In some cases failure will result in complete loss of service as in separation of the cap from the pin or breakage of the fiberglass core rod in both cases with dropped conductors.

Since that time similar failures have occurred on 12 47 kv 34 5 kv 41 8 kv and 69 kv bus installations at many other locations. Every porcelain insulator has a porcelain shell and cement between the cap and the pin. Failure modes of insulators. Lightning affects the design of the transmission line rather than that of the insulators.

Download citation investigation of electrical failures in porcelain cap and pin line insulators suspension and dead end porcelain insulator strings were removed after 25 30 years in service. Suspension and dead end porcelain insulator strings were removed after 25 30 years in service for various reasons and the insulator bells units were evaluated in the laboratory. As previously mentioned prcelain pin type and cap and pin insulators may suffer punctures between the pin and the either the pin or the high voltage conductor. For supporting the conductors of overhead power lines many utilities use strings of porcelain cap and pin insulators.

Failures of pedestal type pin and cap insulators the problem of failure of pedestal type insulators first appeared on a 34 5 kv bus at a reclamation substation in 1962. Enlarge the information available on reliability of cap pin insulators possibly leading to results surprisingly different from the past see my q1 2011 column in inmr. Failures occurring in practice are usually due to lightning or to deposits of soot or sea salt on the insulator surface. Taking into account the evolution of the insulator industry in recent years and the growing body of available service experience i make the following recommendations.

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