Cap And Pin Insulator Failures

After a period of time and expansion and contraction.

Cap and pin insulator failures.

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. The corrugation increases the creepage length so consequently increasing resistance to the insulator leakage current. Before going through testing of insulator we will try to understand different causes of insulator failure because insulator testing ensures the quality of electrical insulator and chances for failure of insulation depend upon. These cap and pin replacement insulators are of the correct height bolt circle electrical characteristics and mounting configuration to permit direct substitution for the cap and pin or cap and pin stack.

The corrugation below the insulator is for the purpose of obtaining longer creepage path between the pin and cap. 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. To ensure the desired performance of an electrical insulator that is for avoiding unwanted insulator failure each insulator has to undergo numbers of insulator test. The situation becomes more complicated when an insulator fails electrically but not mechanically.

Between the socket cap and the pin of each porcelain insulator. 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. Causes of insulator failure. Every porcelain insulator has a porcelain shell and cement between the cap and the pin.

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. The electrical failure of insulator occurs either by puncture or flashover. Cap and pin replacement insulators 26 cap and pin selection chart 28 switch operating rod insulators 30 electrostatic rain deflectors transition plates and spacers 31 part number conversion table cavity core to solid core 32 numerical index inside back cover. These failures which are apparently due to cement.

Insulator failures an overview. In typical failures that occur naturally the primary failure is degradation of the cement. The pin of the insulator damaged the insulator thread. In other cases less serious failures might occur such as partial damage to discs or housings or shattering of the glass shell which has no immediate.

The flashover is caused due to the arc discharge between the conductor and the earth through air surrounding the insulator. The leakage current that flows through the surface of.