Sage-Tips

What is flashover of insulator?

A flashover is an electric discharge over or around the surface of an insulator. When an electrical flashover occurs, conductors can vaporize, expanding to thousands of times their original volume. A flashover is an electric discharge over or around the surface of an insulator.

What is difference between puncture voltage and flash over voltage of an insulator?

As puncture destroys the insulator, it is more serious than flash-over. Insulators are designed with a puncture voltage of about twelve times and a flash-over voltage of about six times the working voltage.

What is electrical puncture?

A rock fracturing technique, applied to secondary fragmentation in quarries, that is characterized by an almost instantaneous action and is accompanied by a mechanical weakening of the dielectric and a lowering of the resistance of the puncture path.

What is a flashover fire?

Flashover is a thermally-driven event during which every combustible surface exposed to thermal radiation in a compartment or enclosed space rapidly and simultaneously ignites. Flashover normally occurs when the upper portion of the compartment reaches a temperature of approximately 1,100 °F for ordinary combustibles.

Why do insulators puncture?

Simply, it means electrical discharge occurs from conductor to pin through the body of the insulator. Generally, the pin insulator is designed with a factor of safety. Basically, insulator puncture will occur due to switching over voltage and lightning.

What is flashover voltage?

Definition of flashover voltage : the voltage at which a current flashes from electrode to electrode or ground with the formation of a sustained arc.

What is insulator puncture?

A puncture is a breakdown and conduction of the material of the insulator, causing an electric arc through the interior of the insulator. Simply, it means electrical discharge occurs from conductor to pin through the body of the insulator. Generally, the pin insulator is designed with a factor of safety.

What is flashover distance?

Flashover distance – It is the shortest distance through air between the electrodes of the insulator.

What is flashover voltage of insulator?

The flashover voltage is the lowest when the insulator is polluted with metal pieces because metal is a good conductor. Hence, current can flow through the insulator surface easily. The flashover voltage is lower when the insulator is polluted with wet sand compared to dry sand.

Which takes place first – insulator puncture or flash over?

It is expected that Flash over to take place first as Insulator Puncture damages the Insulator and after puncture of insulator it needs to be replaced. Insulators are designed with a puncture voltage of about twelve times and a flash-over voltage of about six times the working voltage.

What is the difference between puncture and flash-over?

As puncture destroys the insulator, it is more serious than flash-over. Therefore Safety Factor is defined for an Insulator. Safety factor of an Insulator is defined as the ration of Puncture Voltage to the Flash Over Voltage.

What is the puncture voltage of insulator?

Insulators are designed with a puncture voltage of about twelve times and a flash-over voltage of about six times the working voltage. Failures occurring in practice are usually due to lightning or to deposits of soot or sea salt on the insulator surface.

What happens to the insulator during a flashover?

The insulator is not damaged by the flashover, but it’s become useless after the puncture. The sufficient thickness of the material is provided in the insulator to prevent the puncture under surge condition. The flashover is reduced by increasing the resistance to leakage currents.