How to prevent lightning in power transformers

2019-06-21 09:49:07 JUKE CHINA ODM OEM Transformer factory Read

How to prevent lightning in power transformers

The Power Transformers we usually use sometimes cause lightning-induced lightning accidents in thunderstorms, mainly because of the over-voltage caused by the "positive and negative transformation" of the distribution system, and the reverse-transformed over-voltage damage accident. See how the power transformer is lightning protection.
Positive Transform Overvoltage When the low voltage side line is struck by lightning, the lightning strike current intrudes into the low voltage winding and enters the ground through the neutral point grounding device. The ground current generates a voltage drop across the grounding resistance. This pressure drop causes the neutral point potential on the low voltage side to rise sharply. It superimposes an overvoltage in the low voltage winding, jeopardizing the low voltage winding. At the same time, this voltage is raised to the high voltage side by the electromagnetic induction of the high and low voltage windings, superimposed with the phase voltage of the high voltage winding, causing a dangerous overvoltage in the high voltage winding. This phenomenon occurs because the low-voltage winding is subjected to lightning overvoltage and is converted to the high voltage side by electromagnetic induction, causing the overvoltage of the high voltage winding to be called "positive change" overvoltage.

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Reverse conversion overvoltage When the high voltage side line is struck by lightning, the lightning current is discharged into the ground through the high voltage side arrester, and the ground current generates a voltage drop across the grounding resistance. This pressure drop acts on the low-voltage side neutral point, while the low-voltage side outlet line is equivalent to grounding through the resistor at this time. Therefore, most of the voltage is applied to the low-voltage winding. Further, by electromagnetic induction, this voltage drop rises to the high voltage side in a variable ratio and is superimposed on the phase voltage of the power transformer of the high voltage winding, causing an overvoltage in the high voltage winding to cause a breakdown accident. This phenomenon is caused by a lightning strike on the high voltage side, acting on the low voltage side, and changing to the high voltage side by electromagnetic induction, causing the phenomenon of overvoltage of the high voltage winding to be called "inverse conversion overvoltage".
The use of power transformers must not only pay attention to the forward and reverse transformation, but also the lightning protection of the distribution transformer.