Flashover-refers to the discharge phenomenon of high-voltage electrical appliances (such as high-voltage insulators) on the insulating surface, which becomes the surface flashover, referred to as flashover.

Insulation flashover: The discharge phenomenon that occurs on the surface of the insulating material or in the air (ionized gas) in contact with the electrode when the insulation material has not broken down the insulating structure under the action of an electric field, and becomes an insulation flashover.

1. Under the voltage waveform DC, power frequency sine and impulse voltage, the breakdown mechanism is different, and the measured breakdown field strength is also different. The breakdown field strength under the power frequency AC voltage is much lower than that under the DC and impulse voltage.

2.. The voltage application time requires time for both electrical breakdown and thermal breakdown. As the pressure time increases, the breakdown voltage decreases significantly.

3. The uniformity of the electric field and the polarity of the voltage, and the uneven electric field often measures the voltage lower than the intrinsic breakdown value.

4. The thickness and non-uniformity of the sample The thickness of the sample increases, the edge electric field of the electrode becomes more uneven, the heat inside the sample is less likely to be dissipated, and the probability of containing defects inside the sample increases, which will cause the breakdown field Strong drop.

5. Environmental conditions The environmental conditions around the sample, such as temperature, humidity and pressure, will affect the breakdown field strength of the sample; an increase in temperature will usually reduce the breakdown field strength; an increase in humidity will cause the breakdown field Strong drop; the influence of air pressure on the breakdown field strength is mainly for gas. High air pressure increases the breakdown field strength: But when it is close to vacuum, it will also increase the breakdown field strength. There are also: time, radiation, mechanical force, electrode material and polarity effects. 

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