What is the principle of live-line washing for substations?

Why Do Electrical Equipment Need a "Bath"?

Due to atmospheric pollution, contaminants accumulate on insulating porcelain insulators and posts. During rain, this can lead to pollution flashover, which in severe cases may cause insulation breakdown, resulting in short circuits or grounding faults. Therefore, the insulating parts of substation equipment must be periodically washed with water to prevent flashover and avoid insulation degradation that could lead to equipment failure.

Which Equipment Is the Focus of Live-Line Washing?

The main targets for live-line washing include line insulators, disconnect switch support insulators, and transformer bushings. Conductive metal parts—such as conductors, transformer bodies, and switch contacts—must not be washed. Additionally, care must be taken to prevent water from entering terminal boxes to avoid moisture ingress into secondary wiring.

How Is Live-Line Washing Water Different from Ordinary Water?

Yes, there is a significant difference. Common water, including tap or drinking water, contains impurities and various mineral ions that make it conductive. However, the water used for live-line washing undergoes industrial filtration and must have a resistivity of no less than 100,000 ohm·cm. It must also meet the requirements specified in safety regulations sections 11.6.5 to 11.6.8—standards governing the safe procedures for live-line washing.