Study on the required creepage distance for HVDC equipment at indoor conditions

Summary

In many applications, especially under DC voltage, to build a closed shelter (a hall) with high voltage apparatus installed inside may be advantageous. However, same as for the outdoor cases, wetted pollution is still one of the hazards for insulation design. The severity of this hazard will be determined by the amount of pollution as well as the intensity and duration of the wetting process, which in turn will be determined by the building standard. In order to facilitate the discussion on the design criteria for indoor conditions, test results from artificial pollution tests have been presented in this paper. These tests were designed to simulate the indoor conditions, i.e., without direct precipitation. The pollution was wetted by highly humid air with the relative humidity level up to 95%. For pollution level, the worst-case scenario was investigated with SDD in the range of 0.28 to 3.36 mg/cm2 and NSDD of 5 mg/cm2. The test results showed that with wetting by humid air without direct precipitation, the test severity is significantly lower than that with clean fog test which is intended to simulate outdoor conditions. For the indoor conditions much shorter creepage distance could be adopted even under the conditions that much pollution may penetrate into the shelter.

Additional informations

Authors

DONOSO, SOTTERO

Keywords

External Insulation, Indoor, HVDC, Pollution test, Creepage distance