In order to reduce accidents and prevent accidents, the cables in operation should be regularly subjected to preventive withstand voltage tests. The DC withstand voltage test standard of the cable can refer to the relevant cable operation regulations. In principle, the DC withstand voltage test cycle is carried out once a year. The newly laid cable should be tested once every three months after it is put into operation.

1. Type test items of ring main unit body: mandatory type test: protection level inspection: pressure withstand test of inflatable compartment, partial discharge test, type test items of supporting components.

1. Sealing test, gas moisture content measurement (≤150ppm), partial discharge test, electromagnetic compatibility test, X-ray measurement test of vacuum circuit breaker, environmental test, load switch: mandatory type test Insulation test:

Insulation withstand voltage test device, insulation resistance tester, main circuit resistance measurement, temperature rise test (1.1 times rated current), mechanical test, rated short-time withstand current and peak withstand current test 6. Opening and closing Capability test, capacitive current switching test

Mandatory type test:

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