Wuhan UHV specializes in producing series resonance (also known as cable withstand voltage test device). Next, we will share with you the specifications for cable withstand voltage test.
Power cables are composed of wire cores, insulation layers, shielding layers, and protective layers. They are mainly used for power generation, distribution, transmission, transformation, power line transmission, and continuity. They are an important part of achieving safe operation of the power system. So, which items are measured for power cables in preventive testing projects?
Cable voltage withstand method
According to the standard for electrical equipment handover testing, it is no longer recommended to use DC voltage for voltage withstand testing of cables. After research, it has been found that the uneven distribution of electrical resistivity of cables under DC is more likely to cause flashover faults and power outages during operation. Theory and practice have proven that the series resonance testing device is the most rigorous test for power cables. Therefore, it is recommended to perform series resonance voltage withstand and ultra-low frequency voltage withstand on cables, which is commonly known as "series resonance".
In addition, the power cable testing project also includes the following items:
(1) Measure insulation resistance;
(2) Measure the ratio of shielding layer resistance to conductor resistance;
(3) Check the phase at both ends of the cable;
(4) Insulation oil test for oil filled cables;
When conducting power cable tests, the following specifications should be met:
Before using a series resonance test device or a 0.1Hz ultra-low frequency generator to withstand voltage on the cable, the insulation resistance of each phase should be measured separately. Only after passing the measurement and recording can AC withstand voltage be carried out. When measuring one phase, the other two phases of conductors, metal shielding, or metal armor layers should be reliably grounded together. The cable line should be measured using a 2.5kV or 5kV insulation resistance meter, and the insulation resistance should not be less than 0.5M Ω/km. After the experiment, there should be no significant change in the insulation resistance detected.