Research On Power Frequency Withstand Voltage Test Of XLPE Cable Insulation Checking

With the reformation and opening in China, people's living level is becoming more and more high, and the desire for the green and the space is more and more strong. Power delivery by electric cable can occupy less land and be more concealed, extend the space in the city, and make the city more beautiful. In the other hand, it is safe to human body, easy to operate and maintain. As a result, the electric cable is more preferable and used in necessary area. After the electric cable was constructed, test on high-voltage withstand capacity is always regard as one of the important tests on whether or not the cable can operate safely, especially to high-voltage cable, High DC voltage is the first choice in the past, just for that the equipment is light, small capacity, easy to remove. But some domestic research institutions think that in the DC voltage withstanding test on the XLPE cable, because of the effect of the space charge, actual electric field intensity in the insulation can be 11 times of the work electric field, the insulation of XLPE cable can be destroyed badly even it has passed DC voltage test. Secondly, because the distribution of DC voltage filed intensity is not equivalent to the AC test, and DC test cannot truly simulate the over voltage that the cable withstand in the operation and find the lacuna of cable and the cable tie-in and the product manufacture technique. So that, more importance is attached to the XLPE cable voltage withstand test using not DC. Because the states of the power frequency withstand test are close to the cable's operating conditions, and the voltage of the power frequency withstand test is lower, and it can reflect the cable's insulation and find the flaws in insulation even more as the extension of the withstand times. The article introduces the cable's test criteria in the world, and compares various withstand voltage tests, and indicate the limitation of the DC withstand voltage test. The article analyzes the principle that the power frequency withstand voltage test checks the XLPE cable's insulation flaws, and after a lot of tests, discoveries change rules of shorting voltage to various flaws, and draw a conclusion that it can discover the water branch flaw under the lower power frequency voltage relative rules. And the author uses the measurement of resistant current to check the XLPE cable's insulation flaws. The theories and the experiments prove that the method is really feasible that use the measurement of resistant current to check the XLPE cable's insulation flaws.