DC high voltage generator(DC Hipot Tester) is mainly suitable for electric power, mining, metallurgy, steel and other enterprises to conduct DC withstand voltage test on high voltage electrical equipment such as zinc oxide arresters, power cables, transformers and generators. Among them, insulation resistance test, insulation product DC withstand voltage test, and cable test are the three most commonly used power tests.
(1) Insulation resistance test
Insulation resistance is the most basic insulation index for electrical equipment and electrical circuits. Applying a DC voltage to the dielectric, after a certain period of time the polarization process is over, the resistance corresponding to the leakage current flowing through the dielectric is called the insulation resistance.
When using a DC high voltage generator to pressurize the material under test, the current on the material under test does not reach a stable value instantaneously, but has a decay process. While pressurizing, a relatively large charging current flows, followed by a relatively long-term and slowly decreasing absorption current, and finally a relatively stable electrical conduction current is achieved. The higher the measured resistance value, the longer it takes to reach equilibrium. Therefore, in order to correctly read the measured resistance value during measurement, the value should be read after it stabilizes.
(2) DC withstand voltage and leakage test
For good insulation, the leakage current is very small under the action of DC voltage. At the same time, under the same DC voltage, the current through the insulation decreases with the extension of the pressure time. With good insulation, with the increase of the applied DC voltage, the leakage current increases due to the faster ion movement speed. However, in the voltage range that is not too high, the leakage current has a linear relationship with the increase of the applied voltage, and the rise is small.
(3) DC withstand voltage test of rubber plastic cable
The voltage is 3 times the rated voltage of the cable after the test. Under the specified test voltage (the test voltage is increased in sections at 0.5 times the rated voltage for each level, and each section stays for 1 min, and the leakage current is recorded; Note: If the leakage current increases disproportionately with the voltage, it must be analyzed in time , Inspection. Before the withstand voltage of Guodian Xigao, use the high-voltage megohmmeter to check the withstand voltage of the DC high-voltage generator. The method of use is the conventional method of connection, one phase with one phase withstand voltage, one phase with a withstand voltage device, and another Two-phase grounding, three-phase resistance to three times.