1. DC withstand voltage and leakage test
For good insulation, the leakage current is very small under the action of DC voltage. With the increase of DC voltage, the passing current decreases. Under the condition of good insulation, with the increase of applied DC voltage, the leakage current will increase due to the rapid movement of ions. However, in the low voltage range, the leakage current has a linear relationship with the increase of the applied voltage, and the increase range is very small.
2. Zinc oxide arrester test
DC high-voltage generator is specially equipped with zinc oxide arrester test function. It can increase the voltage to 1mA leakage current, and then press the button 0.75 times. The instrument can automatically reduce the voltage to 0.75 times. At this time, the leakage current is 0.75 times of the measured zinc oxide leakage current U1mA. This current can reflect the insulation state of zinc oxide arrester.
3. Insulation resistance test
Insulation resistance is the most basic insulation index of electrical equipment and circuits. When DC voltage is applied to the dielectric, after a period of time, the resistance corresponding to the leakage current flowing through the dielectric is called insulation resistance.
When the DC high-voltage generator is used to pressurize the measured material, the current on the measured material will not immediately reach a stable value, but there will be a decay process. At the same time of pressurization, a relatively large charging current flows through, followed by a relatively long slowly decreasing absorption current, and finally a relatively stable conductive current is obtained. The higher the measured resistance, the longer it takes to reach the balance. Therefore, in order to correctly read the measured resistance value during the measurement process, it should be read after the value is stable.
4. DC withstand voltage test of rubber and plastic cable
The voltage after the test is 3 times the rated voltage of the cable. Under the specified test voltage (the test voltage shall be increased by 0.5 times of the rated voltage of each level in sections, and the leakage current shall be recorded for 1 minute in each section; note: if the leakage current and voltage increase disproportionately, it must be analyzed and checked in time. Before withstand voltage, check the withstand voltage of DC high voltage generator with a high-voltage megger e method is the traditional wiring method. One phase withstand voltage, one phase with a withstand voltage device, the other phase is grounded, and the three-phase resistance is three times.
