1. Insulation resistance test

Insulation resistance is the most basic insulation index of electrical equipment and circuits. When a DC voltage is applied to a dielectric, the resistance corresponding to the leakage current flowing through the dielectric after a certain period of time is called insulation resistance.

When a DC high voltage generator is used to pressurize the material under test, the current on the material under test will not reach a stable value immediately, but there will be a decay process. While pressurizing, a relatively large charging current flows, followed by a relatively long and slowly decreasing sink current, and finally a relatively stable conduction current is obtained. The higher the measured resistance, the longer it takes to reach equilibrium. Therefore, in order to correctly read the measured resistance value during the measurement, it should be read after the value is stable.

2. DC withstand voltage and leakage test
For good insulation, the leakage current is very small under the action of DC voltage. As the DC voltage increases, the passing current decreases. In the case of good insulation, as the applied DC voltage increases, the leakage current increases 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 small.

3. DC withstand voltage test of rubber and plastic cables

The voltage after the test is 3 times the rated voltage of the cable. Under the specified test voltage (the test voltage should be increased by 0.5 times the rated voltage of each stage, and the leakage current should be recorded for 1 minute in each section; Note: If the leakage current increases in proportion to the voltage, it must be analyzed and checked in time. Before withstand voltage, use high voltage The megohmmeter checks the withstand voltage of the DC high-voltage generator. The method is the traditional wiring method. One phase withstands voltage, one phase has a withstand voltage device, the other phase is grounded, and the three-phase resistance is three times.

4. Zinc oxide arrester test

The DC high-voltage generator is specially equipped with the zinc oxide arrester test function. It can increase the voltage up to 1mA leakage current with 0.75 button presses. The instrument can automatically reduce the voltage to 0.75 times the voltage. 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 the zinc oxide arrester.