When the test voltage is added to the specified voltage value, keep it for the specified time. If the test product has no destructive discharge and the pointer of the microammeter does not suddenly swing in the increasing direction, the DC withstand voltage test can be considered qualified. The value of the leakage current is not only related to the nature and state of the insulation, but also related to the structure of the insulation, the capacity of the equipment, the ambient temperature, and the degree of contamination of the equipment. Therefore, it is not possible to roughly judge whether the insulation is only based on the magnitude of the leakage current. Good, it is important to observe its temperature, time, voltage and other characteristics and compare it with the test results based on previous experience, and compare it with the same type of equipment. Compare the same equipment to make comprehensive judgments. Attention should be paid to the following situations:

1. If the pointer of the microammeter swings back and forth during the test and the swing amplitude is relatively small, AC components may flow through. The protection circuit and filter capacitor of the microammeter should be checked. If the pointer swings periodically and the amplitude is relatively large, then It is possible that the insulation of the test product is poor and periodic discharge occurs, and the cause should be investigated.

2. If the leakage current is too large or too small, it is an abnormal phenomenon. If the current is too large, check the condition of the loop equipment and whether the shielding is good to eliminate the influence of objective factors. If the current is too small, check whether the wiring is correct and whether the microammeter circuit is correct. normal.

3. If the reading rises gradually over time, the insulation may be aging.

4. If the pointer swings in the decreasing direction during the test, the unstable power supply may cause fluctuations. If the pointer suddenly swings in the increasing direction, it may be a flashover of the tested product or the test circuit.