The connection and principle of the DC leakage current pass test and the DC withstand voltage test are the same, and they are developed simultaneously. The leakage current can be measured and the principle analysis of the insulation resistance measurement is the same. The main difference is to increase the power supply used when measuring the data leakage current Management General enterprises use adjustable DC high-voltage devices, and use a microammeter to directly affect the current flowing through the test sample. The leakage current measurement has the following advantages compared with the insulation resistance measurement method:

(1) The test voltage is high and can be adjusted at will. The corresponding DC test voltage is applied according to the different voltage levels of the test sample, which is much higher than the megohmmeter. For example, a 40kV DC high voltage is applied to the primary winding of a 110kV transformer. Therefore, it is easier to find certain insulation defects (such as porcelain insulation cracks, local damage, insulation oil deterioration, insulation surface carbonization, etc.) than measuring the insulation resistance with a megger. .

(2) Use a microammeter to monitor the leakage current of the system, which has high sensitivity and can be used repeatedly for comparison.

(3) The insulation resistance value can be converted between the measured values of the current generated by the data leakage, while the insulation resistance value measured by the megohmmeter generally cannot be converted into the leakage current value. This is because the enterprise is based on the load of the megohmmeter. Work characteristics. The output terminal voltage of the megohmmeter is related to the insulation resistance value of the tested product and is not necessarily the standard working voltage of the megohmmeter nameplate data.

(4) Leakage current test can produce the relationship curve of leakage current and pressure time, leakage current and width. The insulation status can be judged by these curves.