The principle of leakage current measurement is basically the same as the insulation resistance, and the measurement of insulation resistance is actually a type of leakage current, which is simply expressed in terms of resistance. However, the normal measurement of the leakage current is applied to the AC voltage, and therefore, the component of the leakage current contains the capacitive component current.
Leakage current is actually the current flowing through the insulation part of an electrical circuit or device without faults and the application of a voltage. Therefore, it is one of the important indicators to measure the quality of electrical insulation. Dare to be the main indicator of product safety performance. The leakage current is limited to a very small value, which has an important role in improving product safety performance.
The leakage current tester is mainly composed of impedance conversion, range conversion, AC-DC conversion, amplification, and indication devices. Some also have over-current protection, sound and light alarm circuit and test voltage adjustment device, and its indicating device is divided into two kinds of analog and digital.
Operation method 1, plug in the power, connect the power switch, power indicator light;
2, select the power range, press the desired current button;
3, select the leakage current alarm value;
4, select the test time;
5. Connect the DUT to the measurement terminal, start the instrument, and increase the test voltage to 1.06 times (or 1.1 times) the rated working voltage of the DUT. Switch the phase changeover switch to read the second reading and select a large value. Reading leakage current value. When the transfer switch K is connected to the neutral line, the tester samples the leakage current between the neutral line and the case. When K and the phase line are connected, the leakage current between the phase line and the case is tested. It must be noted that: K is connected to the zero line or K is connected to the phase line, and the leakage current is not necessarily the same. This is because the location of the weak points in the insulation of household appliances is random. Therefore, the leakage current test should be converted by K polarity, whichever is greater as the leakage current value of the electric appliance under test.
Test Note 1. When the leakage current is measured at the operating temperature, if the device under test is not powered by an isolation transformer, the device under test shall be insulated from the ground by a material insulating mat with reliable color insulation performance. Otherwise, some of the leakage current will flow directly through the ground without passing through the instrument, affecting the accuracy of the test data.
2. Leakage current measurement is carried out with electricity, and the shell of the device under test is charged. Therefore, the test personnel must pay attention to safety, all kinds of laboratories should formulate safe operating procedures, and must not touch the device under test before cutting off the current.
3. The influence of the environment on the test data should be minimized. The temperature, humidity, and the pollution of the insulation surface should be tested. The leakage current has a great influence. The temperature is high, the humidity is high, the insulation surface is heavily polluted, and the measured leakage current value is higher. Big.
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