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Application range of DC high voltage generator

time:2021/3/17   source:华天电力  reading:380 time

DC high voltage generators are widely used in the power industry. Among them, the three major power tests of insulation resistance test, insulation product DC withstand voltage test, and cable test are commonly used.


(1), insulation resistance test

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


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


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(2), DC withstand voltage and leakage test


For good insulation, the leakage current is very small under the action of DC voltage, and at the same time, under the same DC voltage, the current through the insulation decreases with the extension of the pressure time. Good insulation, with the increase of the applied DC voltage, the leakage current increases due to the acceleration of the ion movement speed, but in the not high voltage range, the leakage current is linear with the increase of the applied voltage, and the rise is small.


(3) DC withstand voltage test of rubber and plastic cables

The tested voltage is 3 times the rated voltage of the cable. Under the specified test voltage (the test voltage returns to a high level at 0.5 times the rated voltage for each level, and each segment stays for 1 minute, and the leakage current is recorded; Note: If the leakage current increases disproportionately with the voltage, it must be analyzed in time, Check. Before the withstand voltage, use the high-voltage megohmmeter to check the withstand voltage of the DC high-voltage generator. Use the conventional method to connect, one phase and one phase withstand voltage, one phase to the withstand voltage device and the other two phases to be grounded. , Three-phase resistance three times.

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