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High voltage test transformer test method

time:2020/11/7   source:华天电力  reading:219 time

High-voltage test high-voltage device refers to a type of transformer that generates high voltage for high-voltage test. The high-voltage test transformer has the characteristics of high voltage, small capacity, short continuous working time, thick insulation and usually one end of the high-voltage winding is grounded


experiment method:


Non-destructive test and destructive test


Non-destructive test: the test is carried out at a lower voltage (below or close to the rated voltage). Test items such as measuring insulation resistance, leakage current and dielectric loss angle are non-destructive tests.


Destructive test: refers to a test performed at a voltage higher than the working voltage, also called a withstand voltage test. During the test, a specified test voltage is applied to the insulation of electrical equipment to test the withstand capability under this voltage. Both DC withstand voltage test and AC withstand voltage test are destructive tests.


Hipot Test Set.png


There is a certain sequence of these two types of tests. The non-destructive test should be carried out first, and then the destructive test should be carried out, so that undue breakdown accidents can be avoided.


1. AC withstand voltage test


It is one of the destructive tests, which can further diagnose the insulation defects of electrical equipment. The AC withstand voltage test is a strict, effective and most direct test method to identify the insulation strength of electrical equipment. It can detect the weakest point of the insulation during normal operation and is decisive for judging whether the electrical equipment can continue to be put into operation.


2. DC withstand voltage test


In addition to detecting moisture and deterioration of the equipment insulation, it has a special effect on finding some local defects of the insulation. The DC withstand voltage test can find some defects that cannot be found in the AC withstand voltage test. The two tests of AC and DC withstand voltage test cannot replace each other. They must be used in preventive tests at the same time, especially for motors and cables. DC withstand voltage test.


3. Measure insulation resistance


It is a commonly used and simple test method, usually measured with a megohmmeter. According to the measured insulation resistance of the sample at 1 minute, it can be detected whether the insulation has penetrating concentrated defects, overall moisture or penetrating moisture.


4. Measure leakage current


It is basically the same as the principle of measuring insulation resistance, and the nature of the detected defects is also roughly the same. However, the power used in leakage current measurement is generally provided by high-voltage rectifier equipment, and the leakage current is directly read with a microammeter. It has the test voltage that can be adjusted at will; high sensitivity, good measurement repeatability; conversion of insulation resistance value; can be used to measure the absorption ratio to judge insulation defects and other characteristics.


5. Measurement of dielectric loss angle of high voltage test transformer


It is a highly sensitive test item. It can find local defects such as damp, deterioration, deterioration of the insulation of electrical equipment as well as the penetration or failure of the small-volume test equipment. But when the volume of the test product is large, and the volume of the defect is small, it is difficult to find with this method. It is widely used in electrical manufacturing and electrical equipment handover and preventive tests.


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