The DC resistance tester can reflect the short circuit between winding turns, the broken strand of the winding, the contact state of the tap switch, the difference of the wire resistance and the poor contact of the joints and other defects. It also judges whether the DC resistance of each phase winding is balanced and the voltage regulator switch is correct. Effective means. The measurement of the DC resistance of the transformer winding can find some major defects in the loop, and the sensitivity and accuracy of the judgment are also high. However, the following 5 requirements should be followed in the field test to obtain an accurate diagnosis.

1) When measuring and analyzing the DC resistance of the transformer, the inductance is relatively large, and it must be charged in place to reduce the self-inductance effect to a small extent. After the indicator pointer is basically stable, read the resistance value to improve the accuracy of the primary loop DC resistance measurement. Sex and accuracy.

2) The measured data should be compared horizontally and vertically, and the temperature, humidity, measuring instrument, measuring method, measuring process and measuring equipment should be analyzed.

3) When analyzing data, relevant factors and criteria must be considered comprehensively. The standard values of the regulations cannot be used alone, but the development and change process of the equipment measurement data must be analyzed in accordance with the ideas of the regulations and the specific conditions of the site.

4) According to the specific structure of the equipment, analyze the specific conditions inside the equipment, and measure the DC resistance according to different conditions to get the correct judgment conclusion.

5) Pay attention to the analysis, judgment and verification of comprehensive methods. For example, in some schemes, the voltage ratio test of the winding taps can effectively verify the tap-related gears and verify whether the connection group of the transformer windings is correct.