The measurement of the DC resistance of the transformer can effectively discover the material, welding, loose connection of the transformer coil, lack of stock, and other manufacturing defects and hidden dangers in operation.

Testing instruments for measuring the DC resistance of transformers include: double-arm bridge, single-arm bridge, digital bridge, transformer DC resistance tester, DC resistance fast tester, inductive load DC resistance tester, etc.

Analyze the meaning and characteristics of performance requirements and technical indicators:

one. The output current of the tester: The output current of the transformer DC resistance tester is usually between 10mA-50A. In the actual measurement, different test currents should be selected according to different test objects. When the test current is selected to be too large, it will cause the test Product heating affects the accuracy of the measurement results, and will damage the tested product in severe cases. When the selected current is too small, it will affect the measurement accuracy.

two. The output voltage of the tester: The output voltage of the transformer DC resistance tester is 5V/8V/15/V18V/25V/50V, etc. Usually, customers do not consider this parameter when choosing a transformer DC resistance tester. In fact, the output voltage of the transformer determines the speed of measuring the DC resistance of the transformer. The output voltage of the instrument with the same output current is the output of the instrument with high output voltage. The power is large and the measurement speed is fast. Generally, the measurement speed will be four times higher when the output voltage is doubled. When measuring a large transformer, because the test product will produce a large energy consumption during the measurement, the output voltage of the low output voltage will be much slower than the high output voltage during the actual measurement. At present, many low-end products on the market have output voltages below 10V, and some manufacturers produce products whose output voltages are even less than 5V in order to reduce product costs. Therefore, when choosing an instrument, you should not just look at the output current, but also understand the output voltage of the instrument.

three. The measuring range of the tester: The DC resistance of most power transformers is between 100uΩ-100Ω. When it is necessary to measure transformers and other equipment, the measuring range of 100uΩ-2kΩ can meet the requirements.

Four. Basic range: The same measurement accuracy cannot be guaranteed within the measurement range of any kind of instrument. The basic range of the instrument is to test the measurement range of an instrument to ensure the measurement accuracy. The user should select the instrument according to the actual use requirements.

five. Measurement function: The function selection of the transformer DC resistance tester is also very important. It will be very convenient to choose an instrument with a reasonable function design in actual use. Most of the power transformers currently in use are on-load regulating transformers. It is especially recommended to use instruments with conventional measurement functions and on-load functions. Another measurement function is the conversion function of the 20℃ DC resistance value. This function is: input the ambient temperature during the measurement in the instrument before measurement, and the actual measured resistance value and the converted 20℃ can be obtained in the measurement result at the same time. Resistance value at time.