How to choose test current of our GDZC Transformer Winding Resistance Tester?

The transformer DC resistance tester is subdivided into various specifications such as 1A, 3A, 5A, 10A, 20A, 40A, 50A, 100A, etc. The power supply of the instrument is divided into external power supply AC220V, internal power supply (battery power supply), AC and DC power supply, etc. At present, the DC resistance testers above 10A are not battery-powered.

When customers choose a DC resistance tester for transformers, they usually do not know how much current the DC resistance tester should be. In many cases, the selected DC resistance tester is not reasonable.

Performance requirements and technical indicators and characteristics analysis of transformer DC resistance tester:

1. Current and voltage: In actual measurement, different test currents should be selected according to different tested objects. When the selected current is too small, it will affect the measurement accuracy. The output voltage determines the speed of measuring the DC resistance of the transformer

2. Measurement range: The DC resistance of general power transformers is between 100uΩ-100Ω, and the measurement range of high-power inductors and other equipment is between 100uΩ-2kΩ

3. Measurement accuracy: Of course the higher the better

4. Instrument function: single-phase measurement and three-phase measurement, data storage and printing

In principle, the larger the transformer capacity, the larger the test current is required for instrument selection. When the transformer is tested for DC resistance, it is generally measured at 10% of the transformer's rated working current. Too much current will cause the temperature of the transformer to rise, resulting in inaccurate resistance testing, and too small a current will result in poor testing accuracy.