A typical four-wire measurement method is used. In order to improve the accuracy of measuring resistance (especially low resistance). Program-controlled constant current source, program-controlled preamplifier, and A/D converter constitute the main body of the measurement circuit. The central control unit applies a constant, high-precision current to the external load under test by controlling the constant current source, and then processes the obtained data (including test voltage, current test current, etc.) to obtain the actual resistance value.

The function selection of the DC resistance tester is also very important. It is very convenient to choose an instrument with 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.

Three conditions for the switch resistance source of the DC resistance tester:

1 High frequency: The task of resistive force resistor components is at high frequency instead of low frequency close to the power frequency

2 Switch: The task of resistive force resistance sub-device is in the on-off state instead of the linear state

3 DC: DC input by switching resistance source instead of exchange