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Correct Usage of Transformer DC Resistance Tester - Yangzhou Darui

The DC resistance tester provides two types of power supply for testing: AC220V/DC12V. In the case of strong electromagnetic field interference, it is recommended to use DC power for testing, as the test values are stable and have strong anti-power frequency interference capability under this state.

DC power testing:

Close the main power switch (DC12V), and the corresponding indicator light will illuminate. Close the main power switch, and the corresponding indicator light will illuminate. Press the "Start/Stop" key to begin testing. After testing, turn off the main power switch (DC12V), and the corresponding indicator light will go out. After discharging, switch the test clips and proceed with the next test.

AC power testing:

Connect the AC220V power supply, and the corresponding indicator light will illuminate. Close the main power switch, and the corresponding indicator light will illuminate. Press the "Start/Stop" key to begin testing. After testing, turn off the main power switch (AC220V), and the corresponding indicator light will go out. After discharging, switch the test clips and proceed with the next test.

Charging:

Connect the AC220V power supply, and the charging indicator light will illuminate, indicating that the transformer test is charging the internal rechargeable battery. When the instrument is using AC power for testing, it is also charging the internal battery simultaneously. (The instrument is designed with a charging protection circuit to prevent overcharging.)

Connection method for test leads:

Connect the I+, V+, V-, and I- terminals of the instrument to the test object as shown in Figure 1.

This connection method eliminates the contact resistance at points A, B, C, and D, as well as the influence of lead resistance on the measurement. The measured value is the resistance Rx between B and C (Note: do not reverse the connections between B and C).

In use, if the test leads provided with the instrument are not long enough, you can extend them with wires of equivalent diameter.

Measurement:

Transformer DC Resistance Tester When the circuit is not properly connected, the meter displays "E0000" upon power-on. After connecting the measurement leads as shown in Figure 1, select the appropriate resistance range based on the value to be measured, and press the corresponding range switch. The indicator light for that range will illuminate, and the stable value displayed on the four-and-a-half-digit LCD is the measured resistance. Please pay attention to the unit of the selected range when reading the value. When measuring large inductive test objects such as power transformers, short-circuit other coils not being measured in the test circuit to avoid electromagnetic interference.

Discharge:

After testing, you can directly turn off the main power supply. If the test object is inductive, do not disconnect the leads immediately after turning off the power; allow the instrument to have a continuous discharge process. Generally, discharge for at least 20 seconds, otherwise the back electromotive force of the inductor may endanger personal safety.