How do you measure the insulation resistance of a transformer?

The insulation resistance of a transformer can be measured using a multimeter, insulation resistance tester and voltage resistance tester. Through measurement, it can be determined whether the insulation resistance of the transformer meets the requirements, so that the corresponding measures can be taken in time.

How do you measure the insulation resistance of a transformer?

1. Use an insulation resistance tester to measure the insulation resistance

· Before insulation resistance measurement, it is necessary to confirm that the transformer has been cut off and connect the power supply of the insulation resistance meter to the circuit. Check the status of the insulation resistance meter and ensure that it works properly ‌.

· Connect the measuring wire of the insulation resistance meter to the high voltage winding and low voltage winding of the transformer respectively.

· Set the measuring parameters of the insulation resistance meter according to the actual situation, including the measuring voltage and measuring range. Select the appropriate measuring range and voltage, which is usually based on the rated voltage of the transformer and the expected insulation resistance value ‌.

· Press the measurement button on the insulation resistance meter to start the measurement. Observe the measurement value on the instrument to ensure the accuracy of the measurement. Usually it is measured for 1 minute or more‌.

· After the measurement is completed, record the measurement value and measurement time for subsequent comparison and analysis‌.

· Analyze the insulation of the transformer according to the measurement results. If the insulation resistance value is large, it indicates that the insulation performance is good; If the value is small, the insulation fault may exist, and you need to rectify it ‌.

· According to the measurement results, corresponding maintenance measures shall be taken to ensure the insulation performance of the transformer‌.

2. Use a multimeter to measure the insulation resistance

· Power off all terminals of the transformer to ensure that the power supply is disconnected.

· Switch the multimeter to insulation resistance and connect the red and black marker.

· Connect the red and black watch pen evenly to the two terminals of the transformer winding and hold it for a period of time until the multimeter is stabilized.

· Read the value on the multimeter and determine whether the transformer is normal. If the multimeter reading is stable at a larger value, it indicates that the insulation resistance of the transformer is good, and otherwise it is necessary to check the transformer.

3. Use a voltage tester to measure the insulation resistance

· Connect the voltage tester to the two terminals of the transformer and turn on the power supply of the tester.

· Adjust the withstand voltage on the tester to the specified value, and increase the voltage to the specified time.

· Read the value of the tester to determine whether the transformer is normal.

· If the tester reading is stable at a large value, it indicates that the insulation resistance of the transformer is good, otherwise it is necessary to check the transformer.

‌Precautions ‌

· Before insulation resistance measurement, it is necessary to ensure that the transformer has been outage and short-circuit discharge to ensure safety and measurement accuracy‌.

· When connecting the measurement line, pay attention to the correct connection of the line to prevent the reverse connection‌.

· Do not touch the live conductor or disconnect the dial wire with your hand during measurement. Discharge the transformer winding ‌ after measurement.

· Record the oil temperature and ambient temperature at that time, in order to convert the measured values to the same temperature for comparison ‌.