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What is Insulation (Insulation) Resistance-Insulation (Insulation) Resistance Test?

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What is Insulation (Insulation) Resistance?

Insulation (insulation resistance) is used to measure the resistance value of the insulation (insulation) power of large transformers, transformers, generators, high-voltage motors, power capacitors, equipment such as power cables and arresters.

What is Insulation (Insulation) Resistance Test?

The insulation (insulation) resistance test measures the total resistance between any two points separated by electrical insulation. The purpose of measuring the insulation resistance of a transformer is to test the integrity of the winding Insulation, better Insulation means lower leakage current and better operating performance and safety. Because the insulation resistance is very high, an Insulation resistance tester with a higher voltage level is usually chosen to measure the insulation resistance. Test measurement values ​​are affected by variables such as temperature, humidity, test voltage and transformer size. This test should be performed before and after repair or maintenance. Test data should be recorded for future comparison purposes. For comparison purposes, the test values ​​should be normalized to 20°C.

For example; 1 MΩ plus 1 MΩ for every 1000 V of applied test voltage. Sample resistance values of Good Insulation systems are shown in the Table below.

What is the Purpose of Insulation (Insulation) Resistance Test?

The leakage current levels depend on the integrity of the winding insulation (insulation). For example, insulation (insulation) can deteriorate over time due to extreme temperature or humidity, or exposure to a voltage higher than the ratings. In this case, the voltage level that the insulation (insulation) could withstand before may have dropped, which will increase the leakage current. The performance of a transformer depends, among other things, on its construction, and if the insulation (insulation) is not the same, it will underperform or be dangerous in some cases.

Therefore, the primary purpose of insulation (insulation) resistance in a transformer is to test the integrity of the winding insulation (insulation). Better isolation means lower leakage currents and better performance and safety.


Insulation Resistance Tester 5 KV | MT-215

Insulation Tester
| MT-205

Programmable Insulation Tester | MT-5120


Our Test Equipment with Suggestions for Insulation Testing;