All About the Role of Winding Resistance Testing in Power Transformations

Transformers are an important component of any substation. Apart from being very costly, these are very reliable too and can serve you for a long period if maintained properly. Accurate and reliable testing methods are important to ensure smooth running and protection against failures which results in costly repairs and frustrating downtimes.

What is winding resistance?

It is the resistance of a length of copper wire or bars from one end to the another and is a measure of DC voltage and current.

When to carry out winding resistance measurements?

It is generally carried out with new transformers to detect any transit damage before putting into service and after they have been delivered to the site. It makes the basis for comparison of measurements taken later in the lifespan of the device.

Carried out as a type or routine or even as a field test, it helps in detecting the following in a factory setup:

1. Calculation of I2R losses in a transformer.
2. To calculate the winding temperature after the temperature rise test in transformer ends
3. To assess various probable damages in the field by setting a benchmark for it first.

These tests, of finding the winding resistance are invaluable when you are finding faulty transformers
Some of the faults which can be easily detected through winding resistance test are as follows:

1. Open and shortened turns
2. Defects in internal connects
3. Issues faces with tap changer contact, which also includes open circuits during the in load tap changer operations.

What other tests does it compliment?

Data gathered from winding resistance tests is useful for other diagnostic tests like FRA which is also known as the Frequency response analysis, Dielectric Frequency response (DFA) and power factor measurements. The measurements help to determine the winding losses.

So this sums up the role of winding resistance testing in power transformers.

It is crucial to have an accurate and effective winding resistance tester in your arsenal to carry out these important measurements. The fully automatic TRT-27 series from UdeyRaj is a new generation digital resistance meter using 4 terminal measurement technique. Encased in an aluminum alloy cabinet and equipped with a digital display and printer, it is able to carry out tests a lot quicker.

UdeyRaj Electricals Pvt Ltd, was established in 1958 as Udeyraj and Sons, and since then it has become a pioneer in research, design and manufacture of Utility Power Test and Measurement Equipment, thus also earning the badge of one of the most trusted high voltage tester manufacturer in India.
We offer customer satisfaction and assurance of safety and world class quality with all our products. Our work speaks for ourselves and so does our clients ranging from Indian Railways to Reliance to Tata power to Essar and other bigshots of the industry.

Feel free to contact us at and we guarantee you a world class experience.

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