When thinking about transformer testing, TTR ranks number one in the routine maintenance testing for most engineers. It provides a good starting point for transformer diagnostics, in that it tests that the transformer is doing what it is supposed to do.
When it comes to uncovering problems that may not yet be impacting operations, DC winding resistance testing is regarded as the key diagnostic tool for proper on-load (OLTC) and de-energized (DETC) tap changer operation. Of components that fail in transformers, tap changers constitute a major and, by some statistics – leading, percentage component category. DC winding resistance testing also indicates problems such as loose, defective or incorrect connections in the general current-carrying path (such as winding exit leads); problems which cause enough transformer failures each year to be regarded as a failure category of its own.
However, the test tends to be neglected due to a number of concerns and challenges surrounding winding resistance.
But transformer testing has changed dramatically over recent years, so those concerns and challenges have become outdated. Winding resistance isn’t as troublesome as it used to be.
Winding resistance has a stigma attached to it due to a number of factors:
That stigma is hard to shake, but things are different now. While the above concerns are all very valid, new technologies have allowed both these tests to be carried out much quicker, safer and easier.
Megger’s MWA test set performs both turns ratio and winding resistance tests from just one instrument, with just one connection. Designed specifically to make the measurement of ratio and winding resistance safer and more efficient, without compromising on accuracy of the results.
The MWA has the potential to change the way you think about maintenance testing, and ultimately provide much more accurate and comprehensive view of your assets’ health.
For more information, complete the form below to request a demo or more information from one of our transformer testing experts.
Transformer Winding Resistance
Transformer Screening Tests: It's time for a rethink!