What Is a Winding Resistance Test?

Published 27 Aug 2026Updated 27 Aug 20265 min readIntermediateTesting
Quick answer — The winding resistance test measures the DC resistance of each winding by passing a DC current and reading the voltage, so the resistance (V/I) is obtained. It detects a poor joint, a loose or broken connection, or a turn fault by comparing the phases or against a baseline, and it is also used to derive the winding temperature in the temperature-rise test.
Contents
What is a transformer winding resistance test?

What it does

A DC current is applied and the voltage drop measured, giving the resistance of the winding and any connected leads/terminals.

Why it is done

It checks the winding and connections for a problem: a higher-than-expected or unequal phase resistance points to a loose or broken joint, or a winding fault.

Also used for temperature

The change in resistance with the temperature is used to calculate the winding temperature in the temperature-rise (heat run) test.

References & standards

Related

Book seriesAcademy

Related manufacturers

Prolec GE (GE Vernova) · Prolec GE Waukesha · Hitachi Energy USA · Siemens Energy · Eaton · Virginia Transformer Corp

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Technical content is prepared from engineering references, standards frameworks, manufacturer documentation and industry sources. Contractual or compliance decisions should refer to current official standards. TransformerPath Technical Editorial.
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