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Expanding the Diagnostic Impact of Power Factor Testing - Interpretation of Narrow Band Dielectric F

Expanding the Diagnostic Impact of Power Factor Testing - Interpretation of Narrow Band Dielectric Frequency Response

Transformers Magazine, Vol 6, Issue 6

The Narrow Band Dielectric Frequen-cy Response (NBDFR) test method consists of a series of power factor measurements ranging from 1 to 1000 hertz. This aggregate of the CHL (pri-mary to secondary) measurements constitutes the dielectric response of the test specimen. The subsequent evaluation consists of a geometric analysis of a plot where the mea-sured power factors and correspond-ing frequencies are graphed. As an insulation system ages, the response migrates towards the high frequency end of the plot. When the frequency corresponding to the lowest magni-tude within the response (the trough) is used as a reference point, the move-ment of the response may be quanti-fied; enabling the transformer may be classified in terms of condition.

Authors Robert Breazeal and Dinesh Chhajer
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