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Partial Discharge Part XXV: Calibration of PD Measurements for
Motor and Generator Windings - Why it Can't be Done by Dr. G C Stone - Iris
Power Engineering Inc, Jan/Feb 1998 - Vol 14, No 1, IEEE Electrical
Insulation Magazine.
Key Words: partial discharge, windings, ageing, rotating machine,
diagnosis, stator
"Perhaps the most widespread application of PD testing is for
detecting deterioration in rotating machines."
Reviewer's summary: Introduction - reviews the history of PD as
applied to large rotating machines; PD Measurement Quantities - discusses
the development of the use of charge (pC) as the measure of PD; PD as a
Symptom - covers the differences in using PD for assessing windings vs.
cables or switchgear and its usefulness in monitoring changes toward
failure of windings; Effect of Winding Characteristics on PD Magnitudes -
reviews the difficulty of making capacitance measurements in the highly
inductive windings and discussed some important measurement issues;
Conclusions - 1) PD measurements of stator windings should not be reported
in absolute terms, 2) comparison of measurements between different model of
measuring instruments is is inconclusive, 3) the complexity of the winding
modifies the PD pulses and interferes in getting and interpreting the
results, 4) in windings the PD measurement is clouded because several
failure mechanisms operate simultaneously and all add to the measurement so
that the insulation failure cannot easily be separated from the others; 5)
interpretation of PD results is comparative and will show further
deterioration of a winding, similar measurements across similar machines
can be compared but this works better if there is a large data base of
these measurements.
References: a short, related set of references is included.
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Peter E Perkins
Principal Product Safety Consultant
Tigard, ORe 97281-3427
+1/503/452-1201 phone/fax
[email protected] email
visit our website:
http://ourworld.compuserve.com/homepages/peperkins
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