DIELECTRIC DISSIPATION FACTOR 1

[Marvie]

Anyone out there who knows of a site that intensively covers the area of oil dielectric dissipation factor (tan delta)?

 

[edison123]

The book, Electrical Measurements by E W Golding covers this test extensively including the theory and test set up.

Muthu

http://www.edison.co.in

 

[electricpete]

http://www.usbr.gov/power/data/fist/fist3_31/fist3-31.pdf

6.1.7

Oil Power Factor. Power factor indicates the dielectric loss (leakage current associated with watts loss) of the oil. This test can be performed by DGA laboratories. It may also be done by Doble testing in the field. A high power factor indicates deterioration and/or contamination from byproducts such as water, carbon, or other conducting particles, including metal soaps caused by acids attacking transformer metals, and products of oxidation. DGA labs normally test oil power factor at 25 EC and 100 EC. Information in Doble Engineering Company Reference Book on Insulating Liquids and Gases RBIL-391, 1993 [10] indicates the in-service limit for power factor is less than 0.5% at 25 EC. If the power factor is greater than 0.5% and less than 1.0%, further investigation is required; the oil may require replacement or Fuller’s earth filtering. If the power factor is greater than 1.0% at 25 EC, the oil may cause failure of the transformer; replacement or reclaiming of the oil is required immediately. Above 2%, oil should be removed from service and replaced because equipment failure is imminent. The oil cannot be reclaimed.

That's not exactly extensive but I assume it is addressing the area of your question: power factor testing of the oil itself.

As far as I know, the advantge of this test is that it can easily be done quickly with immediate results in the field with a power factor test set and special cup. But if you send it to the lab for Dielectric breakdown and other standard tests, you'll get a lot better diagnostic... (at least that's what I have inferred... labs don't often package power factor into their transformer standard packages... but field testing companies do.)

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[electricpete]

Clarification:
"(at least that's what I have inferred... oil analysis labs don't often package oilpower factor into their transformer standard oil analysis packages... but field testing companies do.)"

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