Acceptance Criteria for Dissipation Factor of a Coil/bar
Acceptance Criteria for Dissipation Factor of a Coil/bar
(OP)
Hi,
IEEE has a standard (recommended practice) for measurement of power-factor tip-up of electric machinery stator coil insulation (IEEE 286-2000). Test methods are described there but no acceptance criteria is recommended. I was wonder if anyone can provide me an acceptance criteria for dissipation factor(power-factor) for new coils (at low voltages(0.1-.2Un))?
Thanks
IEEE has a standard (recommended practice) for measurement of power-factor tip-up of electric machinery stator coil insulation (IEEE 286-2000). Test methods are described there but no acceptance criteria is recommended. I was wonder if anyone can provide me an acceptance criteria for dissipation factor(power-factor) for new coils (at low voltages(0.1-.2Un))?
Thanks






RE: Acceptance Criteria for Dissipation Factor of a Coil/bar
RE: Acceptance Criteria for Dissipation Factor of a Coil/bar
Thank for reply. I also heard about 1% criteria for epoxy/mica coils but I don`t have any reference for that. I could not find it (or any criteria) at IEEE286. Could you please let me know any reference or standard for this value?
The another question is: we have a coil with dissipation factor at low voltages (slightly)higher than 1%, but with good tip-up and PD results. Is it Ok or it should be rejected?
RE: Acceptance Criteria for Dissipation Factor of a Coil/bar
"The expected power factor and power factor tip-up vary with the type and age of the insulation system. The type of insulation system shall be identified, i.e., asphalt-mica, epoxy-mica, or polyester-mica. The power factor is also affected by the temperature of the insulation, and accordingly, periodic tests should be performed at similar temperatures. The power factor tip-up is also affected by the atmosphere during the test, e.g., air versus sealed with rated hydrogen pressure."
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It depends:
"The power-factor-voltage characteristic (power- factor tip-up) is used primarily as a quality-control criterion in manufacturing. It is sometimes used as an acceptance test on individual coils. Power-factor tip-up has been used as a maintenance test because a change in the tip-up value over a period of time is an indication of change of condition of the coil insulation. "
Doble has a database of test results by machine voltage, insulation type, cooling etc. They provide periodic summaries of that database. Example "UPDATE OF THE POWER FACTOR DATABASE FOR GENERATOR STATOR INSULATION (A REVIEW), dated 2004, by Eileen M. Duarte, Doble Engineering Company"
Doble information is available only to Doble clients.
Many user's have adopted limits such as 0.5% power factor or 1% tip-up in their specifications for either new coils or assembled winding. It is then up to the supplier to justify deviations from that specification.
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RE: Acceptance Criteria for Dissipation Factor of a Coil/bar