IEC 60247 pdf download Insulating liquids – Measurement of relative permittivity, dielectric dissipation factor (tan δ δ ) and d.c. resistivity
This International standard describes methods for the determination of the dielectric dissipationfactor (tan o), relative permittivity and d.c. resistivity of any insulating liquid material at the testtemperature.
The methods are primarily intended for making reference tests on unused liquids. They canalso be applied to liquids in service in transformers,cables and other electrical apparatus.However the method is applicable to a single phase liquid only. When it is desired to makeroutine determinations,simplified procedures,as described in Annex C, may be adopted.
With insulating liquids other than hydrocarbons，alternative cleaning procedures may berequired.
The following referenced documents are indispensable for the application of this document. Fordated references, only the edition cited applies.For undated references, the latest edition ofthe referenced document (including any amendments) applies.
IEC 60093，Methods of test for volume resistivity and surface resistivity of solid electricalinsulating materials
IEC 60250，Recommended methods for the determination of the permittivity and dielectricdissipation factor of electrical insulating materials at power,audio and radio frequenciesincluding metre wavelengths
IEC60475，Method of sampling liquid dielectrics
IEC 61620，Insulating liquids – Determination of the dielectric dissipation factor by measure-ment of the conductance and capacitance – Test method
3Terms and definitions
For the purposes of this document,the following terms and definitions apply.
the relative permittivity of an insulating material is the ratio of capacitance C, of a capacitor inwhich the space between and around the electrodes is entirely and exclusively filled with theinsulating material in question, to the capacitance C, of the same configuration of electrodes invacuum.
The capacitance C of the configuration of electrodes in air can normally be used instead of Coto determine the relative permittivity with sufficient accuracy
dielectric dissipation factor (tan 8DDF
dielectric dissipation factor，DDF, (tan 6) of an insulating material is the tangent of the lossangle.
The loss angle is the angle by which the phase difference between applied voltage and theresulting current deviates from n/2 rad when the dielectric of the capacitor consists exclusivelyof the insulating material
NOTE For practical purposes, measured values below 0,005 for tan b and power factor are essentially the same.A simple conversion can be used to convert one to the other. The power factor is the sine of the loss angle and therelationship between power factor and dielectric dissipation factor can be expressed as follows: