77 / 2017-03-06 13:50:35

Influence of Temperature on Frequency Dielectric Spectroscopy of Generator Stator Insulation

Temperature; generator insulation; frequency dielectric spectroscopy (FDS); Cole-Cole model; Arrhenius equationcomponent

To study the influence of temperature on frequency dielectric spectroscopy (FDS) of generator stator insulation. Series of experiments were carried out for stator bars at different temperature firstly. Then the influences of temperature on dielectric spectroscopy of stator bar insulation were analyzed based on a double relaxation Cole-Cole model. Experimental results show that the entire spectrums of ε′ and ε′′ moved to the high frequency, and positive vertical direction. In the range of 10-3~103Hz, the Cole-Cole model can describe the FDS of generator bar insulation accurately. Increasing of the temperature enhanced the strength of interfacial polarization and dipole polarization. The interfacial polarization relaxation time and the direct current conductivity satisfy the Arrhenius equation. According to transition state theory, the value of activation enthalpy is 103.1kJ/mol. The activation entropy increases with the increase of temperature, which indicates the order of the whole system decreases. The decreasing of activation energy indicates all kinds of polarization will completed more easily. So the temperature-dependence of frequency domain dielectric spectroscopy of generator insulation can be descripted by transition state theory.