Effect of Temperature on the Characteristics of Frequency Domain Spectroscopy of Generator Stator Insulation

In order to better apply frequency domain spectroscopy(FDS) in assessment of generator stator insulation condition, the frequency domain spectroscopy of the stator bar insulation were tested at different temperatures. The variation law of dielectric loss factor tan delta, complex permittivity epsilon and electrical conductivity sigma of the bar insulation with temperature and electric field frequency were analyzed. The insulation properties of bar influenced by temperature were further discussed in this paper, a normalization method of date at different temperatures was introduced. The results show that the permittivity of the generator stator bar insulation affected by temperature is sensitive at low frequency, and the geometric capacitance C shows an exponential relationship with temperature T. epsilon'(-f)(T) and tan delta-(f) (T) have an exponential relationship with C. This study can eliminate the influence of environment temperature on FDS measurements, and makes it better to assess the state of generator stator insulation with FDS.