Characterization in Medium Voltage Stator Coils Using Dielectric Frequency Domain Spectroscopy

The Dielectric Frequency Domain Spectroscopy (FDS) is a widely used test to estimate the moisture content in power transformers. However, this diagnostic technique has potential to be utilized in different applications where the moisture level estimation is a critical parameter. In this paper, the FDS has been tested for moisture characterization in stator-winding coils. The main idea is being able to evaluate the moisture content during stator winding coil manufacturing. The laboratory test described in this paper has been carried out by moistened and de-moistened controlled laboratory tests, using FDS sweeps and measuring the moisture content by the coil weight.