A smart way to minimize test time for transformer dielectric measurements

Dielectric response measurements for the moisture and oil conductivity assessment of transformers are well understood, internationally accepted and growing in use. Of the two principal dielectric response methods, an AC method called Dielectric Frequency Response (DFR, also Frequency-Domain Spectroscopy, FDS) is preferred due to its robustness against noise. The time requirement of a DFR measurement is lengthy compared to that of other electrical test methods. An earlier approach to accelerate test time combined DC (time domain) and AC (frequency domain) test methods. This article discusses the limitations inherent to that approach and presents today’s multifrequency test solution that minimizes test time for DFR measurements without compromising accuracy