Estimation of paper‐moisture in transformer insulation employing dielectric spectroscopy data

Accurate estimation of paper‐moisture in transformer insulation is necessary for ensuring their satisfactory operation. Paper‐moisture in transformer insulation can be estimated from their corresponding transfer function zero obtained from insulation model that is parameterised using polarisation depolarisation current data. However, paper‐moisture estimated using transfer function zero is less reliable for a new unit. Considering the fact, a method is proposed in this work that can estimate the paper‐moisture with greater accuracy. Instead of using only transfer function zero, tan δ has also been employed for estimating the paper‐moisture. In order to investigate the effectiveness, the proposed technique has first been applied on several test samples in the laboratory. The proposed technique is then applied on few power transformers to estimate their paper‐moisture. Results obtained from the experiment show that this technique can estimate the paper‐moisture content within test samples and power transformer insulation with better accuracy.