Mishra, ShaliniBaral, ArijitMishra, DeepakChakravorti, Sivaji2023-07-202025-04-012023-07-202022-04S. Mishra, A. Baral, D. Mishra and S. Chakravorti, "A Novel Method to Predict Severity of Thermal Aging and Degree of Polymerization for Reliable Diagnosis of Dry-Type Insulation," in IEEE Transactions on Dielectrics and Electrical Insulation, vol. 29, no. 2, pp. 631-640, April 2022, doi: 10.1109/TDEI.2022.3157922.1070-98781558-4135https://ieeexplore.ieee.org/document/9730876https://dspacenew8-imu.refread.com/handle/123456789/2699The effect of thermal aging on Nomex-paper-based vacuum pressure impregnation (VPI) insulation is reported in this article. The frequency-dependent dielectric loss of Nomex-paper-based VPI dry insulation is affected after significant thermal aging. This variation in dielectric loss of the insulation maintains a good correlation with the duration of thermal aging. A new parameter sensitive to the severity of thermal aging is also introduced. To identify the parameter, the excitation voltage waveform and the corresponding insulation response at a given frequency are required. Determining the parameter does not require denoising of recorded waveforms, reducing the overall computational burden. Based on the newly introduced parameter, a cost-effective method is proposed to predict the dielectric loss and degree of polymerization (DP) in a thermally aged VPI-type dry insulation. The proposed method employs the intermediate frequency range and hence does not require time-consuming low-frequency measurements.en-USDegree of polymerization value (DPv)Dry-type transformersFrequency-domain spectroscopy (FDS)Lissajous patternThermal agingArticle