Feasibility of a universal approach for temperature correction in frequency domain spectroscopy of transformer insulation

Correction for Polarization Current Curve of Polymer Insulation Materials in Transformers Considering the Temperature and Moisture Effects

“…The PDC curves of the oil-immersed polymer pressboards tested at different temperatures can be shifted to coincidence by a series of the movement (horizontal and vertical). The process of moving the measured PDC curve to the reference temperature is called the construction process of the master curve, and the PDC curve shifted to the reference temperature is defined as the master curve [19,20]. The degree of movement of the curve can be expressed as the time-shift factor and the amplitude-shift factor, respectively.…”

“…Saha and Purkait [14] investigated the PDC curves at different temperatures to indicate that the polarization time will be shortened as the temperature increase. In response to the above research results, the master curve technique based on the time-temperature superposition theory is used as an available model to correct the temperature effect of the transformer polymer insulation materials, which provides a novel idea for related research [15][16][17][18][19][20]. However, the temperature effect is considered as the single factor affecting the PDC test results in the existing research, which ignores the fact that moisture content is also an important factor affecting the polarization data of polymer material.…”

A Modified Aging Kinetics Model for Aging Condition Prediction of Transformer Polymer Insulation by Employing the Frequency Domain Spectroscopy

“…The simultaneity of Equations (1) and (7) provide an expression characterizing the rate of decrease in the DP value of polymer insulation materials.…”

“…In view of the above issues, the existing researches reveal that dielectric frequency response might be used as an available approach to achieve the moisture analysis of polymer insulation materials [2,6,7,10,11]. Provided that the relevant parameter extracted from the analysis of FDS can be adopted to reflect the moisture content inside the cellulose insulation, the quantitative relationship between the extracted frequency dielectric response parameter and either ω DP (mc%) or k DP (mc%) can be established.…”

“…Existing researches show that the degree of polymerization (DP) can be serviced as the most direct and effective indicator for reflecting the aging condition (mechanical strength) of polymer insulation [1][2][3]. Reviewing the published researches, we found out that the method for predicting (or measuring) the DP value of transformer polymer insulation consists of several prevailing approaches, such as the direct method (viscosity testing) [4] and indirect methods (including the Frequency Dielectric Spectroscopy (FDS) [5][6][7][8][9] technique, aging kinetics model [10][11][12], etc.). Although the viscosity test method is accurate enough, it is not appropriate for analyzing the field equipment due to its destructiveness.…”