Thermal modeling and calibration in (F)LIMM using an external bias field: Theory and experiment

Dielectric materials used widely for their insulating properties, generally undergo high stresses in most industrial environments. For example, space charges can be formed by strong local electric field gradients. This may lead to premature aging of the insulation. The (F)LIMM technique based on a thermal waves source and devoted to space charge studies has recently been extended to on-line measurements in order to account for the actual environment of use. However, prior to any charge profile determination, a calibration of the thermal model describing the shape of the thermal waves produced by the heat source is compulsory. Starting from experimental results and a theoretical analysis the calibration procedure is solved for the new on-line configuration with DC bias. This leads to an optimal data analysis of (F)LIMM current spectra.