Abstract
The article depicts the results of comparing the classical method and the developed method to determine insulation parameters in ungrounded AC systems. The developed method is based on measuring magnitudes of zero-sequence voltage, phase-to-earth voltage, and phase angles of the phase-to-earth voltage vector, and the zero-sequence voltage vector before and after connecting additional susceptance between the phase and earth. This article explains the sequence of measurements for the two methods in the laboratory conditions, where the results of the comparison confirm that the values of RMS errors and relative RMS errors of the developed and classical methods have good convergence. An experimental study of the developed method for determining insulation parameters demonstrates satisfactory accuracy and is a safer method compared to the classical method due to the absence of a single-phase earth fault.