An online phase-to-phase insulation diagnostic method for multi-phase Wye winding machine

Leakage current is an effective indicator detecting the machine phase-to-phase (PP) insulation. In Y-connected windings, the inability to measure the leakage current of each phase prevents the assessment of the aging level of the PP insulation. This paper introduces an online PP leakage current measurement method in a six-phase machine utilizing the feature of the winding structure. And the analysis of voltage distribution indicates that the insulation condition of the machine can be assessed using the PP voltage and leakage current at a particular frequency. Additionally, the carrier phase-shifted technology is employed to calculate the PP equivalent capacitance. Considering the extended insulation aging period, the capacitor is connected between the different windings to artificially induce PP insulation aging. The experimental results demonstrate the effective calculation of the PP equivalent capacitance using the proposed method.