Partial-Discharge Magnitude Estimation With Three-Dimensional Finite-Element Methods

Prediction of partial-discharge (PD) magnitude for ellipsoidal and spheroidal cavities in bulk insulation is easily addressed using axisymmetric 2-D finite-element methods (FEM), with the cavity on-axis. The introduction of an arbitrary defect even within an axisymmetric device breaks the 2-D symmetry, which makes prediction of PD magnitudes impossible without the use of 3-D FEM. A separable connector with tracks along various interfaces was modeled using 3-D FEM, and the apparent PD magnitude was estimated by multiplying the change in capacitance during discharges and the PD extinction voltage. Experimental PD measurements for the separable connector show good agreement with predictions. Since failure of separable connectors can cause significant damage, knowledge of the PD magnitude as a function of defect severity is useful to investigate diagnostics for defective connectors.