Effect of partial discharges on thermal breakdown of oil‐impregnated paper

Abstract

In this paper, we investigate the effect of partial discharges (PDs) on the thermal breakdown voltage of oil-impregnated paper (OIP). A disk-shaped cavity in a stack of paper sheets formed the PD source. The paper sample was exposed to PDs for 18 h. Dielectric spectroscopy measurements were performed on the samples before and after exposure to PD activity. The dielectric spectroscopy results showed a big change in the real and imaginary part of the permittivity. These results were used to calculate the activation energy and heat losses inside the insulation. In order to investigate the possibility of thermal breakdown in the system, the OIP system was simulated by using the FEM software COMSOL Multiphysics. The heat produced by PD pulses and dielectric losses was considered in the simulation. The results show that for the OIP insulation, PD activity can reduce the thermal breakdown voltage by a factor up to 4 times.

Optical Detection Method for Partial Discharge of Printed Circuit Boards in Electrified Aircraft Under Various Pressures and Voltages

“…where ε r,app is the apparent relative permittivity, ε r is the imaginary part of complex relative permittivity, ω is the angular frequency, σ is the conductivity, P is the dielectric loss, and E is the electric field [24]. From ( 3) and ( 4), it can be seen that the dielectric loss increases with the increase of voltage frequency when the electric field strength is constant.…”