Effect of temperature on trap depth formation in multi-layer insulation: Low density polyethylene and fluorinated ethylene propylene

This paper reports on an investigation into space charge formation and decay at dielectric interfaces. In particular, the influence of temperature on the formation of the trap deep has been studied. A multi-dielectrics structure composed of two dielectric films, Low Density Polyethylene (LDPE) and Fluorinated Ethylene Propylene (FEP), was subjected to an electric stress level of +14.3 kV/mm at two temperatures, 40 °C and 60 °C, and space charge measurements were taken using the pulsed electro-acoustic technique. Space charge distributions were investigated for combinations of LDPE/FEP flat specimens. The time dependence of the space charge distribution was subsequently recorded at different temperatures under short circuit (depolarization) conditions. It was found that temperature plays a significant role in space charge dynamics at the dielectric interface, charge mobility, electrical conductivity, filling of the trap, and the formation of the shallow trap.