Surface discharges along polymer foam

The behavior of partial discharges (PD) along a polymer foam insulator in air is investigated at 50 Hz AC voltage. The results were compared to the PD behavior along other solid/air interfaces. The PD inception voltage depends on the dielectric constant of the solid material. It was highest for the foam/air interface. Further, the effect of the dielectric constant on the PD mechanism is investigated. A qualitative explanation is provided.