damental understanding of electrical breakdown mechanisms
under different stress situations. The impulse withstand voltage
is normally used as dimensioning criterion for medium voltage
air-insulated systems as flashover mechanisms in air are rapid.
Prediction of withstand voltage relies on streamer inception and
propagation models that are not always sufficiently accurate.
Positive impulse voltage experiments were performed on a rod-
plane gap with a dielectric barrier at different positions parallel
to the ground plane. Streamers initiate from the rod tip and
propagate in the field direction. Charge deposited on the dielectric
surface changes the field situation and can result in a higher
inception voltage. The streamer propagation was recorded with
a fast ICCD camera. Finite element method field simulations
of the background field were used to evaluate the effect of
a barrier surface potential on the streamer inception voltage.
Streamers reach the ground electrode without initiating electrical
breakdown. The discharge activity from the rod was reduced by
deposited charge on the barrier.