The role of polarization in the breakdown of an air gap with barrier

It is shown that the inhomogeneous polarization of an insulation gap with barrier in an electrical field due to a sharp change in the permittivity and/or conductivity at the interface of `basic dielectric-barrier' is one of possible reasons of the so-called barrier effect in dielectrics. The influence of the preliminary polarization of thin polyethylene terephthalate barriers on the breakdown voltage of an air gap with a needle-plane configuration under ac and dc voltage is determined.