Dielectric properties and space charge formation in polypropylene film up to AC breakdown

Non-liner behavior of dissipation current that flows in polymer materials contains much information about dielectric property under AC high field application. Recently, the properties were evaluated by using film sample of non-polar dielectric materials. AC dissipation current measurement shows the formation of AC space charge near electrodes under AC high field application. However, the direct measurement of AC space charge distribution is not so easy due to the resolution limit of the measurements. We measured high field dielectric properties of PP film up to breakdown by using short time AC ramp voltage application method. Based on the experimental results, AC conduction mechanism, AC breakdown mechanism and the space charge behavior under AC high field were discussed.