Study of Trapping Process in BOPP by Coupled Space Charge and Photo-stimulated Discharge Techniques

The global market of biaxially oriented polypropylene (BOPP) film capacitors is growing constantly, as part of energy transition needs. The formation of physical or chemical defects in BOPP can lead to insulator failure due to charge build-up. It is therefore necessary to determine the amount and location of charges and to evaluate the trap energy depths to better understand conduction and aging phenomena. A test bench allowing to do combined space charge measurements by the laser intensity modulation method (LIMM) and optically excited current acquisitions by the photo-stimulated discharge method (PSD) is used to monitor charge accumulation, trap population and de-trapping scenarios. In this investigation, homocharge enhancement near the probed electrode is evidenced in a blank sample. Under light exposure for PSD measurements, charge de-trapping or reactions of BOPP additives modify the charging process.