Characteristic Evaluation of BOPP Capacitor after Winding Process with Mechanical Stress

Biaxially oriented polypropylene (BOPP) film capacitor is one of the key equipment in converter valve halls of HVDC transmission systems. Bulk capacitors in HVDC transmission usually consist of capacitor elements made by winding a metallized film. The capacitor winding process is performed by winding a metallized film on a reel and setting different winding mechanical stresses according to performance requirements. The difference in mechanical stress will seriously affect the characteristic indictors such as clearing energy, breakdown field strength, and dielectric loss of metallized film capacitors, so the selection of appropriate mechanical pressure is extremely critical to the safe operation and reliability of the capacitor.