Dielectric Characteristics of EPR for 66 kV-Class Power Leads of High-Tc Superconducting Fault Current Limiter

A 66 kV-class power lead insulation system has been developed for high-Tc superconducting fault current limiters (SCFCL). The power leads are insulated with ethylene-propylene rubber without organic filler, and have excellent crack resistance. This system was evaluated by an insulation model and was shown to have strong enough electrical insulation properties for 66 kV-class equipment. To minimize insulation layer thickness, the dielectric characteristics of this EPR were investigated in detail. The specimens were made 0.3-10 mm thick: near the thickness of an actual power lead insulation layer. The breakdown stress was measured at room temperature and at liquid nitrogen temperature. The V-t characteristic was also measured. Based on the study, the power lead insulation model was constructed and its electrical insulation properties were evaluated