Evaluation of ethylene propylene rubber as an electrical insulation material of superconducting cable

The mechanical and electrical properties of ethylene propylene rubber (EPR) pieces were made in comparison with polyethylene (PE) in the cryogenic temperature region to examine the possibility for use in solid electrical insulation material of superconducting cables. The mechanical properties of EPR are preferable to those of PE because of its low shrinkage. The electric strength and dielectric loss tangent of EPR are comparable to those of PE at liquid helium temperature. Based on these encouraging results, an extruded EPR-insulated cable was fabricated and its 15 m length was cooled down to liquid helium temperature successfully. A partial discharge experiment at the temperature showed good electrical characteristics.<
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