Premium
Tan δ of ethylene‐propylene rubber in cryogenic temperature region–effects of additives and sample thickness
Author(s) -
Mizuno Yukio,
Mitsuyama Yasuichi,
Minoda Atsushi,
Nagao Masayuki,
Kosaki Masamitsu
Publication year - 1996
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.4391160201
Subject(s) - ethylene propylene rubber , materials science , composite material , dielectric loss , electron paramagnetic resonance , conductor , dielectric , electromagnetic shielding , polymer , natural rubber , superconductivity , nuclear magnetic resonance , condensed matter physics , optoelectronics , copolymer , physics
The authors have been developing extruded polymer insulated superconducting power cables. Dielectric loss in electrical insulation cannot be ignored in superconducting cables since conductor loss in the cables is minimal. Studies so far show that ethylene‐propylene rubber (EPR) is suitable as an electrical insulating material in the extruded polymer insulated superconducting cable design because it demonstrates excellent mechanical and relatively good electrical qualities at a cryogenic temperature. Widely used EPR includes some kinds of additives; however, their effect on tan δ of EPR at cryogenic temperature remains unknown. The effect of additives such as crosslinking agent and fillers on tan δ of EPR was examined at temperatures of between 4.2 K and 300 K. Thickness dependence of tan δ was also measured using EPR films of different thickness and an extruded EPR insulated cable sample. The results show that additives increase tan δ of relatively thin films of EPR even in the cryogenic temperature region; however, they do not have an intolerable dielectric loss in comparison with conductor loss and heat inflow of the superconducting cable. The remedy to tan δ increase due to the polymer contraction relative to shielding wires has been established.