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High‐field dielectric properties of polyethylene in the high‐temperature region
Author(s) -
Tokoro Tetsuroh,
Tohyama Kazuyuki,
Nagao Masayuki,
Kosaki Masamitsu
Publication year - 1992
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.4391120602
Subject(s) - dielectric , materials science , electric field , dielectric loss , polyethylene , dissipation , dissipation factor , thermal conduction , relaxation (psychology) , waveform , field (mathematics) , conductivity , condensed matter physics , alternating current , electrical resistivity and conductivity , composite material , nuclear magnetic resonance , electrical engineering , optoelectronics , voltage , thermodynamics , chemistry , physics , psychology , social psychology , mathematics , quantum mechanics , pure mathematics , engineering
Nonpolar polymers such as polyethylene or polypropylene are widely used as insulation materials, often under conditions involving strong electric fields and high temperatures. Under these conditions, the conduction loss due to DC‐like carrier transport may give rise to a high‐field AC dissipation factor (tan δ). This paper describes the high‐field dielectric properties of polyethylene films at frequencies from 50 to 400 Hz and temperatures from room temperature to 100°C, as measured with a new type electrode design developed by the authors. In the high‐temperature region, the AC dissipation current waveform at 50 Hz was also measured. At room temperature, the electric‐field dependence of tan δ is almost unaffected by the frequency of the applied field. But at high temperatures and strong electric fields, tan δ tends to have a large field dependence and to be almost inversely proportional to the frequency. Thus the AC conductivity becomes independent of the frequency of the applied field in the region of strong fields and high temperatures. A theoretical analysis shows that the high‐field dielectric loss is governed by two processes, namely, the dielectric relaxation loss inherent to the AC field and the DC‐like carrier transport loss that becomes prominent in the high‐temperature region, where AC dissipation current waveform becomes significantly nonsinusoidal.