Title :
Space charge formation and its modified electric field under applied voltage reversal and temperature gradient in XLPE cable
Author :
Fu, M. ; Dissado, L.A. ; Chen, G. ; Fothergill, J.C.
Author_Institution :
Dept. of Eng., Univ. of Leicester, Leicester
fDate :
6/1/2008 12:00:00 AM
Abstract :
The results of space charge evolution in cross-linked polyethylene power cables under dc electrical field at a uniform temperature and during external voltage polarity reversal are presented in the paper. A mirror image charge distribution was observed in the steady state, but the pre-existing field altered the way in which the steady state charge distribution was formed from that obtaining when the cable was first polarized. Polarity reversing charge was generated in the middle of the insulation and moved towards the appropriate electrodes under the influence of a field in excess of the maximum applied field. Our results show that the mirror effect is a steady state effect that is due to cross-interface currents that depend only on the interface field and not its polarity. Measurements on cable sections with an elevated mean temperature and temperature gradient show that the interface currents are temperature dependent, and that differences between the activation energies of the interface and bulk currents can eliminate, and possibly even invert the polarity of the space charge distribution.
Keywords :
electric fields; power cables; space charge; XLPE cable; activation energies; bulk currents; cross-interface currents; cross-linked polyethylene power cables; dc electrical field; elevated mean temperature; external voltage polarity reversal; interface currents; mirror image charge distribution; polarity reversing charge; space charge formation; steady state charge distribution; temperature gradient; Mirrors; Polarization; Polyethylene; Power cable insulation; Power cables; Space charge; Steady-state; Temperature dependence; Temperature distribution; Voltage;
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on
DOI :
10.1109/TDEI.2008.4543123