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|Title:||Electric field criteria for charge packet formation and movement in XLPE.|
Dissado, Len A.
Fothergill, John C.
|Publisher:||Institute of Electrical and Electronics Engineers (IEEE)|
|Citation:||IEEE Transactions on Dielectrics and Electrical Insulation, 2001, 8 (6), pp. 859-866.|
|Abstract:||The formation of space charge packets in XLPE (Cross-linked polyethylene) tapes from unaged cable insulation has been studied utilising the pulsed electro-acoustic (PEA) technique. The 150 m thick sheets were studied under constant applied dc field of 120 kV/mm at a temperature of 20 C for a period of 48 hours. After an inception period of about 3.5 hours, during which heterocharge accumulates at the anode and increases the local field there, a sequence of positive charge packets were observed to transit the sample starting from near the anode. Calculation of the internal field showed that the packets required a field of 140 kV/mm for their initiation. Reduction of the applied field step-wise from 120 kV/mm to 80 kV/mm indicated that the charge packet would keep moving as long as the local field at its front exceeded 100 kV/mm, but with a reducing magnitude. A return to an applied field of 120 kV/mm confirmed that the local field required to initiate a new packet was in excess of 135 kV/mm. The results are discussed in terms of current theories of charge packet formation. The first packet appears to be a moving front of field ionisation. The generation of subsequent packets is governed by the field at the anode and the balance of charge injection and extraction process, which occur there. The nature of the negative charges produced at the ionisation front is not clear, but they are unlikely to be electrons.|
|Rights:||This is the author's final draft of the paper published as IEEE Transactions on Dielectrics and Electrical Insulation, 2001, 8 (6), pp. 859-866. Copyright © 2001 IEEE. The final version is available from http://ieeexplore.ieee.org/. Doi: 10.1109/94.971438. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Leicester’s products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to firstname.lastname@example.org. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.|
|Appears in Collections:||Published Articles, Dept. of Engineering|
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