Packet-like space-charge behavior and conduction current in polyethylene for cable insulation

Kon, Hiroyuki; Suzuoki, Yasuo; Mizutani, Teruyoshi; Yoshifuji, N.

doi:10.1109/iseim.1995.496554

Cited by 4 publications

(7 citation statements)

References 3 publications

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“…In our case the threshold field is the minimum packet onset field obtained over experiments lasting up to 48 hours during which the onset field steadily declined from a high of 210 kV/mm down to 140 kV/mm. It is noticeable that the experimental onset fields reported in [7] diminish over a period of 4800s (80 minutes) from 250 kV/mm to around 170 kV/mm, and it may be that a longer experiment would see them approach our lower value.…”

Section: Discussionmentioning

confidence: 72%

Electric field criteria for charge packet formation and movement in XLPE

See

Dissado

Fothergill

2001

IEEE Trans. Dielect. Electr. Insul.

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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. This is shown as a moving image at the following web site: . 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 See, Dissado and Fothergill 9/16/08 2:31 PM 2 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.

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Section: Discussionmentioning

confidence: 72%

Electric field criteria for charge packet formation and movement in XLPE

See

Dissado

Fothergill

2001

IEEE Trans. Dielect. Electr. Insul.

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“…In fact this sequence is similar to the experimental results reported in [7]. A further point to note is that the step-change experiment shows that the packet once formed can retain its integrity as a packet, but with a reduced magnitude, even when the field at its front drops to 100kV/mm.…”

supporting

confidence: 86%

“…Injection of positive space charge is attested by the presence of electroluminescence but the positive space charge moves even slower than the negative charge and its injection is very weak. For this reason charge packets cannot develop in the middle of the sample such as occurs in the model of [8], and the experiments of [7].…”

Section: Discussionmentioning

confidence: 99%

“…In these circumstances space charge is observed to cross the insulation in the form of a packet rather than through the steady advance of a charge front. Such packets have been observed both in cable insulation [5,6], and in thin films (see for example [7,8,9]), and are now a widely accepted phenomenon in polymers. Since they occur at high fields before an electric failure occurs they are of interest as a possible pre-breakdown phenomenon.…”

Section: Introductionmentioning

confidence: 97%

“…In one case [6] the packet is formed by injected charges and moves across the sample as a packet of excess charge carriers. Usually these packets are small in magnitude (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) ) and spread out as the packet moves so that the packet loses its identity as it crosses the sample. This type of packet can only be re-created a few times.…”

Section: Introductionmentioning

confidence: 99%

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Electric field requirements for charge packet generation and movement in XLPE

See

Dissado²,

Fothergill³

ICSD'01. Proceedings of the 20001 IEEE 7th International Conference on Solid Dielectrics (Cat. No.01CH37117)

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This is the unspecified version of the paper.This version of the publication may differ from the final published version. Permanent repository link ABSTRACTThe 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. This is shown as a moving image at the following web site: . 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 See, Dissado and Fothergill 9/16/08 2:31 PM 2 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.

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Space charge behavior in XLPE cable insulation under 0.2-1.2 MV/cm dc fields

Hozumi

Takeda

Suzuki

et al. 1998

IEEE Trans. Dielect. Electr. Insul.

171

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This report deals with space charge behavior in PE (polyethylene) under dc fields. Direct observation of time-dependent space charge profiles in 3-mm thick XLPE (crosslinked low-density polyethylene) cable insulation under dc electric fields was performed using the pulsed electroacoustic method. Stable hetero charges were formed when the field was as low as 0.2 MV/cm, and intermittent generation of packet shaped space charges and their propagation through the insulation were observed when the field was as high as 0.7 MVlcm. These phenomena were reproduced in sheet specimens of XLPE and LDPE (low-density polyethylene). It was found that hetero charges resulted from heat treatment of the XLPE specimen containing antioxidant and acetophenone, which is one of the crosslinking by-products, suggesting dissociation of the antioxidant through solvation at high temperature by acetophenone. The packet charges were easily detected when acetophenone was diffused into the LDPE specimen. However, uniformity of acetophenone distribution prevented the packet charge generation. It is suggested on the basis of several experimental results that local ionization of impurities in the insulation through solvation by acetophenone takes place assisted by high field and leads to the packet charge generation. A numerical simulation was carried out based on the above model.

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Packet-like space-charge behavior and conduction current in polyethylene for cable insulation

Cited by 4 publications

References 3 publications

Electric field criteria for charge packet formation and movement in XLPE

Electric field criteria for charge packet formation and movement in XLPE

Electric field requirements for charge packet generation and movement in XLPE

Space charge behavior in XLPE cable insulation under 0.2-1.2 MV/cm dc fields

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