Electric characterization of films peeled from the insulation of extruded HVDC cables

Zebouchi, N.; Carstensen, P.; Farkas, A.A.; Campus, A.; Nilsson, U.H.

doi:10.1109/ceidp.2005.1560625

Cited by 9 publications

(6 citation statements)

References 6 publications

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“…In majority of existing publications, the studies were conducted on very thin 100-200 um thick films obtained from cable insulation by means of peeling [4][10][11] [12]. The advantage of this method is that using a short piece of cable, it is possible to obtain samples from different locations of the insulation; besides, by voltage levels of few kV, electric fields representative to HVDC cables can be achieved.…”

Section: Sample Preparation Methodsmentioning

confidence: 99%

“…Since different parts of cable insulation experience different thermal and chemical conditions during the extrusion, vulcanization, heat treatment, and even tests, the conductivity of insulation is not homogenous. In XLPE insulated cables, the temperature gradient during crosslinking, may affect the crosslinking reactions and also the resulting morphology in the inner and outer parts of insulation which in its turn affects conductivity of the insulation [4]. The XLPE cables usually undergo a heat treatment step, also called degassing, to remove the volatile chemicals produced from the decomposition of peroxides.…”

Section: Introductionmentioning

confidence: 99%

“…Space charge measurement using PEA technique can provide further insight into the distribution of conductivity in the insulation but it can be hard to achieve reliable PEA measurements in cables with thick insulation especially when temperature gradients exist throughout the insulation. Considering the challenges above, since long, researchers have been interesting in testing samples obtained from full-scale cables [4] [10] [11] [12]. In this way, while enjoying the advantage of small scale lab condition tests, one obtains representative data from the actual cable insulation.…”

Section: Introductionmentioning

confidence: 99%

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Conductivity measurement of plaque samples obtained from the insulation of high voltage extruded cables

Ghorbani¹,

Farkas²,

Hulden³

2017

NORD-IS

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Good understanding of insulation conductivity is of great importance in development and design of high voltage DC cables. Conductivity of polymeric insulation materials is a property which is quite sensitive to many parameters such as temperature, electric field, chemical composition, thermal history, morphology, etc. Therefore, due to different process history, the results obtained from pressed plaques are not necessarily representative of the insulation behavior in an extruded cable. A method was developed to obtain samples from HV cable in form of plaques with a thicknesses up to a few millimeters. Plaque samples were extracted from two cables, their conductivity at high field was measured and compared to those obtained from fullscale tests; the results, confirm a very good agreement between the small scale and full-scale measurements; this hints to a promising prospect for such small scale characterization techniques.

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Section: Sample Preparation Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Conductivity measurement of plaque samples obtained from the insulation of high voltage extruded cables

Ghorbani¹,

Farkas²,

Hulden³

2017

NORD-IS

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“…Actually, the semi-conductive shielding layer lying between the conductive wire core and the insulation layer plays an important role in producing uniform high electric fields and preventing charge injection to the insulation layer, as the inevitable path for the migrating charges from the conductive wire core to the insulation layer. Usually, the traditional semi-conductive materials are manufactured with carbon black (CB) as the conductive particles, low-density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) as polymer matrix [13][14][15][16][17][18]. In the actual application, the traditional semi-conductive composites often exhibit the positive temperature coefficient effect, as the resistivity of the semi-conductive composites increase as the temperature rises, increasing sharply near the melting region of the polymer, which is the positive temperature coefficient (PTC) effect [19,20].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of a Novel Semi-Conductive Composites Doping with La0.8Sr0.2MnO3 for Excellent Electric Performance for HVDC Cable

et al. 2020

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The semi-conductive layer located between the wire core and the insulation layer in high voltage direct current (HVDC) cable plays a vital role in uniform electric field and affecting space charges behaviors. In this work, the research idea of adding ionic conductive particles to semi-conductive materials to improve the conductive network and reduce the energy of the moving charge inside it and to suppress charge injection was proposed. Semi-conductive composites doped with different La0.8Sr0.2MnO3 (LSM) contents were prepared. Resistivity at different temperatures was measured to investigate the positive temperature coefficient (PTC) effect. Pulse electro-acoustic (PEA) method and thermal-stimulation depolarization currents (TSDC) tests of the insulation layers were carried out. From the results, space charge distribution and TSDC currents in the insulation samples were analyzed to evaluate the inhibitory effect on space charge injection. When LSM content is 6 wt. %, the experimental results show that the PTC effect of the specimen and charge injection are both being suppressed significantly. The maximum resistivity of it is decreased by 53.3% and the insulation sample has the smallest charge amount, 1.85 × 10−7 C under 10 kV/mm—decreased by 40%, 3.6 × 10−7 C under 20 kV/mm—decreased by 45%, and 6.42 × 10−7 C under 30 kV/mm—decreased by 26%. When the LSM content reaches 10 wt. %, the suppression effect on the PTC effect and the charge injection are both weakened, owing to the agglomeration of the conductive particles inside the composites which leads to the interface electric field distortion and results in charge injection enhancement.

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“…The semi-conductive layer is an essential component of high voltage direct current (HVDC) cables and plays an important role in the uniform electric field and makes the conductor wire core and the insulation layer connect tightly [1,2,3,4,5,6,7]. The semi-conductive composites are mainly composed of ethylene-vinyl acetate copolymer (EVA), low-density polyethylene (LDPE) and carbon black (CB).…”

Section: Introductionmentioning

confidence: 99%

Charge Injection Characteristics of Semi-Conductive Composites with Carbon Black-Polymer for HVDC Cable

et al. 2019

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Semi-conductive composites composed of carbon black-polymer play an important role in uniform electric field in high voltage direct current (HVDC) cable. They also affect space charge behaviors in the insulation material. However, the charge injection characteristics of semi-conductive composites are not detailed. In this work, the electrode structure of ‘Semi-conductive composites- Insulation material- Metal bottom’ (S-I-M) is proposed, and the currents formed by injected charges from semi-conductive composites are characterized by the thermally stimulated depolarization current (TSDC) method. Further, the experimental results based on the structure of S-I-M are compared with the traditional electrode structure of M-I-M (Metal upper electrode- Insulation material- Metal bottom electrode) and the simplified cable electrode structure of MS-I-M (Metal upper electrode-Semi-conductive electrode- Insulation material- Metal bottom electrode), respectively. The experimental results show that the semi-conductive composite plays an important role in the charge injection process and it presents a different tendency under different compound modes of temperature and electric field. For the low electric field (E ≤ 5 kV/mm) and the low temperature (T ≤ 50 °C), the current caused by the accumulated charges follows the rule, IS > IMS > IM. For the low electric field and high temperature (T > 50 °C), the current caused by the injected charges follows the rule, IMS > IM > IS. This phenomenon is closely related to the interface characterization and contact barrier.

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Electric characterization of films peeled from the insulation of extruded HVDC cables

Cited by 9 publications

References 6 publications

Conductivity measurement of plaque samples obtained from the insulation of high voltage extruded cables

Conductivity measurement of plaque samples obtained from the insulation of high voltage extruded cables

Synthesis of a Novel Semi-Conductive Composites Doping with La0.8Sr0.2MnO3 for Excellent Electric Performance for HVDC Cable

Charge Injection Characteristics of Semi-Conductive Composites with Carbon Black-Polymer for HVDC Cable

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