Enhanced charge injection in rough HVDC extruded cable interfaces

Doedens, Espen; Jarvid, E. Markus; Flindt, Christian; Gubanski, Stanislaw

doi:10.1109/tdei.2019.008213

Cited by 10 publications

(13 citation statements)

References 8 publications

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“…For pure LDPE as shown in the Figure 4 a, there is no obvious space charge accumulation under 20 kV/mm, but a small amount of heterocharge could be observed near the cathode under 40 kV/mm. It is considered that this heterocharge comes from ionization of impurities or transport of injected charges [ 18 , 22 , 23 ]. For composites, there is also no obvious space charge accumulation under 20 kV/mm in the composites except for XLPE-PS 1# and XLPE-PS 2# as shown in Figure 4 c,f, where a negative charge accumulates near the cathode as homocharge and could be noticed almost across the whole samples.…”

Section: Resultsmentioning

confidence: 99%

Crosslinking Dependence of Direct Current Breakdown Performance for XLPE-PS Composites at Different Temperatures

Cao

Zhong

et al. 2021

Polymers

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In this paper, crosslinked polyethylene-polystyrene (XLPE-PS) composites with different degrees of crosslinking were fabricated by using different crosslinking agent contents and their direct current (DC) breakdown performance at 30~90 °C was investigated. Results show that with the increase of the degree of crosslinking, the crystallinity of XLPE-PS composites decreases gradually, but their DC breakdown strength demonstrates an increasing trend at 30~90 °C and the enhancement also increases with the rise of temperature. And as the degree of crosslinking increases, the elastic modulus of XLPE-PS composites is reduced and the loss tangent peak temperature decreases but the peak shifts to a lower value, which reveals the suppression of the relaxation process for crystallites. It is believed that high DC breakdown strength with good temperature stability for XLPE-PS composites with a larger degree of crosslinking is attributable to the presence of PS and suppression in the formation of crystallites due to crosslinking.

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Section: Resultsmentioning

confidence: 99%

Crosslinking Dependence of Direct Current Breakdown Performance for XLPE-PS Composites at Different Temperatures

Cao

Zhong

et al. 2021

Polymers

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“…Sample preparation, storage and space charge measurements performed in the present study ((A), left). Previously performed work ((B), right) encompassing profilometry, field simulation and injection current estimation [5][6][7], allowing for the derivation of modified injection laws in the present study. A Cartesian coordinate system (x, y, z) is adopted, with estimated current density oriented here in the x-direction.…”

Section: Length = Cable Circumferencementioning

confidence: 99%

“…The surface structure was measured through profilometry and implemented in COMSOL Multiphysics ® , as indicated in Figure 2 [8]. Thereby, different distributions of the field enhancement factors (FEF) were found through solving Laplace's equation on measured surface profiles [7], which were dependent on surface geometry (referred to as Laplacian field below). Such effects establish a geometric field distribution, as shown in Figure 3B, where, locally, the field enhancements intensify charge injection from their respective regions on the surface [3,4].…”

Section: Length = Cable Circumferencementioning

confidence: 99%

“…Roughness is known to influence the local field distribution at the interface, locally enhancing or reducing the electric field due to the introduced micro-scale geometrical inhomogeneities [3,4]. In earlier work [5][6][7], such field distributions were assessed and their impact on Schottky and Fowler-Nordheim types of charge injection was evaluated. Figure 2 further exemplifies the work performed in the past and present studies.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 2 further exemplifies the work performed in the past and present studies. [5][6][7], allowing for the derivation of modified injection laws in the present study. A Cartesian coordinate system (x, y, z) is adopted, with estimated current density oriented here in the x-direction.…”

Section: Introductionmentioning

confidence: 99%

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Space Charge Accumulation at Material Interfaces in HVDC Cable Insulation Part I—Experimental Study and Charge Injection Hypothesis

et al. 2020

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On-site installation of accessories on extruded polymeric high voltage cables in a common practice. The procedure requires the shaping of the physical interface between the cable insulation surface and the pre-molded accessory body. On such interfaces, rough surfaces should be avoided in order to limit space charge accumulation in the insulation, which affects the cable performance by reducing insulation life-time, creating conditions for local field enhancement, and, respectively, the formation of possible breakdown path e.g. by electrical treeing. Space charge measurements on cable insulation peelings were undertaken to assess the space charge injection and accumulation on interfaces with varying degrees of surface roughness in order to improve understanding on this subject. The results of the measurements confirm the hypothesis regarding the enhancement of charge injection from rough surfaces when electric field strength exceeds a certain level. The accumulated charge density in the material is shown to strongly depend on the field strength and temperature in both polarization and subsequent depolarization measurements. These results emphasize that a bipolar charge transport model that incorporates field and temperature dependencies of charge injection, trapping, detrapping, and recombination processes needs to be adopted to accurately describe the observed electric conduction phenomena.

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Interfacial microstructure and insulation properties of 500 kV EHVDC XLPE cable factory joint under different roughness and degassing durations

Meng

Chen

Dai

et al. 2021

Polymer Degradation and Stability

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Enhanced charge injection in rough HVDC extruded cable interfaces

Cited by 10 publications

References 8 publications

Crosslinking Dependence of Direct Current Breakdown Performance for XLPE-PS Composites at Different Temperatures

Crosslinking Dependence of Direct Current Breakdown Performance for XLPE-PS Composites at Different Temperatures

Space Charge Accumulation at Material Interfaces in HVDC Cable Insulation Part I—Experimental Study and Charge Injection Hypothesis

Interfacial microstructure and insulation properties of 500 kV EHVDC XLPE cable factory joint under different roughness and degassing durations

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