Water Trees in Cross-Linked Polyethylene Power Cables

Water tree characteristics have been investigated for low-density polyethylene by applying powerfrequency ac voltages with high-frequency components, which are simulated output voltages of a pulse-width-mod.ulation inverter. If we compare the water-tree length among single-frequency voltages, the water tree grows faster if the frequency is higher. However, if we superpose a powerfrequency voltage onto the high-frequency voltage, the tx-ee growth is suppressed. The tree length becomes short.er if the superposed power-frequency voltage is higher.This surprising result is explainable by considering that the zero-crossing of the applied voltage plays an important role for the tree propagation. In case that the high-frequency voltage is superposed onto a dc voltage, the dc voltage seems not to have any influence to the tree growth. This result can be also explained by considering the number of voltage reversals at the tree tip.

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“…The tree length becomes shorter with an increase in the 50 Hz component. A similar tendency is seen among the volt,ages (4), (8), (9) and (10).…”

Section: Methodssupporting

confidence: 79%

“…The numerals nest to the data points show that the applied voltages were voltages (4) to (10). Furthermore, (A), (B), (C), (D), and (E) are the data obtained by applying the voltage (5) for 170,340,460, 700, and 850 hours, respectively.…”

Section: Methodsmentioning

confidence: 99%

Role of voltage zero-crossing in propagation of water trees

Mukai

Suzuki²,

Ohki³

et al.

IEEE 1997 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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“…Treeing patterns observed in Ethylene-Propylene Rubber insulated cables employed herein are similar in appearance to those previously observed in PE and XLPE. 4. Tree initiation and propagation in EPDM apparently follows a mechanism similar to that which occurs in PE or XLPE.…”

Section: Electro-chemical Treeing In Translucent Systemsmentioning

confidence: 91%

Electro-Chemical Treeing in Ethylene-Propylene Rubber Compounds

Bernstein¹,

Srinivas²,

Hogan³

et al. 1975

Journal of Elastomers & Plastics

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~ ~ ~ ~ ~~ABSTRACT: A series of Ethylene-Propylene Diene (EPDM) compounds, designed to be transparent or translucent in nature, were formulated for the purpose of studying electro-chemical treeing, Systems were tested in sheet form for evaluation of physical properties and crosslinking behavior, and extruded under laboratory conditions over 14 AWG bare copper wire into thin wall mini-cables. Cables were then subjected to the Phelps Dodge Accelerated Treeing Test. All EPDM systems exhibited electro-chemical tree formation to some extent; trees originated at the site of contaminants and at the conductor. Treeing patterns observed are of similar appearance to those formed in Polyethylene and Crosslinked Polyethylene insulation.The nature of the EPDM systems, preparation techniques, physical properties and treeing effects are discussed. Results indicated that electrochemical treeing is a phenomenon characteristic of both rubbery and semicrystalline polymeric materials.

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“…Water trees in insulations lead to significant deterioration of the electrical properties and to local increase of the electric field [247]. A reduction of resistivity was observed in various studies by Bahder et al [248], Tabata et al [249], Tanaka et al [250], Steennis et al [236], Wojtas [251] and so forth. As the water concentration increases in the “tree regions”, the permittivity increases correspondingly compared to the material without water trees [252].…”

Section: Water Treeing In Nanocompositesmentioning

confidence: 99%

Polyethylene Nanocomposites for Power Cable Insulations

et al. 2018

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This review represents a comprehensive study of nanocomposites for power cables insulations based on thermoplastic polymers such as polyethylene congeners like LDPE, HDPE and XLPE, which is complemented by original results. Particular focus lies on the structure-property relationships of nanocomposites and the materials’ design with the corresponding electrical properties. The critical factors, which contribute to the degradation or improvement of the electrical performance of such cable insulations, are discussed in detail; in particular, properties such as electrical conductivity, relative permittivity, dielectric losses, partial discharges, space charge, electrical and water tree resistance behavior and electric breakdown of such nanocomposites based on thermoplastic polymers are described and referred to the composites’ structures. This review is motivated by the fact that the development of polymer nanocomposites for power cables insulation is based on understanding more closely the aging mechanisms and the behavior of nanocomposites under operating stresses.

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Water Trees in Cross-Linked Polyethylene Power Cables

Cited by 36 publications

References 2 publications

Role of voltage zero-crossing in propagation of water trees

Role of voltage zero-crossing in propagation of water trees

Electro-Chemical Treeing in Ethylene-Propylene Rubber Compounds

Polyethylene Nanocomposites for Power Cable Insulations

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