Analysis of Water Trees and Characterization Techniques in Xlpe Cables

Priya, S.; Anjum, A. Mubashira

doi:10.17485/ijst/2014/v7sp7.29

Cited by 10 publications

(3 citation statements)

References 8 publications

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“…The presence of free moisture in the power cable leading to the formation of tree structures,water treeing ( Fig. 1) [1][2][3][4][5][6][7], which are generated in the amorphous phase of the polyethylene, i.e. on the boundaries of the grains-crystallites (Fig.…”

mentioning

confidence: 99%

Relaxations Losses in Polyethylene Insulation of Coaxial Cable Structure During Aging in High Humidity Conditions

Bezprozvannych¹,

Kyessayev²

2016

Elektroteh. elektromeh.

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Introduction. The presence of free moisture in power cables leading to the formation of tree structures-water treeing, which originate in the amorphous phase polyethylene and are a major cause of degradation of the polymer insulation. They represent the damage of the polymer size from several microns to 1 mm, developing technology for insulation defects under the combined action of the electric field and the moisture diffusing from the environment. Water treeing destroys the polymer chain, resulting in the formation of microcavities filled with moisture. The dynamics of water treeing and subtle properties largely depend on the composition, morphology of the polymer insulation, chemical nature of the defect, in which they originate. Due to the force of gravity in the water formed typical only for her region with locally ordered structure-clusters, which cause loss of relaxation. Purpose. Features presence of relaxation losses in high-frequency range in polyethylene insulation during aging in high humidity conditions of samples power and RF cables. Methodology. Samples of the power cable for the voltage of 35 kV with a crosslinked polyethylene insulation radial water-blocking protection from moisture and radio-frequency coaxial cable with thermoplastic insulation for 1440 hours in a humidity of 100%. The dielectric loss tangent measured resonance method before and after aging. Originality. Experimentally found evidence of the existence in the polymer cable insulation free water in the form of areas with locally ordered structure-clusters. It is found that the solid polyethylene insulation in the frequency dependence of dielectric loss tangent maximum relaxation shown one at 10 MHz in the initial state, and there are two additional frequency range 500 kHz-5 MHz after moistening. For cross-linked polyethylene insulation characteristic of large width Δf of the frequency spectrum in which the observed relaxation losses. It is obvious that the width of each of the relaxation maxima is associated with characteristic fractal cluster size. It is important that the hydrated solid and foamed polyethylene insulation to show individuality, typical only for water clusters which are detected by high-frequency dipole relaxation peaks dielectric loss tangent. There is a positive correlation between the bandwidth Δf of relaxation maxima and the rate of decrease of insulation resistance by applying a high DC voltage. Practical value. Establishing a correlation between the bandwidth of relaxation maxima and the rate of decrease in the insulation resistance test objects in the laboratory makes it possible to diagnose the presence of free moisture in the power and RF cables by measuring the insulation resistance in exploitation. References 10, figures 7.

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mentioning

confidence: 99%

Relaxations Losses in Polyethylene Insulation of Coaxial Cable Structure During Aging in High Humidity Conditions

Bezprozvannych¹,

Kyessayev²

2016

Elektroteh. elektromeh.

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“…Since there were many values obtained from the result of simulation, the study only focused in the interested area as demonstrated in the table 4.1-table 4.4. 4, it can be seen that when increased the value of voltage source and frequency in the circuit, the magnitude of current in the faulty cable was smaller than the value of the magnitude of current in healthy cable. Therefore, it could be said that the occurrence of water trees would lead to the reduction of magnitude of current in relation to the rising of voltage and frequency.…”

Section: The Leakage Current Under Frequency and Voltage Variationmentioning

confidence: 94%

“…Molecules of polyethylene are not chemically bonded as shown in figure 2.2 (B) can be easily deformed at over melting temperature, while XLPE molecules bonded in a three dimensional network as shown in figure 2.2 (C) and figure 2.2 (D), making strong resistance to deform even at high temperature. Crystallinity refers to the degree of structural order in a solid figure 2.2 (E) [4]. In a crystal, the atoms or molecules are arranged in a regular, periodic manner.…”

Section: Xlpe Insulated Power Cablementioning

confidence: 99%

Xlpe Insulated High Voltage Underground Cable Assessment by Leakage Current Studies

Konglysan

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The leakage current characteristic of high voltage underground cable was studied in this research. It is quite useful to assess the status of insulation after using for a while. This is an important data to do a decision making to prolong its lifetime or replacement a new one. A study was taken with the simulation circuit established from each none breakdown failure in XLPE insulated high voltage underground cable such as water treeing, electrical treeing, partial discharge, aging according to usage and surface leakage current along the cable’s accessories, etc. This study was performed with Proteus 8.0 on single phase cable with variation of voltage and frequency. The results of leakage current from each case were compared with a healthy cable in order to establish a specific tendency characteristic. These characteristics were used to be a tool to classify the failure type in the insulation. Moreover, an analytical tool was developed with Excel@ in order to evaluate the status of an insulation with failure type (if any) from the change behavior of leakage current and phase angle. This was done by comparison the leakage currents obtained from each cable in a three-phase cable system with has a same construction and length. The simulation of leakage current data from a three-phase cable system integrated with any failure type in any phase in random was putted in to the developing tool. The obtained result could be determined correctly both in the failure phase and failure type.

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Water trees in polyethylene insulated power cables: Approach to water trees initiation mechanism

El-Zein

Mohamed

Talaat

2020

Electric Power Systems Research

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Analysis of Water Trees and Characterization Techniques in Xlpe Cables

Cited by 10 publications

References 8 publications

Relaxations Losses in Polyethylene Insulation of Coaxial Cable Structure During Aging in High Humidity Conditions

Relaxations Losses in Polyethylene Insulation of Coaxial Cable Structure During Aging in High Humidity Conditions

Xlpe Insulated High Voltage Underground Cable Assessment by Leakage Current Studies

Water trees in polyethylene insulated power cables: Approach to water trees initiation mechanism

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