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1
Yahya, Muhammad Bin, and Muhammad Nazrolni Azmi Bin Izani. "Cable Test and Breakdown Voltage Determination of Joysense Cable Insulation." Indonesian Journal of Electrical Engineering and Computer Science 8, no. 1 (October 1, 2017): 177. http://dx.doi.org/10.11591/ijeecs.v8.i1.pp177-183.
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Cross-linked Polyethylene (XLPE) has been used as the insulation for polymeric power cables for its superior advantages. This type of cable insulation are famously known and used for their good dielectric properties, mechanical properties, thermal properties, and probability to be utilized at high temperature. This study is of four (4) parts; designing suitable method for cable test, accelerated testing procedures applied to XLPE insulation for high voltage cables, online partial discharge determination, and aging test. To study the insulation durability to AC high voltage operation, the breakdown strength and aging were investigated under different setting of temperature. The breakdown voltages of XLPE were measured at different temperatures of 30<sup>0</sup>C, 50<sup>0</sup>C and finally at 70<sup>0</sup>C. Lastly, the aging effect of cable insulation was observed by conducting the AC breakdown voltage test after the aging process. Results showed that the breakdown voltage and aging of XLPE cables will decrease with increase of temperature setting.<em> </em>
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Jörgens, Christoph, and Markus Clemens. "Electric Field and Temperature Simulations of High-Voltage Direct Current Cables Considering the Soil Environment." Energies 14, no. 16 (August 11, 2021): 4910. http://dx.doi.org/10.3390/en14164910.
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For long distance electric power transport, high-voltage direct current (HVDC) cable systems are a commonly used solution. Space charges accumulate in the HVDC cable insulations due to the applied voltage and the nonlinear electric conductivity of the insulation material. The resulting electric field depends on the material parameters of the surrounding soil environment that may differ locally and have an influence on the temperature distribution in the cable and the environment. To use the radial symmetry of the cable geometry, typical electric field simulations neglect the influence of the surrounding soil, due to different dimensions of the cable and the environment and the resulting high computational effort. Here, the environment and its effect on the resulting electric field is considered and the assumption of a possible radial symmetric temperature within the insulation is analyzed. To reduce the computation time, weakly coupled simulations are performed to compute the temperature and the electric field inside the cable insulation, neglecting insulation losses. The results of a weakly coupled simulation are compared against those of a full transient simulation, considering the insulation losses for two common cable insulations with different maximum operation temperatures. Due to the buried depth of HV cables, an approximately radial symmetric temperature distribution within the insulation is obtained for a single cable and cable pairs when, considering a metallic sheath. Furthermore, the simulations show a temperature increase of the earth–air interface above the buried cable that needs to be considered when computing the cable conductor temperature, using the IEC standards.
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Diban, Bassel, and Giovanni Mazzanti. "The Effect of Insulation Characteristics on Thermal Instability in HVDC Extruded Cables." Energies 14, no. 3 (January 21, 2021): 550. http://dx.doi.org/10.3390/en14030550.
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This paper aims at studying the effect of cable characteristics on the thermal instability of 320 kV and 500 kV Cross-Linked Polyethylene XLPE-insulated high voltage direct-current (HVDC) cables buried in soil for different values of the applied voltages, by the means of sensitivity analysis of the insulation losses to the electrical conductivity coefficients of temperature and electric field, a and b. It also finds the value of dielectric loss coefficient βd for DC cables, which allows an analytical calculation of the temperature rise as a function of insulation losses and thermal resistances. A Matlab code is used to iteratively solve Maxwell’s equations and find the electric field distribution, the insulation losses and the temperature rise inside the insulation due to insulation losses of the cable subjected to load cycles according to CIGRÉ Technical Brochure 496. Thermal stability diagrams are found to study the thermal instability and its relationship with the cable ampacity. The results show high dependency of the thermal stability on the electrical conductivity of cable insulating material, as expressed via the conductivity coefficients of temperature and electric field. The effect of insulation thickness on both the insulation losses and the thermal stability is also investigated.
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Hadi, Nabipour Afrouzi, Zulkurnain Abdul-Malek, Saeed Vahabi Mashak, and A. R. Naderipour. "Three-Dimensional Potential and Electric Field Distributions in HV Cable Insulation Containing Multiple Cavities." Advanced Materials Research 845 (December 2013): 372–77. http://dx.doi.org/10.4028/www.scientific.net/amr.845.372.
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Cross-linked polyethylene is widely used as electrical insulation because of its excellent electrical properties such as low dielectric constant, low dielectric loss and also due to its excellent chemical resistance and mechanical flexibility. Nevertheless, the most important reason for failure of high voltage equipment is due to its insulation failure. The electrical properties of an insulator are affected by the presence of cavities within the insulating material, in particular with regard to the electric field and potential distributions. In this paper, the electric field and potential distributions in high voltage cables containing single and multiple cavities are studied. Three different insulating media, namely PE, XLPE, and PVC was modeled. COMSOL software which utilises the finite element method (FEM) was used to carry out the simulation. An 11kV underground cable was modeled in 3D for better observation and analyses of the generated voltage and field distributions. The results show that the electric field is affected by the presence of cavities in the insulation. Furthermore, the field strength and uniformity are also affected by whether cavities are radially or axially aligned, as well as the type of the insulating solid. The effect of insulator type due the presence of cavities was seen most prevalent in PVC followed by PE and then XLPE.
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Li, Chao, Lin Lin, and Weidong Qu. "Study on insulation performance optimization of EMU high-voltage equipment box." Journal of Physics: Conference Series 2195, no. 1 (February 1, 2022): 012040. http://dx.doi.org/10.1088/1742-6596/2195/1/012040.
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Abstract The EMU high-voltage electrical equipment on the roof not only bears the erosion of various harsh and extreme environments, but also bears the impact of various over-voltage, and the insulation performance of the electrical equipment on the roof is seriously threatened. This paper studies the insulation optimization design method of EMU high-voltage electrical equipment, puts forward the method of adding a certain length of insulating sheath on the electrical equipment to improve the insulation performance of high-voltage equipment box, and tests the insulation optimization measures on high-voltage circuit breaker and EMU high-voltage cable. The result shows that the installation of insulating sheath is feasible to improve the insulation performance of EMU high-voltage equipment box.
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Tarko, Rafał, Jakub Gajdzica, Wiesław Nowak, and Waldemar Szpyra. "Study of the Lightning Overvoltage Protection Effectiveness of High Voltage Mixed Overhead Cable Power Lines." Energies 14, no. 8 (April 20, 2021): 2329. http://dx.doi.org/10.3390/en14082329.
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In this paper, the effectiveness of lightning overvoltage protection of cables in high voltage overhead cable lines has been analyzed. Because of the high overvoltage level, the cables are protected by surge arresters and by metallic sheath earthing. However, in practice, quite a lot of cases of electricity-evoked damage to the cable outer sheaths are observed, proving that the effectiveness of the protection used is insufficient. As a result, the cables are exposed to environmental factors, especially moisture penetration, which contributes to cable degradation. To explain the causes of this situation, simulation studies were carried out to determine the relevant factors affecting the level of expected overvoltages. The circuit-field model of the overhead cable line in EMTP-ATP, COMSOL and MATLAB software was used for determining overvoltages on the main cable insulation and the outer protective sheath. The studies reveal that the efficiency of the cable insulation overvoltage protection is ensured regardless of the lightning strike location and the crest value of its current. However, the obtained results confirm that no matter the applied protection, the cable outer sheaths may be exposed to overvoltages with higher values than those of the main insulation. Although the analysis was performed for 110 kV lines, the conclusions are general and are also applicable to power lines with higher rated voltages.
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Fu, Wenjun, Ying Xu, and Yan Gao. "A Study on Insulation Monitoring Technology of High-Voltage Cables in Underground Coal Mines Based on Decision Tree." Computational Intelligence and Neuroscience 2022 (May 23, 2022): 1–14. http://dx.doi.org/10.1155/2022/2247017.
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The insulation state of high-voltage cables in coal mines directly influences the reliability of power supply in coal mines and the level of safe production. In this paper, the degradation mechanism of cable insulation is analyzed, and an online monitoring technology of cable insulation in coal mines based on decision tree is proposed, the technical principle of the judgment method of cable degradation based on decision tree is studied, the feasibility of this technology is verified through simulation, the existing online monitoring solutions for cable insulation are analyzed, and a wide-area synchronous measurement and monitoring system for cable insulation is designed. This technology has been applied in Chinese coal mine enterprises in China and achieved a good effect.
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Nguen, Ty. "INDUCED VOLTAGES CREATED BY A HIGH-VOLTAGE CABLE." Modern Technologies and Scientific and Technological Progress 2020, no. 1 (June 16, 2020): 219–20. http://dx.doi.org/10.36629/2686-9896-2020-1-219-220.
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The results of modeling the effects of a high-voltage cable with cross-linked polyethylene insulation on adjacent power lines are presented. The calculations of the induced voltage on the adjacent voltage line were performed for five modes of operation of the 110 kV cable: symmetric and four unbalanced, caused by short circuits between the conductors, as well as between the conductors and the screen.
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Zarubin, V. S., G. N. Kuvyrkin, and I. Yu Savelyeva. "Temperature State of the Electrical Insulation Layer of a Superconducting DC Cable with Double-Sided Cooling." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 4 (97) (August 2021): 71–85. http://dx.doi.org/10.18698/1812-3368-2021-4-71-85.
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For the reliable operation of a high-voltage DC cable with high-temperature superconducting current-carrying conductors with a sufficiently high difference in electrical potentials, it is necessary to maintain a fixed temperature state not only of the conductors but also of other cable elements, including the electrical insulation layer. In this layer, despite the high electrical resistivity of its material, which can be polymer dielectrics, Joule heat is released. The purpose of this study was to build a mathematical model that describes the temperature state of an electrical insulation layer made in the form of a long hollow circular cylinder, on the surfaces of which a constant potential difference of the electric field is set. Within the study, we consider an alternative design of a cable with central and external annular channels for cooling liquid nitrogen. Using a mathematical model, we obtained integral relations that connect the parameters of the temperature state of this layer, the conditions of heat transfer on its surfaces, and the temperature-dependent coefficient of thermal conductivity and electrical resistivity of an electrical insulating material with a given difference in electrical potentials. A quantitative analysis of integral relations is carried out as applied to the layer of electrical insulation of the superconducting cable. The results of the analysis make it possible to assess the possibilities of using specific electrical insulating materials in cooled high-voltage DC cables under design, including superconducting cables cooled with liquid nitrogen
10
Jörgens, Christoph, and Markus Clemens. "Modeling the electric field at interfaces and surfaces in high-voltage cable systems." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 39, no. 5 (May 8, 2020): 1099–111. http://dx.doi.org/10.1108/compel-01-2020-0041.
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Purpose In high-voltage direct current (HVDC) cable systems, space charges accumulate because of the constant applied voltage and the nonlinear electric conductivity of the insulating material. The change in the charge distribution results in a slowly time-varying electric field. Space charges accumulate within the insulation bulk and at interfaces. With an operation time of several years of HVDC systems, typically the stationary electric field is of interest. The purpose of this study is to investigate the influence of interfaces on the stationary electric field stress and space charge density. Design/methodology/approach An analytic description of the stationary electric field inside cable insulation is developed and numerical simulations of a cable joint geometry are applied, considering spatial variations of the conductivity in the vicinity of the electrodes and interfaces. Findings With increasing conductivity values toward the electrodes, the resulting field stress decreases, whereas a decreasing conductivity results in an increasing electric field. The increased electric field may cause partial discharge, resulting in accelerated aging of the insulation material. Thus, interfaces and surfaces are characterized as critical areas for the reliability of HVDC cable systems. Research limitations/implications This study is restricted to stationary electric field and temperature distributions. The electric field variations during a polarity reversal or a time-varying temperature may result in an increased electric conductivity and electric field at interfaces and surfaces. Originality/value An analytical description of the electric field, considering surface effects, is developed. The used conductivity model is applicable for cable and cable-joint insulations, where homo- and hetero-charge effects are simulated. These simulations compare well against measurements.
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Yan, Biao, Li Zhou, Jie Chen, Feng Bo Tao, and Jian Zhang. "Testing and Diagnosis of Extra High Voltage Power Cables Using Damped AC Voltages Combined with Distributed Partial Discharge Measurement." Advanced Materials Research 1070-1072 (December 2014): 1039–43. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1039.
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State assessment method of cables with extruded insulation and their accessories, DAC withstand test combined with a diagnostic test (such as PD measurement) has two shortcomings, the output voltage is not high enough for EHV cables, it cannot detect and locate PD effectively when defects are far away from signal acquisition point. This paper focus on DAC voltages up to 250kV and a kind of distributed measurement of PD. Defects existing in arbitrary of tested cable can be accurately measured in theory by installing sensor at intervals along the tested cable. This method has been validated on a long extra high voltage cross-linked polyethylene (XLPE) insulated underground cable circuit and the filed PD test has been completed successfully.
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Andrade, Arthur F., Edson G. Costa, Filipe L. M. Andrade, Clarice S. H. Soares, and George R. S. Lira. "Design of Cable Termination for AC Breakdown Voltage Tests." Energies 12, no. 16 (August 9, 2019): 3075. http://dx.doi.org/10.3390/en12163075.
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International standards prescribe overvoltage tests to evaluate the insulating material performance of high-voltage cables. However, it is difficult to manage the electric fields at the cable ends when laboratory measurements are carried out because surface and external discharges occur at the cable termination. Therefore, this paper presents a procedure for designing cable terminations to reduce the electric field at the cable ends to appropriate levels even in the case of overvoltage tests. For this purpose, computer simulations of electric field distribution using the finite element method (FEM) were performed. A 35 kV cable model was employed as a sample. An voltage with RMS (root mean square) value of 300 kV was used as an overestimate of breakdown voltage for the internal insulating material. The cable termination model obtained through the proposed methodology allows an electric field reduction in air, preventing the occurrence of external discharges, and thus permitting the breakdown voltage measurement of the cable’s inner insulation.
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Syed Akmal Syed Jamalil, Ahmad Zaidi Abdullah, Mohd Hasrul Hamzah, and Zul Hasrizal Bohari. "Measurement and Identification of Partial Discharge in 11kV XLPE Cable Jointing." Journal of Advanced Research in Applied Sciences and Engineering Technology 31, no. 3 (August 4, 2023): 145–54. http://dx.doi.org/10.37934/araset.31.3.145154.
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The reliability of power networks can be compromised by failures in cable connections, which are often caused by poor insulation quality. The use of different insulating materials during the connection process can result in defects, leading to partial discharge (PD) in high voltage equipment. PD measurements using a Rogowski Coil sensor and a high-efficiency Oscilloscope, following the IEC-60270 guidelines, are a widely recognized method for evaluating the quality of insulation systems. Experimental measurement was performed at university high voltage laboratory. This paper focuses on measuring PDs in extension (joint) cables, where they typically occur, specifically in 11kV XLPE jointing cables, and comparing them with ordinary cables without jointing. The project aims to analyze PD signal characteristics and identify partial discharge patterns in the time and frequency domains using MATLAB. .
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Liu, Fan, Xian Tao Tao, Lin Yang, Ping Liu, and Kai Zhou. "XLPE Cable Insulation Enhancement Mechanism Based on Isopropoxide Catalyzed Siloxane." Advanced Materials Research 554-556 (July 2012): 277–81. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.277.
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In this paper, needle-shape insulation defect was made in XLPE cable samples. With high-voltage and high-frequency accelerated aging, water tree was formed inside XLPE layer. One group of the samples was injected siloxane catalyzed by isopropoxide for rejuvenation, and the breakdown voltage was significantly greater than new samples. Nano-inorganic particles were observed by scanning electron microscope (SEM) inside the breakdown channels of rejuvenated samples. The insulation enhancement mechanism is described in this paper based on the new discovery, that the insulating property of cables is enhanced by the nano-inorganic particles, because of its ability to inhibit the partial discharge damage inside the water tree channel.
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Li, Chang Ming, Guang Xiang Zhang, Chun Yang Li, and Bao Zhong Han. "Inhibition of Electrical Tree Initiation inside High-Voltage Cross-Linked Polyethylene Cable with Nonlinear Shielding Layer." Advanced Materials Research 873 (December 2013): 406–10. http://dx.doi.org/10.4028/www.scientific.net/amr.873.406.
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Electrical tree aging is one of the leading factors causing degradation and breakdown of insulation performance of high-voltage cross-linked polyethylene (XLPE) cable. A lot of attention has been paid to inhibiting electric tree initiation and propagation inside high-voltage cable. In this study, insulation composites with nonlinear electrical conductivity are prepared. Experimental results show that these composites are helpful for enhancing the apparent breakdown electric field strength of XLPE in the pole electrode system. A kind of high-voltage XLPE insulated cable with new structure is designed by using these composites as nonlinear shielding layer. Numerical simulation results indicate that nonlinear shielding layer can obviously improve the distribution of electrical field at the defect of insulation surface of high-voltage XLPE cable, and decrease the maximum electrical field strength at the defect. This new structure is potential for effectively inhibiting electrical tree initiation inside high-voltage XLPE insulation cable, thus increasing life span and operational reliability of the cable.
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Shcherba, A. A., A. D. Podoltsev, and I. M. Kucheriava. "SYSTEM FOR REMOTE MONITORING OF HIGH-VOLTAGE CABLE LINE STATE." Praci elektrodinamiki Nacionalanoi akademii nauk Ukraini Institutu 2020, no. 57 (December 2, 2020): 10–14. http://dx.doi.org/10.15407/publishing2020.57.010.
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The article proposes a device for remote monitoring of high-voltage cable line state. The device gives a possibility to measure simultaneously several diagnostic characteristics, i.e. the temperature of cable outer sheath, electric current in cable core, capacitive current to earth and uses a specially designed internal electric power source that directly converts the energy of cable electromagnetic field into electric energy with necessary parameters. By computer simulation, the temperature field distribution in the cable cores of 330 kV cable line is determined and the quantitative relationship between the directly measured temperature on the cable outer sheath and the temperature values of the cable core and insulation, which are important diagnostic characteristics of the thermal state of power cables is revealed. References 5, figures 3.
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Bezprozvannych, G. V., I. O. Kostukov, and E. S. Moskvitin. "DIFFERENTIATION OF ABSORPTION PROCESSES IN INHOMOGENEOUS INSULATION BY CURVE OF RECOVERING VOLTAGE OF POWER HIGH VOLTAGE CABLES." Tekhnichna Elektrodynamika 2021, no. 6 (October 21, 2021): 13–19. http://dx.doi.org/10.15407/techned2021.06.013.
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Based on the proposed model of spatially inhomogeneous two-layer insulation in the form of a series-parallel substitution scheme with three relaxation chains, the calculated recovery voltage curves of phase and belt paper-impregnated insulation of power cables are obtained. The model was verified by comparison with the experimental voltage curve of the power cable with paper-impregnated insulation at a voltage of 6 kV. The possibility of separation of delayed absorption processes in inhomogeneous insulation is substantiated on the basis of the analysis of high-frequency components of the spectrum of time dependences of the recovery voltage curves. The effectiveness of wavelet transform for detailing the absorption characteristics of inhomogeneous insulation of power cables is confirmed. The presence of two maxima and the dynamics of change of the ratio between them in the process of aging of inhomogeneous insulation on the reproducible curves of the regenerative voltage of power cables are established. Based on the relationship between the two amplitude values of the reproducible reduction voltage, the preferred absorption processes are determined and the appropriate criteria for assessing the state of inhomogeneous insulation of power cables are established. References 16, figure 5.
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Liang, Boyuan, Rui Lan, Qian Zang, Zhen Liu, Lin Tian, Zhaochen Wang, and Guochang Li. "Influence of Thermal Aging on Dielectric Properties of High Voltage Cable Insulation Layer." Coatings 13, no. 3 (February 27, 2023): 527. http://dx.doi.org/10.3390/coatings13030527.
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Thermal aging is one of the main reasons for the degradation of insulation properties of high voltage cable. Dielectric properties and breakdown strength are important parameters to reflect the insulation performance of the cable insulation materials. In the work, the influence of thermal aging on dielectric and breakdown performance of the cable insulation layer was studied. Firstly, XLPE cable insulation samples were prepared and the thermal aging treatment was carried out. Secondly, the microstructure and molecular structure of XLPE samples under different thermal aging time were analyzed. The dielectric properties and breakdown characteristics of XLPE samples under different thermal aging times were characterized in macro aspect. Finally, the effects of different temperatures on the molecular microstructure of XLPE were studied. The results show that with the extension of thermal aging time, the microstructure of XLPE molecule is destroyed, the macromolecular chain is gradually cleaved, and the carbonyl absorption intensity increases. At power frequency, the breakdown strength decreases from 75.37 kV/mm to 62.18 kV/mm, the relative permittivity increases from 2.44 to 2.51, and the dielectric loss increases from 1.47 × 10−4 to 3.10 × 10−3. The free volume rate of XLPE molecules increases with the increasing temperature, and the mean square displacement gradually increases. The work has good guiding significance for the safe operation and condition assessment of high-voltage cables.
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Kyrylenko, O. V., A. A. Shcherba, and I. M. Kucheriava. "INTELLECTUAL TECHNOLOGIES FOR MONITORING OF TECHNICAL STATE OF UP-TO-DATE HIGH-VOLTAGE CABLE POWER LINES." Tekhnichna Elektrodynamika 2021, no. 6 (October 21, 2021): 29–40. http://dx.doi.org/10.15407/techned2021.06.029.
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The review concerning application of fiber-optic technologies in power industry, in particular, for monitoring of modern power cables with cross-linked polyethylene insulation and integrated fiber-optic module is carried out. The new intelligent tools for control of electrical, thermal and mechanical characteristics and partial discharges in power cable lines are presented. The current operational experience for the system of Smart Cable Guard in an emergency is described. The prospects to develop and use the intellectual technologies for monitoring of technical state of up-to-date high-voltage cable power lines and their operate reliability are grounded by analysis of new diagnostic methods controlling the level of partial discharges, temperature distribution and mechanical damage in polyethylene insulation and other elements of the high- and extra-high-voltage cables with integrated fiber-optic modules. References 51, figures 8.
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Yu, Xin, Peng Fei Gao, Nai Kui Gao, Zhen Huang, and Hai Yun Jin. "Analysis on the Performance of High Insulation Materials for Current Bending XLPE Cable." Materials Science Forum 922 (May 2018): 175–79. http://dx.doi.org/10.4028/www.scientific.net/msf.922.175.
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Cross-linked polyethylene (XLPE) as insulation material has been widely used in the manufacturing of medium and high voltage cables for its excellent physical, chemical, mechanical and electrical properties. However, as cable insulation, the XLPE will degradate under service conditions, such as thermal oxidative degradation, mechanical treatment, operating environment etc. In this paper, the closed cable loop had been heated for 7 days by induced current of 1000A, and several diagnostic measurements had been adopted to characterize the performance of XLPE. Firstly FTIR has been conducted on different bending degree cable samples in order to reveal the effect of mechanical treatment on the content changes which occur in XLPE insulation layers. DSC analysis showed the effect of cooling process on the shoulder melting peak temperatures. In the last part, microstructure of the insulation of high current bending XLPE cable was studied. The results showed that the properties of the bending cable after heating by the high current changed a lot and the degree of bending also has an effect on the performance of the cable.
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Oleksyuk, I. V. "Aging of Cross-Linked Polyethylene Insulation Cable Lines." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 64, no. 2 (April 9, 2021): 121–29. http://dx.doi.org/10.21122/1029-7448-2021-64-2-121-129.
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Abstract. Preference is given to cable lines with cross-linked polyethylene insulation in electrical networks with a nominal voltage of 10 kV during reconstruction of existing and construction of new industrial enterprises. The standard service life of such cables is at least 30 years (subject to the conditions of storage, transportation, installation and operation), and the actual one is determined by the technical condition of the cable. The service life of a cable line depends on the state of its insulation, the aging of which occurs under the influence of several factors. Conventionally, all factors influencing one or another degree on the cable insulation resource can be divided into thermal, electromagnetic, climatic, mechanical and operational. The most significant reason for the insulation aging is high temperature, which accelerates the reaction of thermo-oxidative destruction, during which high-molecular polymer compounds decompose. In fact, cables are operated at temperatures below the long-term permissible values, and, therefore, the aging of the insulation is slower, and the actual service life will be longer than the standard. At present, condition of the insulation is monitored with the use of high voltage tests related to destructive testing methods. When designing and operating cable lines, it is necessary to estimate the duration of the actual service life under various operating conditions. In theory, there are several expressions for calculating the service life of a cable line when exposed to temperature, humidity, electric field and aggressive environments, but all of them are not applicable in practice due to the presence of a large number of coefficients whose values are unknown. The paper presents an analytical expression obtained for determining the service life of power electric cables, taking into account the aging of the insulation under the influence of temperature and electric field.
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Angalane, Sendil Kumar, and Elanseralathan Kasinathan. "Influence of nanofiller concentration on polypropylene nanocomposites for high voltage cables." Journal of Electrical Engineering 73, no. 3 (June 1, 2022): 174–81. http://dx.doi.org/10.2478/jee-2022-0023.
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Abstract Polymeric insulation for HVDC cable is attracting more attention in the modern power transmission system. Especially, the thermoplastic material is desirable for power cable insulation because of its recyclability and ease of processing. Thermoplastic material development is a good alternative to cross-linked polyethylene in the future. Polypropylene has the advantage of avoiding by-products during cable production, which can minimize space accumulation and degassing costs. Therefore, this study investigates the influence of nanofillers on the structural properties of isotactic polypropylene. In addition, the proposed composite material’s morphology, melting, dielectric permittivity, and breakdown strength are examined. Different weight percentages of inorganic nanofillers such as TiO2 and ZnO are used to make nanocomposite thin films. With increasing filler concentration, the dielectric constant of the nanocomposite thin film increases. Apart from that, the dielectric loss of the TiO2 nanocomposite thin film increases with weight percentage initially and it falls nearer to virgin material at a higher frequency. The breakdown strength of the nanocomposite materials shows a similar variation with filler concentration. TiO2 is more resistant to deterioration than ZnO composite. Based on the results of the complete investigation, the TiO2 nanocomposite is better suited for the insulation of HVDC cables.
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Čeović, Josip, and Matko Širola. "Medium and Low Voltage Cable Measurements - TD, PD, LIRA." Journal of Energy - Energija 65, no. 1-2 (June 27, 2022): 24–37. http://dx.doi.org/10.37798/2016651-2125.
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Elmont d.o.o. Krško – We have spread our main scope of the services from electrical maintenance, modifications implementations and quality control to cable testing area. The main reason for expanding our scope was to support Nuclear Power Plant Krško Cable Aging Management program and the world trend of LTE (Life Time Extension) in power plants. Scope of work – We are identifying potential downgraded conditions for safety and operational important cables in special areas (heat, water, radiation). Our main scope is visual control, and testing with analysis. For low voltage cables the main testing method is Line Resonance Analysis (LIRA). LIRA technology is based on the transmission line theory, through the estimation and analysis of the complex line impedance as a function of the applied signal frequency. We can monitor the global, progressive degradation of the cable insulation due to harsh environment conditions (high temperature, humidity, radiation) and detect local degradation of the insulation material due to mechanical impacts or local abnormal environmental conditions. For medium voltage cables we are using new methods with a power generator that uses Very Low Frequency – 0,1Hz (VLF). The main reason for this is that the measurement unit needs 500 times less energy than the unit which uses 50Hz frequency (50/0,1=500). With this power source we are performing dielectric loss measurements – Tan delta (TD) and Partial discharge measurements (PD). TD measurements show the severity of Water treeing in the measured cable. Water trees mainly come from moisture and are therefore present in cables that lie in manholes filled with water or they submerged in any other way. PD measurements show the severity of voids or other types of defects in cable insulation. These defects can arise during the manufacturing of the cable or they can arise during the installation of the cable or from an accident with the cable during the operational time.
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Korotkevich, M. A., and S. N. Azarov. "The Evaluation of Impact of Cable Power Lines on the Environment." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, no. 5 (October 4, 2019): 422–32. http://dx.doi.org/10.21122/1029-7448-2019-62-5-422-432.
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The thermal impact of cable power lines and structural materials of cables on the environment has been considered. A quantitative evaluation of the thermal impact of electrical cables with cross-linked polyethylene insulation on the environment was carried out using the Elcut program. Analysis of the temperature field near the loaded cable line of 10 kV demonstrated high values of soil temperature that negatively affects its redox potential and living organisms. To evaluate the environmental impact of electrical cable materials, an approach has been developed that takes into account not only the toxicity of the materials but also their volumetric content in the cable. Cable lines with cables with traditional paper-oil insulation cause more damage to the environment than cable lines with cables, insulated with crosslinked polyethylene. The environment, in turn, also has an impact on the electrical cables: the values of long-term permissible load currents depend on the ambient temperature (when laying cables in the open air, in an earthen trench or in cable rooms). The impact of solar radiation on the thermal conditions of the electric cable is estimated. A comparative analysis of the complex environmental impact of electric cables with traditional insulation and insulation of crosslinked polyethylene demonstrated that unarmored cable with crosslinked polyethylene insulation at a voltage of 10 kV (regardless of the type of its shell) causes less damage to the environment than the same traditional cable throughout the considered temperature range on their surfaces.
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Ul-Hamid, Anwar, Khaled Y. Soufi, Luai M. Al-Hadhrami, and Ahsan M. Shemsi. "Failure investigation of an underground low voltage XLPE insulated cable." Anti-Corrosion Methods and Materials 62, no. 5 (September 7, 2015): 281–87. http://dx.doi.org/10.1108/acmm-02-2014-1352.
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Purpose – This paper aims to determine the effect of exposure of underground electrical cables to chemically contaminated water. Design/methodology/approach – Visual inspection and photography were carried out to record the appearance of electrical cables. Failed and un-failed cable samples were collected and analyzed using light microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Sand and water samples were chemically tested for contaminants. Findings – Underground low-voltage 0.6/1-kV cross-linked polyethene insulated cables belonging to a chemical production plant suffered failure after four years of service. Excavation of the cable trench revealed that the cables were buried in sand polluted with chemically contaminated water. The cables were discolored and covered with corrosion deposits. Experimental results indicated that the cable insulation was heavily degraded and the outer jacket of polyvinyl chloride exhibited cracks that had penetrated through its thickness. Water and sand surrounding the cable were found to have high concentrations of ammonia. Mechanical testing of the cables indicated high values of stiffness that could contribute to the formation of cracks at the surface. Practical implications – It was concluded that contamination in the water had degraded the cable, resulting in the development of a network of branched cracks within the cable insulation through which water could permeate, leading to eventual failure of the cable. Accelerated degradation took place due to exposure to the contaminated environment, which promoted aging and brittleness. Continued exposure of electric cables to contamination would lead to power failures and plant shutdowns. Originality/value – This paper provides an account of a failure investigation of low-voltage electrical cable buried underground. It discusses the role of contaminated environment in the eventual failure of electrical cable due to corrosion. This information will be useful for plant engineers and project managers working in any industry that makes use of chemicals.
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Nguyen, Dung. "THE INFLUENCE OF POLYPROPYLENE LAMINATED PAPER ON THE BREAKDOWN STRENGTH OF INSULATION FOR HIGH TEMPERATURE SUPERCONDUCTING CABLE." Vietnam Journal of Science and Technology 58, no. 1 (February 21, 2020): 46. http://dx.doi.org/10.15625/2525-2518/58/1/14387.
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Polypropylene Laminated Paper (PPLP) and Kraft paper has been used as ac power insulation for conventional cable as well as high temperature superconducting (HTS) cable because of its prominent insulating characteristics. However, research on the use of PPLP/Kraft insulation for HTS cables are thinly scattered. In this paper, the effect of PPLP on the breakdown strength of PPLP/Kraft multi-layer sample impregnated with liquid nitrogen (LN2) under ac and impulse applied voltage was studied. In addition, the breakdown strength characteristics of PPLP and Kraft samples were also investigated in order to determine breakdown strength characteristics of PPLP/Kraft insulation directly. It was found from the experimental data that the breakdown strength increases as the component ratio of PPLP in the PPLP/Kraft sample increases and is slightly affected by the inserting position of PPLP but in impulse case, the breakdown strength strongly depends on the number of PPLP and the relative position of PPLP.
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Zhang, Zhen-Peng, Chang-Ji Zheng, Mei Zheng, Hong Zhao, Jian-Kang Zhao, Wei-Feng Sun, and Jun-Qi Chen. "Interface Damages of Electrical Insulation in Factory Joints of High Voltage Submarine Cables." Energies 13, no. 15 (July 30, 2020): 3892. http://dx.doi.org/10.3390/en13153892.
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As a key accessory of high-voltage (HV) insulated submarine cable, the factory joints of the cross-linked polyethylene (XLPE) represent an unpredictable uncertainty in cable-connecting fabrications by means of the extruded molding joint (EMJ) technique. The electrical breakdown pathways formed at the interfaces between recovery insulation and cable body under alternative current 500 kV voltages are specifically investigated by microstructure characterizations in combination with the electric field and fractal simulations. Dielectric-defected cracks in tens of micrometers in insulation interfaces are identified as the strings of voids, which dominate insulation damages. The abnormal arrangements of XLPE lamellae from scanning electron microscopy (SEM) imply that the structural micro-cracks will be formed under interface stresses. Electrical-tree inception is expedited to a faster propagation due to the poor dielectric property of interface region, manifesting as 30% lower of tree inception voltage. The longer free-paths for accelerating charge carriers in the cracks of interface region will stimulate partial discharging from needle electrodes. The carbonized discharging micro-channels arising in interface region illustrate that the partial discharging will be triggered by the electrical-trees growing preferentially along the defect cracks and could finally develop into insulation damages. The mechanism of forming cracks in the fusion processes between the molten XLPE of cable body and the molten cross-linkable PE of recovery insulation is elucidated, according to which the crack-caused degradation of insulation performance is expected to be alleviated.
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Li, Chang Ming, Bao Zhong Han, Long Zhao, and Chun Peng Yin. "Inhibiting Effect of Nonlinear Shielding Layer on Electrical Tree Propagation inside Insulation Layer of High-Voltage Cable." Advanced Materials Research 989-994 (July 2014): 1273–77. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.1273.
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Nonlinear insulated materials can uniform electric field distribution in non-uniform electric field. In order to inhibit the electric tree initiation and propagation inside high-voltage cross-linked polyethylene (XLPE) insulated cable, a kind of 220kV high-voltage XLPE insulated cable with new structure is designed by embedding nonlinear shielding layer into XLPE insulation layer of high-voltage cable with traditional structure in this study. Experimental and simulation results indicate that the nonlinear shielding layer can effectively inhibit electrical tree propagation inside the XLPE specimens, and obviously extend the breakdown time caused by electric tree propagation. When the electrical tree propagates into the nonlinear shielding layer sandwiched between insulation layers of cable, the electric field distribution near the tip of electrical tree is obviously improved. These findings prove the feasibility and the effectivity of inhibiting electrical tree propagation inside high-voltage cable by adding nonlinear shielding layer into the insulation layer.
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Codjo, Egnonnumi Lorraine, Bashir Bakhshideh Zad, Jean-François Toubeau, Bruno François, and François Vallée. "Machine Learning-Based Classification of Electrical Low Voltage Cable Degradation." Energies 14, no. 10 (May 15, 2021): 2852. http://dx.doi.org/10.3390/en14102852.
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Low voltage distribution networks have not been traditionally designed to accommodate the large-scale integration of decentralized photovoltaic (PV) generations. The bidirectional power flows in existing networks resulting from the load demand and PV generation changes as well as the influence of ambient temperature led to voltage variations and increased the leakage current through the cable insulation. In this paper, a machine learning-based framework is implemented for the identification of cable degradation by using data from deployed smart meter (SM) measurements. Nodal voltage variations are supposed to be related to cable conditions (reduction of cable insulation thickness due to insulation wear) and to client net demand changes. Various machine learning techniques are applied for classification of nodal voltages according to the cable insulation conditions. Once trained according to the comprehensive generated datasets, the implemented techniques can classify new network operating points into a healthy or degraded cable condition with high accuracy in their predictions. The simulation results reveal that logistic regression and decision tree algorithms lead to a better prediction (with a 97.9% and 99.9% accuracy, respectively) result than the k-nearest neighbors (which reach only 76.7%). The proposed framework offers promising perspectives for the early identification of LV cable conditions by using SM measurements.
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Zaytsev, Evgeny, and Vladimir Lebedev. "Development of the Thermal Equivalent Circuit for Evaluating the Capacity of High Voltage Cables in Real Time." Applied Mechanics and Materials 698 (December 2014): 586–91. http://dx.doi.org/10.4028/www.scientific.net/amm.698.586.
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The authors of this paper justify the construction of the thermal equivalent circuit for a three-phase high voltage cable line that describes the transient thermal processes in the cross section of the line. According to the authors, the proposed scheme, if taken as a basis, allows to solve the task of evaluating the power capacity of high-voltage cable lines in real-time and predict heating of cables with the aim to prevent thermal degradation of the insulation.
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Lee, Jae-In, Woo-Hee Jeong, Minh-Chau Dinh, In-Keun Yu, and Minwon Park. "Comparative Analysis of XLPE and Thermoplastic Insulation-Based HVDC Power Cables." Energies 16, no. 1 (December 23, 2022): 167. http://dx.doi.org/10.3390/en16010167.
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The application of cross-linked polyethylene (XLPE) cables to voltage sourced converter (VSC)-based high voltage direct current (HVDC) systems has already been technically verified and has become common, and thermoplastic (TP) is attracting attention as an insulation material for next-generation cables due to the recent development of material-related technologies. However, studies related to TP cables are mainly focused on improving material properties, and studies related to cable systems are insufficient. In this paper, XLPE and TP cables were designed for application to VSC-based HVDC systems, and major characteristics such as electric field distribution and thermal stability were compared and analyzed through overvoltage simulation. The insulation design method of HVDC cable was presented, and the design was performed using XLPE and TP insulation materials. The temperature and electric field profiles of the cables were also analyzed through a finite element method simulation. To analyze the performance of the designed cable, it was simulated with the PSCAD/EMTDC program. Based on the simulation results, the major characteristics of XLPE and TP cables were compared and analyzed. Results showed that in the case of TP cables, insulation properties were excellent, but thermal conductivity was relatively low; therefore, countermeasures are needed.
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Cheng, Yujia, Guang Yu, and Zhuohua Duan. "Breakdown Properties of Cables with Different Inorganic, Insulating Nanomaterials." Inorganics 9, no. 12 (December 20, 2021): 90. http://dx.doi.org/10.3390/inorganics9120090.
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The insulation performance of cable insulating materials can be optimised via matrix modification. Typically, low-density polyethylene (LDPE) is used as the matrix, and a certain proportion of nanoparticles are added to this matrix. To explore the effects of nanoparticles with different forms on the structural interface and crystal morphology of the material, nano-MMT and nano-ZnO were added to LDPE, and comparative experiments were carried out. Based on microscopic test results, material insulation performance changes before and after optimisation were observed. Then, simulation cable models with different insulating materials were developed. Based on the simulated electrical measurements, the thermal breakdown performance of the different insulating materials was tested. According to infrared stereo vision detection results, anomalous temperature points in the cables can be located accurately. Finally, based on macroscopic test results, we verified whether the inorganic, insulating nanomaterials meet the requirements for high-voltage transmission.
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Wang, Lei, Zhe Wang, Lin Niu, Lijuan Guo, Ying Pei, Hongbo Li, Zhiguang Ma, Zhenhai Zhang, and Lina Chen. "High Voltage Cable Fault Location Technology Based on Traveling Wave." Journal of Physics: Conference Series 2468, no. 1 (April 1, 2023): 012167. http://dx.doi.org/10.1088/1742-6596/2468/1/012167.
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Abstract High voltage cable line is an important part of power grid; its stable operation is of great significance to urban power system. This paper proposed a high voltage cable insulation monitoring system using traveling wave. The travelling wave data are collected by high precision satellite timing signal and an on-line fault location system for high voltage cable is designed.
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Oh, Dong-Hun, Ho-Seung Kim, and Bang-Wook Lee. "A Novel Diagnosis Method for Void Defects in HVDC Mass-Impregnated PPLP Cable Based on Partial Discharge Measurement." Energies 14, no. 8 (April 7, 2021): 2052. http://dx.doi.org/10.3390/en14082052.
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Mass Impregnated PPLP cable, which is applied to various high-voltage direct current (HVDC) projects due to its excellent dielectric and temperature properties, has a problem wherein voids are formed inside the butt-gap due to cavitation. However, there has been no previous research into technology for void defect identification and insulation diagnosis on HVDC MI-PPLP cables. In this paper, to propose an insulation diagnosis method for void defects in HVDC MI-PPLP cable, the direct current (DC) void discharge patterns were analyzed according to the specimen temperature and the magnitude of applied voltage using the pulse sequence analysis method. In addition, to confirm the pre-symptoms of dielectric breakdown in MI-PPLP cable due to DC void discharge, partial discharge patterns were analyzed continuously until dielectric breakdown occurred. From the experimental results, DC void discharge patterns of the same shape were obtained regardless of the specimen temperature and the magnitude of applied voltage. In addition, it was confirmed that new insulation aging patterns were generated as electrical and thermal aging occurred due to the continuous DC void discharge. Therefore, it is demonstrated that identification and insulation diagnosis of void defects in HVDC MI-PPLP cable is possible through the obtained DC void discharge and insulation aging patterns.
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Fard, Mehrtash, Mohamed Farrag, Scott McMeekin, and Alistair Reid. "Electrical Treeing in Cable Insulation under Different HVDC Operational Conditions." Energies 11, no. 9 (September 12, 2018): 2406. http://dx.doi.org/10.3390/en11092406.
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Electrical treeing (ET) can irreversibly deteriorate the insulation of polymeric power cables leading to a complete failure. This paper presents the results of an experimental investigation into the effects of unipolar and polarity reversing DC voltages on electrical tree (ET) and partial discharge (PD) behavior within high voltage direct current (HVDC) cross linked polyethylene (XLPE) cable insulation. A double needle configuration was adopted to produce non-uniform electric fields within the insulation samples, potentially leading to electrical trees. The development of trees was monitored through an optical method and the associated partial discharge signals were measured through an electrical detection technique, simultaneously. The analysis of the results shows reasonable relation between the formation of ETs and the type of the applied voltages. The polarity reversing attribute of the test voltages has a pronounced effect on formation and growth of electrical trees. This implicates an interaction between the space charges that accumulate within polymeric materials and the operational polarity reversing electric fields, which causes insulation degradation. Therefore, study of influencing HVDC operational parameters on insulation degradations can contribute to improvements in cable design and advancement in insulation diagnostic strategies applicable in HVDC systems leading to more effective asset management.
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Xu, Guangke, Xing Li, Weiwei Zhang, Yuxin Yun, Lingying Chen, Jiahua Shen, Guoming Wang, and Gyung-Suk Kil. "Application and verification of partial discharge measurement system for power cable based on oscillating wave voltage." Journal of Electrical Engineering 71, no. 5 (September 1, 2020): 333–39. http://dx.doi.org/10.2478/jee-2020-0045.
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Abstract Compared with conventional methods for insulation performance evaluation of power cables, the oscillating wave test system used in partial discharge measurement for power cables has advantages of high integrity, easy operation, low power consumption, and compact size in addition, partial discharge, defect localization, and dielectric loss can be measured simultaneously without any damage to cable insulation. Therefore, the oscillating wave test system has been widely applied for insulation performance evaluation of newly installed as well as fault power cables. However, there is no study so far on the verification method of oscillating wave test system. This paper dealt with the application and verification for cable partial discharge measurement devices based on oscillating wave voltage, which is aimed to verify performances of oscillating wave voltage generator, partial discharge measurement, and partial discharge localization. The proposed verification system is expected to be applied in the admittance testing and regular verification of oscillating wave test system, for the purpose of improving the its accuracy and standardization in partial discharge measurement of power cable.
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Rybarz, Jacek, Sebastian Borucki, Michał Kunicki, Aneta Kucińska-Landwójtowicz, and Dawid Wajnert. "Influence of the Cable Accessories Installing Method on the Partial Discharge Activity in Medium Voltage Cables." Energies 15, no. 12 (June 8, 2022): 4216. http://dx.doi.org/10.3390/en15124216.
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This article proposes a method to modify the construction of a medium voltage (MV) heat shrinkable cable termination in cases of atypical damage to the shields of cross-linked polyethylene (XLPE) insulated cables. The proposed solutions include a modified method of assembling electric field control coating. An attempt was made to check the effect of such damage to the shields of MV cables with XLPE insulation on the level of occurrence of partial discharges within the cable termination. The investigations included testing the XRUHAKXS 1 × 240/25 cable type using the electric method (ME) and high frequency (HF) method with sinusoidal AC test voltage. As a result of the measurements, the values of total charges in the period and phase-resolved partial discharge (PRPD) patterns were obtained. The presented experimental results show the influence of the damage of the semiconducting coating surface on the occurrence of a defect in the cable termination without a modified method of control mantissa pinning. We suggest new methods of assembling MV cable accessories in the case of the presented coating damage in MV cable insulation.
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Englund, V., R. Huuva, S. M. Gubanski, and T. Hjertberg. "High efficiency voltage stabilizers for XLPE cable insulation." Polymer Degradation and Stability 94, no. 5 (May 2009): 823–33. http://dx.doi.org/10.1016/j.polymdegradstab.2009.01.020.
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Andritsch, Thomas, Alun Vaughan, and Gary C. Stevens. "Novel insulation materials for high voltage cable systems." IEEE Electrical Insulation Magazine 33, no. 4 (July 2017): 27–33. http://dx.doi.org/10.1109/mei.2017.7956630.
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Kumara, Sarath, Xiangdong Xu, Thomas Hammarström, Yingwei Ouyang, Amir Masoud Pourrahimi, Christian Müller, and Yuriy V. Serdyuk. "Electrical Characterization of a New Crosslinked Copolymer Blend for DC Cable Insulation." Energies 13, no. 6 (March 19, 2020): 1434. http://dx.doi.org/10.3390/en13061434.
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To design reliable high voltage cables, clean materials with superior insulating properties capable of operating at high electric field levels at elevated temperatures are required. This study aims at the electrical characterization of a byproduct-free crosslinked copolymer blend, which is seen as a promising alternative to conventional peroxide crosslinked polyethylene currently used for high voltage direct current cable insulation. The characterization entails direct current (DC) conductivity, dielectric response and surface potential decay measurements at different temperatures and electric field levels. In order to quantify the insulating performance of the new material, the electrical properties of the copolymer blend are compared with those of two reference materials; i.e., low-density polyethylene (LDPE) and peroxide crosslinked polyethylene (XLPE). It is found that, for electric fields of 10–50 kV/mm and temperatures varying from 30 °C to 70 °C, the DC conductivity of the copolymer blend is in the range of 10−17–10−13 S/m, which is close to the conductivity of crosslinked polyethylene. Furthermore, the loss tangent of the copolymer blend is about three to four times lower than that of crosslinked polyethylene and its magnitude is on the level of 0.01 at 50 °C and 0.12 at 70 °C (measured at 0.1 mHz and 6.66 kV/mm). The apparent conductivity and trap density distributions deduced from surface potential decay measurements also confirmed that the new material has electrical properties at least as good as currently used insulation materials based on XLPE (not byproduct-free). Thus, the proposed byproduct-free crosslinked copolymer blend has a high potential as a prospective insulation medium for extruded high voltage DC cables.
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Cheetham, Peter, Jose Viquez, WooJin Kim, Lukas Graber, Chul H. Kim, and Sastry V. Pamidi. "High-Temperature Superconducting Cable Design Based on Individual Insulated Conductors." Advances in Materials Science and Engineering 2018 (November 1, 2018): 1–10. http://dx.doi.org/10.1155/2018/3637873.
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The idea of insulating individual high-temperature superconducting (HTS) tapes was explored as a dielectric design to reduce the risk and complexity of HTS cable manufacturing. Applying insulation on individual HTS tapes is amenable to continuous manufacturing processes and opens up material choices for the insulation. In this study, heat shrink insulation was selected as the material choice for exploring the possibility of this design philosophy because of its commercial availability in multiple thicknesses. A systematic set of selection criteria was developed for the selection of appropriate heat shrink for given HTS tape dimensions. The cryogenic dielectric characteristics of insulated HTS tapes were evaluated both in liquid nitrogen and gaseous helium environments at 77 K. Dielectric characteristics of tapes with a single layer of thicker insulation were compared with those insulated using multiple layers of thinner insulation to evaluate the relative merits of each method. Several model power cables were fabricated using the PET insulated tapes, and their dielectric behavior was evaluated at 77 K in gaseous helium environment. The results suggest that the explored method is useful for HTS power cables operating at low voltages (<1,000 V) primarily due to the limitation on achieving thick insulation with high quality using heat shrink tubing. The suitable processes of insulating longer lengths of samples with additional dielectric benefits are discussed.
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Azizian Fard, Mehrtash, Mohamed Emad Farrag, Alistair Reid, and Faris Al-Naemi. "Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages." Energies 12, no. 16 (August 14, 2019): 3113. http://dx.doi.org/10.3390/en12163113.
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Insulation degradation is an irreversible phenomenon that can potentially lead to failure of power cable systems. This paper describes the results of an experimental investigation into the influence of direct current (DC) superimposed with harmonic voltages on both partial discharge (PD) activity and electrical tree (ET) phenomena within polymeric insulations. The test samples were prepared from a high voltage direct current (HVDC) cross linked polyethylene (XLPE) power cable. A double electrode arrangement was employed to produce divergent electric fields within the test samples that could possibly result in formation of electrical trees. The developed ETs were observed via an optical method and, at the same time, the emanating PD pulses were measured using conventional techniques. The results show a tenable relation between ETs, PD activities, and the level of harmonic voltages. An increase in harmonic levels has a marked effect on development of electrical trees as the firing angle increases, which also leads to higher activity of partial discharges. This study of the influencing operational parameters of HVDC converters on power cable insulation is predicted to contribute to enhancements in cable design and progressive advancement in condition monitoring and insulation diagnostic techniques that can lead to more effective asset management in HVDC systems.
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Yurov, A. A., D. E. Storozhenko, A. V. Lukonin, and D. N. Kuimov. "The device for monitoring the insulation breakdown zone of power cable lines in distribution networks with isolated neutral system during high-voltage diagnostic." E3S Web of Conferences 411 (2023): 01049. http://dx.doi.org/10.1051/e3sconf/202341101049.
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The article considers an electrical device designed for diagnostic work in distribution networks of 6-10 kV, namely, the determination of damage zones in case of failure of insulating materials of cable lines during high-voltage diagnostics with a rectified voltage of negative polarity. The novelty of the developed device is its ability to connect directly to a high-voltage cable line without additional matching devices. The device is capable of detecting damage zones in lines up to 10 km remotely with an error of up to 0.2% of the cable length. The prefix allows you to fix any variants of damage to single-phase and three-phase cable lines with high transient resistance at the site of damage without the operation of “burning” insulation, which significantly reduces the time of repair work at the controlled facility.
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Wang, Yu Li, Jian Kang Zhao, and Rong Xia. "Research on Characteristics of Partial Discharge in Typical Defects of High-Voltage XLPE Cable." Advanced Materials Research 986-987 (July 2014): 459–64. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.459.
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Six models of typical insulation defects are designed and lab-simulated system used for partial discharge (PD) detection of cables and accessories has been constructed to study PD characteristics of internal insulation defects in 110 kV XLPE cable system. By employing CPDM, a kind of on-line PD detector, test data of various models including related PD diagrams are obtained for our research. Based on these characteristic parameters, discharge characteristic analyses of a single PD pulse are presented and statistical operators can be obtained by numerical calculation. The experimental results show that CPDM on-line detecting method is effective for detecting PD signals from internal defects of cable accessories. In addition, there are significant differences in the some statistical parameters (e.g. discharge phase, discharge repetition rate, etc) and characteristic parameters of time-domain PD waveform which can be used as reference points for PD patterns identification in future research.
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Zaytsev, Evgeny. "Development of Calculation Methodology of Thermal Equivalent Circuit’s Parameters for Predicting Temperature of High Voltage Cable Lines 110 - 500 kV." Applied Mechanics and Materials 792 (September 2015): 272–79. http://dx.doi.org/10.4028/www.scientific.net/amm.792.272.
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This paper is concerned with the development of techniques to the calculation of the thermal equivalent circuit parameters for the high-voltage cable line laid in the ground. The topology of the scheme was developed in author’s previous publication. This article discusses the parameters of the circuit which simulate the environment of the cable line. Calculation techniques of these parameters are described for cables laid in a plane and a trefoil pattern. The proposed scheme allows one to predict heating of cables on the day ahead in order to prevent thermal degradation of the insulation.
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Yu, Ting, Sanwei Liu, Xiaoli Duan, Cheng Zhong, Jianjia Duan, Zeyu Zeng, and Daoyuan Zhang. "Research on Defects of High Voltage Cable Fusion Joint Using XLPE Insulation Material." Journal of Physics: Conference Series 2378, no. 1 (December 1, 2022): 012017. http://dx.doi.org/10.1088/1742-6596/2378/1/012017.
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Abstract High-voltage cable fusion joints are made on site. Affected by environmental conditions, fusion joints are prone to small defects that are not easy to find, resulting in frequent accidents after the joints are put into operation. There is currently no effective method to detect small defects inside the joint. Therefore, this paper proposes to use digital radiography nondestructive test technology to detect the main insulation and conductor recovery process of high-voltage cable fusion joints. The results show that the digital radiography nondestructive test method can effectively find defects such as microporous bubbles, conductor bending, and eccentricity in the main insulation of XLPE fusion joints. The on-site anatomy demonstrates the accuracy of the test results, and the digital radiography nondestructive test can effectively detect the defects of high-voltage cable fusion joints. Experiments have verified that the decrease of cross-linked pipe temperature and nitrogen pressure can lead to the generation of microporous bubbles in the XLPE main insulation. For conductor bending and eccentricity defects, the limit value of the welding conductor bending gap is 11mm through simulation calculation.
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Zhou, Yifan, Wei Wang, and Tailong Guo. "Space Charge Accumulation Characteristics in HVDC Cable under Temperature Gradient." Energies 13, no. 21 (October 24, 2020): 5571. http://dx.doi.org/10.3390/en13215571.
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One of the main issues that affect the development of high-voltage direct-current (HVDC) cable insulation is the accumulation of space charge. The load operation of an HVDC cable leads to the formation of a radially distributed temperature gradient (TG) across the insulation. In this study, the space charge accumulation in a cross-linked polyethylene (XLPE) cable is measured under a DC electric field and TG using the pulsed electro-acoustic (PEA) method, and the effect of the TG on the space charge behavior is investigated. In addition, the bipolar charge transport (BCT) model and the conductivity model based on an improved cylindrical geometry are used to simulate the charge behavior in the HVDC XLPE cable under TG, and the experimental and simulated results are compared. The results show that the higher temperature of the cable conductor promotes the accumulation of homocharge near the side of high temperature. Additionally, with the increase of the TG, not only does more heterocharge accumulates adjacent to the side of low temperature, but more space charge also extends into the bulk of the cable insulation. More attention should be paid to the conductor shield layer and the insulation shield layer in HVDC cables. Moreover, the BCT model can more accurately describe the experimental results than the conductivity model.
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Jörgens, Christoph, and Markus Clemens. "Thermal breakdown in high voltage direct current cable insulations due to space charges." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 37, no. 5 (September 3, 2018): 1689–97. http://dx.doi.org/10.1108/compel-12-2017-0531.
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Purpose In high voltage direct current (HVDC), power cables heat is generated inside the conductor and the insulation during operation. A higher amount of the generated heat in comparison to the dissipated one, results in a possible thermal breakdown. The accumulation of space charges inside the insulation results in an electric field that contributes to the geometric electric field, which comes from the applied voltage. The total electric field decreases in the vicinity of the conductor, while it increases near the sheath, causing a possible change of the breakdown voltage. Design/methodology/approach Here, the thermal breakdown is studied, also incorporating the presence of space charges. For a developed electro-thermal HVDC cable model, at different temperatures, the breakdown voltage is computed through numerical simulations. Findings The simulation results show a dependence of the breakdown voltage on the temperature at the location of the sheath. The results also show only limited influence of the space charges on the breakdown voltage. Research limitations/implications The study is restricted to one-dimensional problems, using radial symmetry of the cable, and does not include any aging or long-term effect of space charges. Such aging effect can locally increase the electric field, resulting in a reduced breakdown voltage. Originality/value A comparison of the breakdown voltage with and without space charges is novel. The chosen approach allows for the first time to assess the influence of space charges and field inversion on the thermal breakdown.
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Zhu, Zhao, Han, Wang, Wang, Liu, Xie, and Zhu. "Thermal Effect of Different Laying Modes on Cross-Linked Polyethylene (XLPE) Insulation and a New Estimation on Cable Ampacity." Energies 12, no. 15 (August 3, 2019): 2994. http://dx.doi.org/10.3390/en12152994.
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This paper verifies the fluctuation on thermal parameters and ampacity of the high-voltage cross-linked polyethylene (XLPE) cables with different insulation conditions and describes the results of a thermal aging experiment on the XLPE insulation with different operating years in different laying modes guided by Comsol Multiphysics modeling software. The thermal parameters of the cables applied on the models are detected by thermal parameter detection control platform and differential scanning calorimetry (DSC) measurement to assure the effectivity of the simulation. Several diagnostic measurements including Fourier infrared spectroscopy (FTIR), DSC, X-ray diffraction (XRD), and breakdown field strength were conducted on the treated and untreated specimens in order to reveal the changes of properties and the relationship between the thermal effect and the cable ampacity. Moreover, a new estimation on cable ampacity from the perspective on XLPE insulation itself has been proposed in this paper, which is also a possible way to judge the insulation condition of the cable with specific aging degree in specific laying mode for a period of time.
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Yu, Seunggun, Seong Hwan Lee, Jin Ah Han, Myung Sang Ahn, Hoyyul Park, Se Won Han, and Dae Ho Lee. "Insulative ethylene-propylene copolymer-nanostructured polypropylene for high-voltage cable insulation applications." Polymer 202 (August 2020): 122674. http://dx.doi.org/10.1016/j.polymer.2020.122674.
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