22 results on '"Zhijin Zhang"'
Search Results
2. A New Reconstruction Algorithm for Geometric Shape of Static Overhead Transmission Lines
- Author
-
Zhijin Zhang, Ran Li, Xingliang Jiang, Tian Liang, Xinhan Qiao, and Guohui Pang
- Subjects
Energy Engineering and Power Technology ,Electrical and Electronic Engineering - Published
- 2022
3. AC Breakdown Characteristics of Polluted 10-kV Post Insulator With Concentric Externally Gapped Line Arrester
- Author
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Sundrarajan Raji, Zhijin Zhang, Xingliang Jiang, Xinhan Qiao, Jianping Hu, and Zhen Fang
- Subjects
Materials science ,Electric field ,Arc flash ,Empirical formula ,Energy Engineering and Power Technology ,Insulator (electricity) ,Electric potential ,Electrical and Electronic Engineering ,Composite material ,Lightning arrester ,Intensity (heat transfer) ,Voltage - Abstract
This paper studies the AC pollution breakdown characteristics of the EGLA and broaden current knowledge of pollution flashover. Compared with the flashover of the normal insulator, three kinds of specificity of the EGLA were found. Firstly, the pollution flashover process can be divided into three categories. Secondly, the wet flashover voltage, Uf _wet, of the novel insulator is higher than the dry flashover voltage, Uf _dry. Thirdly, the piecewise fitting methods with aESDD^-b+d and aESDD^-b+ cESDD^-d are more suitable for fitting the empirical formula of flashover voltage. Furthermore, to explain specificity, the electric potential and electric field distribution are calculated based on the finite element method. Calculated results indicate that when the EGLA is covered with a 0.5mm water film, the maximum electric field intensity decreased from 2.17 kV/cm to 1.99 kV/cm. Also, U_arrester (the withstand voltage of the insulation section) was obtained from the tests and it presents a discontinuous and random increasing trend until flashover occurs, which is considered to be one of the important reasons for the specificity. Besides, based on the Obenaus model and Hampton's criterion, we further analyzed the arc development process by a simplified plate model
- Published
- 2022
4. Study on DC pollution flashover performance of various types of long string insulators under low atmospheric pressure conditions
- Author
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Zhijin Zhang, Xinliang Jiang, Yafeng Chao, Lling Chen, and Caixin Sun
- Subjects
Electric insulators -- Environmental aspects ,Electric insulators -- Research ,Business ,Computers ,Electronics ,Electronics and electrical industries - Published
- 2010
5. Equivalence of influence of pollution stimulating methods on DC flashover stress of ice-covered insulators
- Author
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Xingliang Jiang, Ling Chen, Zhijin Zhang, Caixin Sun, and Jianlin Hu
- Subjects
Electric insulators -- Research ,Electric insulators -- Testing ,Business ,Computers ,Electronics ,Electronics and electrical industries - Published
- 2010
6. Study of ac pollution flashover performance of porcelain insulators at high altitude sites of 2800 ~ 4500 m
- Author
-
Xingliang, Jiang, Zhijin, Zhang, Jihe, Yuan, Qin, Hu, and Liyun, Luo
- Subjects
Electric insulators -- Design and construction ,Electric insulators -- Materials ,Electric power transmission -- Research ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
The external insulation of electric equipments will be affected by the atmospheric conditions in the high altitude regions. However, a few investigations at the high altitude sites of 3000 m and above have been conducted. This paper reports on the laboratory tests of artificially polluted cap-and-pin porcelain insulators performed at the high altitudes of 2800 m to 4500 m. The test results and analysis show that the pollution flashover voltages in high altitude regions are affected not only by the pollution grades but also by the atmospheric parameters. The exponent characterizing the influence of equivalent salt deposit density is 0.26 to 0.29 and the one characterizing the influence of nonsoluble deposit density is 0.09 to 0.15. The ac pollution flashover voltage UF will decrease with the decrease of air pressure P and increase with the decrease of ambient temperature t. [U.sub.f] is a power function of the ration of air pressure P/[P.sub.o] and also is a power function of the ambient temperature coefficient (1 + 0.02(t - 20)). The average exponent characterizing the influence of air pressure is about 0.56 and the exponent characterizing the influence of ambient temperature is about 0.21 for the three types of insulators in the paper. Index Terms--AC insulator, atmospheric parameter, flashover, high altitude site, pollution grade.
- Published
- 2009
7. Study on the DC Flashover Performance of Various Types of Insulators With Fan-Shaped Nonuniform Pollution
- Author
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Jinwei You, Jianlin Hu, Dongdong Zhang, Xingliang Jiang, Jiayao Zhao, and Zhijin Zhang
- Subjects
Pollution ,Materials science ,business.industry ,media_common.quotation_subject ,Extrapolation ,Electrical engineering ,Energy Engineering and Power Technology ,Insulator (electricity) ,Mechanics ,Arcing horns ,Electric power transmission ,Flashover voltage ,Arc flash ,Electrical and Electronic Engineering ,business ,Leakage (electronics) ,media_common - Abstract
In areas with heavy dust or continuous wind in a single direction, fan-shaped nonuniform contamination at the windward and leeward side of the insulator string may affect flashover performance. In this paper, dc pollution flashover tests of insulators under fan-shaped nonuniform pollution were presented, and a comparison of flashover performance among 7-unit suspension insulator strings with four different disk profiles was made. Then, the influence of fan-shaped nonuniform pollution on flashover voltage, arc propagation, and critical leakage distance were investigated. Research results indicate that the insulators with different types were influenced variously on their flashover stress, utilization rate of creepage distance, and critical leakage distance by fan-shaped nonuniform pollution. A reduction in the ratio W/L of windward to leeward side salt deposit density (SDD) from 1/1 to 1/15 gave a median 35% $\pm$ 4% decrease in flashover strength. The extrapolation of results for the seven-unit strings suggests that some increment in shed space or structure height of the insulator can be preferable in dc transmission lines where there is fan-shaped nonuniform pollution accumulating at the windward and leeward side of the insulator string.
- Published
- 2015
8. Predictive Model for Equivalent Ice Thickness Load on Overhead Transmission Lines Based on Measured Insulator String Deviations
- Author
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Ze Xiang, Xingliang Jiang, Qin Hu, Jianlin Hu, Zhijin Zhang, and Lichun Shu
- Subjects
Engineering ,business.industry ,Energy Engineering and Power Technology ,Tangent ,Insulator (electricity) ,Mechanics ,Physics::Geophysics ,Ice thickness ,Electric power system ,Electric power transmission ,Safe operation ,Electronic engineering ,Astrophysics::Earth and Planetary Astrophysics ,Electrical and Electronic Engineering ,business ,Electrical conductor ,Physics::Atmospheric and Oceanic Physics ,Icing - Abstract
Transmission-line icing presents a serious threat to the safe operation of power systems. Therefore, the icing condition of overhead transmission lines must be accurately calculated for online monitoring and prewarning systems. Based on the icing data obtained at Xuefeng Mountain Natural Icing Stations (XMNIS), the cross-sectional shape of glaze icing on conductors was studied, and the correction coefficient of the actual nonuniform ice was proposed to provide an accurate and convenient method for field icing measurement. In addition, by analyzing the characteristics of the tension and tilt of the insulator string at the iced tangent tower, a new mechanical calculation model considering the ice and wind loads was established. One-month field observations and experiments were conducted in XMNIS, and it is shown that the calculation results have good agreement with experiment results, which suggests that the model can be used for ice thickness calculation and online monitoring on transmission lines.
- Published
- 2014
9. Study on the Wetting Process and Its Influencing Factors of Pollution Deposited on Different Insulators Based on Leakage Current
- Author
-
Caixin Sun, Haizhou Huang, David Wenzhong Gao, Jianlin Hu, Xingliang Jiang, and Zhijin Zhang
- Subjects
Pollution ,media_common.quotation_subject ,Environmental engineering ,Energy Engineering and Power Technology ,Insulator (electricity) ,Pollution flashover ,Arc flash ,Environmental science ,Insulator contamination ,Wetting ,Electrical and Electronic Engineering ,Control methods ,Voltage ,media_common - Abstract
Pollution-induced flashover has a serious threat on the safe and reliable operation of power systems. It is known that the pollution flashover voltage is directly related to the wetting degree of the pollution layer. But the wetting performance characteristics and control method of pollution layer on insulators have not been properly specified in the existing pollution test standards. In this paper, the wetting processes of the pollution layer on different types of insulators have been studied in an artificial fog chamber. In our test studies, the leakage current on the surface of polluted insulators under a different test environment is measured and then the curves of leakage current varying with time are plotted. Furthermore, the main influencing factors of the wetting process of the pollution layer have been analyzed in this paper. Test results show that the wetting process of the pollution layer can be characterized well through the change of leakage current, and when the leakage current reaches the maximum value, the pollution layer is saturated with fog. Specifically, during the wetting process, the leakage current gradually increases until the maximum value and then decreases; the time for the pollution layer to become saturated is dependent on the salt-deposited density (SDD), the steam fog input rate, the temperature in the artificial fog chamber, and the type of insulators. It is found that with the increase of SDD and the decrease of the steam fog input rate and the temperature in the climate chamber, the necessary wetting time will increase, and the more complex the insulator structure is, the longer the wetting time will be.
- Published
- 2013
10. Study on DC Pollution Flashover Performance of Various Types of Long String Insulators Under Low Atmospheric Pressure Conditions
- Author
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Yafeng Chao, Caixin Sun, Jianlin Hu, Xinliang Jiang, Ling Chen, and Zhijin Zhang
- Subjects
Pollution ,Engineering ,Atmospheric pressure ,business.industry ,media_common.quotation_subject ,Electrical engineering ,Energy Engineering and Power Technology ,Insulator (electricity) ,Mechanics ,law.invention ,Low-pressure area ,law ,Electrical network ,Arc flash ,Electric discharge ,Electrical and Electronic Engineering ,business ,media_common ,Voltage - Abstract
In this paper, the dc pollution flashover performance of various types of porcelain, glass, and composite insulators is investigated. It also presents analysis of the dc flashover process of polluted insulator string at high altitude using insight from high-speed photography. The research results indicate that the relationship between the dc pollution flashover voltage and the string length of insulators is basically linear, the characteristic exponents describing the influence degree of air pressure on pollution flashover voltage vary between 0.35 and 0.77 and are related to the insulator types and pollution degree, etc., the characteristic exponents describing the influence degree of pollution on flashover voltage vary between 0.24 and 0.36 and are related to the insulator types and air pressure, etc. Based on the flashover phenomena using the insight from high-speed photography, a new physical model explaining the flashover mechanism for a polluted insulator string at high altitude is introduced, which can be expressed as an electrical circuit consisting of a surface arc of length x1 and air-gap arc of length x2 in series with a resistance representing the wet pollution layer. In addition, the exponent n describing the influence degree of air pressure on flashover voltage for the polluted insulator is discussed.
- Published
- 2010
11. Simulation and Experimental Investigation of DC Ice-Melting Process on an Iced Conductor
- Author
-
Zhijin Zhang, Xingliang Jiang, Caixin Sun, Lichun Shu, and Songhai Fan
- Subjects
Meteorology ,Energy Engineering and Power Technology ,Storm ,Atmospheric model ,Wind speed ,Conductor ,law.invention ,Electric power transmission ,law ,Electrical network ,Electrical and Electronic Engineering ,Air gap (plumbing) ,Electrical conductor ,Geology ,Marine engineering - Abstract
Ice melting with dc is one of the key technologies to prevent the Chinese power grid from ice storms. Especially after the severe ice storm in the southern part of China in early 2008, dc ice-melting technology has drawn more attention than ever before. However, there are few satisfactory methods to select correct parameters so the ice-melting project rarely achieves desired effects in some cases when applied in Hunan, Guizhou, and other provinces in China. Therefore, it is of great significance to develop a method to estimate parameters which is applicable in the practical situation for dc ice melting. To handle this, the factors, such as wind velocity, ambient temperature, current density and ice-layer thickness were analyzed and then a dc ice-melting model is put forward in this paper. Both the results of simulations and experiments show that the ice-melting process can be divided into three stages composed of temperature rising, ice melting, and ice shedding, among which the ice melting is the key stage consuming most of the ice-melting time. In this stage, an elliptic airgap is formed and widened gradually with an influence on the ice-melting time and the temperature of the conductor. The experiments in the artificial climate chamber demonstrate that the results of the presented model are consistent with those of the experiments generally, so it can be employed to estimate the parameters of ice melting in practical engineering as reference.
- Published
- 2010
12. Study of AC Pollution Flashover Performance of Porcelain Insulators at High Altitude Sites of 2800 $\sim$ 4500 m
- Author
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Jihe Yuan, Qin Hu, Liyun Luo, Zhijin Zhang, and Xingliang Jiang
- Subjects
Pollution ,Atmospheric pressure ,media_common.quotation_subject ,Air pollution ,Environmental engineering ,Energy Engineering and Power Technology ,Effects of high altitude on humans ,Atmospheric sciences ,medicine.disease_cause ,Arc flash ,medicine ,Environmental science ,Electric discharge ,Electrical and Electronic Engineering ,Power function ,Temperature coefficient ,media_common - Abstract
The external insulation of electric equipments will be affected by the atmospheric conditions in the high altitude regions. However, a few investigations at the high altitude sites of 3000 m and above have been conducted. This paper reports on the laboratory tests of artificially polluted cap-and-pin porcelain insulators performed at the high altitudes of 2800 m to 4500 m. The test results and analysis show that the pollution flashover voltages in high altitude regions are affected not only by the pollution grades but also by the atmospheric parameters. The exponent characterizing the influence of equivalent salt deposit density is 0.26 to 0.29 and the one characterizing the influence of nonsoluble deposit density is 0.09 to 0.15. The ac pollution flashover voltage U f will decrease with the decrease of air pressure P and increase with the decrease of ambient temperature t . U f is a power function of the ration of air pressure P/P 0 and also is a power function of the ambient temperature coefficient (1 + 0.02(t - 20)). The average exponent characterizing the influence of air pressure is about 0.56 and the exponent characterizing the influence of ambient temperature is about 0.21 for the three types of insulators in the paper.
- Published
- 2009
13. Comparison of DC Pollution Flashover Performances of Various Types of Porcelain, Glass, and Composite Insulators
- Author
-
Lichun Shu, Feng Mao, Zhijin Zhang, Jihe Yuan, Xingliang Jiang, and Jianlin Hu
- Subjects
Materials science ,Composite number ,Arc flash ,Forensic engineering ,Energy Engineering and Power Technology ,Electric discharge ,Insulator (electricity) ,Dielectric ,Electrical and Electronic Engineering ,Composite material ,Composite insulators ,Voltage ,Leakage (electronics) - Abstract
Based on the artificial pollution tests, the flashover performance of various types of DC porcelain and glass suspension insulators as well as composite long-rod insulators were analyzed and compared. The test results show that there is a nearly linear relation between the pollution flashover voltage and the disc-type insulator string length. The flashover voltage gradients of the insulators are affected by their materials and shed shapes. The antipollution performances of glass insulators are superior to those of porcelain insulators with the same profile. The flashover voltage gradients of composite insulators are higher than those of porcelain or glass ones. The exponent characterizing the influence of salt deposit density on the pollution flashover voltage is dependent on the profile and the material of insulators, and the values of the composite insulators' exponents are smaller than those of porcelain or glass insulators, namely, the influence of the pollution on the composite insulators is relatively less. The effectiveness of leakage distances of porcelain or glass insulators is less than 0.9 while that of composite insulators is higher than 0.9.
- Published
- 2008
14. Study on AC Artificial-Contaminated Flashover Performance of Various Types of Insulators
- Author
-
Caixin Sun, Zhijin Zhang, Jihe Yuan, Xingliang Jiang, and Jianlin Hu
- Subjects
Engineering ,business.industry ,Electrical engineering ,Energy Engineering and Power Technology ,Insulator (electricity) ,Dielectric ,Contamination ,Flashover voltage ,Polymer insulators ,Arc flash ,Electric discharge ,Electrical and Electronic Engineering ,Composite material ,business ,Salt deposit density - Abstract
Artificial pollution tests have been carried out to study AC flashover performances of various types of porcelain, glass, and polymeric insulators in this paper. The experimental results show that the polluted flashover voltage Uf is affected by equivalent salt deposit density rhoESDD and nonsoluble deposit density rhoNSDD, the influences of which are independent of each other. Based on the analyses of the flashover voltages, the correction formulas of the flashover voltages Uf of various insulators at various rhoESDD and rhoNSDD levels are pointed out. The experimental results also show that there is a distinct difference among the flashover voltages of various types of polluted insulators. At the same pollution degree, the antipollution performance of the fog-type glass insulator is better than those of the outer-rib porcelain insulators. In terms of the effectiveness of creepage distance of insulators, the antipollution performance of polymeric insulators is superior to those of porcelain and glass insulators.
- Published
- 2007
15. Positive Switching Impulse Discharge Performance and Voltage Correction of 1-m Rod-Plane Air Gap
- Author
-
Caixin Sun, Shaohua Wang, Zhijin Zhang, Jun Wang, Lichun Shu, Xingliang Jiang, and Jianlin Hu
- Subjects
Physics ,Atmospheric pressure ,business.industry ,Electrical engineering ,Energy Engineering and Power Technology ,Humidity ,High voltage ,Impulse (physics) ,Computational physics ,Density of air ,Electrical and Electronic Engineering ,business ,Air gap (plumbing) ,Power function ,Voltage - Abstract
Switching impulse discharge performance of air gaps at high altitudes, which is a fundamental in the extremely high voltage external insulation design, remains an unsolved key technology across the world. Due to the limited applicable range of "g" parameter method recommended by IEC Publication 60-1(1989), this paper aims to explore the relationship between positive switching impulse 50% discharge voltage U 50 of rod-plane air gaps and atmospheric parameters, and proposes two new voltage correction methods based on the parameter "g" and the atmospheric pressure ratio, respectively. The two methods have been proved by the experimental investigations carried out on 1-m rod-plane air gap both in the artificial climate chamber and at three spots of different high altitudes in this study. The results show that, if the additional influence of absolute humidity is considered, the positive switching impulse 50% discharge voltage U50 of rod-plane air gaps is a power function of relative pressure and relative air density; the "g" parameter method in IEC Publication 60-1(1989) is not applicable to the regions with an altitude above 2000 m or the condition of h/delta>15 g/m3; compared with the correction method based on the "g" parameter method, the correction method based on relative atmospheric pressure has a wider applicable range and less error; when the absolute humidity increases 1 g/m3 , U50 varies within the range of 1.0%-1.15%
- Published
- 2007
16. Study on AC Flashover Performance and Discharge Process of Polluted and Iced IEC Standard Suspension Insulator String
- Author
-
Xingliang Jiang, Yan Wang, Shaohua Wang, Zhijin Zhang, and Shujiao Xie
- Subjects
Engineering ,business.industry ,Electrical engineering ,Energy Engineering and Power Technology ,Insulator (electricity) ,Dielectric ,Conductivity ,Physics::Geophysics ,Icicle ,Arc flash ,Electric discharge ,Astrophysics::Earth and Planetary Astrophysics ,Electrical and Electronic Engineering ,Composite material ,business ,Air gap (plumbing) ,Physics::Atmospheric and Oceanic Physics ,Icing - Abstract
Based on the results of experimental investigations performed on the polluted and iced IEC standard suspension insulator strings of 3~21 units, the ac flashover performance and discharge process are discussed in this paper. It is put forward that the icing stress product (ISP), defined as the product of the ice-layer conductivity and the ice layer weight per centimeter of dry arc distance can be taken as a characteristic parameter to indicate the effect of ice accretions and contaminants on the flashover voltage. The flashover stress of an ice-covered insulator string can be expressed as a power function of ISP and has a linear relationship with the length of the insulator string. The partial arc of an iced insulator string is initiated by the breakdown of the air gaps between the tips of icicles and iced insulator surface and the persistence is much longer than that of a polluted insulator string
- Published
- 2007
17. Simulation and Experimental Investigation of DC Ice-Melting Process on an Iced Conductor.
- Author
-
Xingliang Jiang, Songhai Fan, Zhijin Zhang, Caixin Sun, and Lichun Shu
- Subjects
ICE storms ,POWER resources ,ELECTRIC power systems ,ELECTRICAL conductors ,ELECTRICAL engineering - Abstract
Ice melting with dc is one of the key technologies to prevent the Chinese power grid from ice storms. Especially after the severe ice storm in the southern part of China in early 2008, dc ice-melting technology has drawn more attention than ever before. However, there are few satisfactory methods to select correct parameters so the ice-melting project rarely achieves desired effects in some cases when applied in Hunan, Guizhou, and other provinces in China. Therefore, it is of great significance to develop a method to estimate parameters which is applicable in the practical situation for dc ice melting. To handle this, the factors, such as wind velocity, ambient temperature, current density and ice-layer thickness were analyzed and then a dc ice-melting model is put forward in this paper. Both the results of simulations and experiments show that the ice-melting process can be divided into three stages composed of temperature rising, ice melting, and ice shedding, among which the ice melting is the key stage consuming most of the ice-melting time. In this stage, an elliptic airgap is formed and widened gradually with an influence on the ice-melting time and the temperature of the conductor. The experiments in the artificial climate chamber demonstrate that the results of the presented model are consistent with those of the experiments generally, so it can be employed to estimate the parameters of ice melting in practical engineering as reference. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
18. Study of AC Pollution Flashover Performance of Porcelain Insulators at High Altitude Sites of 2800 ∼ 4500m.
- Author
-
Xingliang Jiang, Zhijin Zhang, Jihe Yuan, Qin Hu, and Liyun Luo
- Subjects
- *
ALTERNATING currents , *ELECTRIC insulators & insulation , *ATMOSPHERIC pressure , *PORCELAIN , *HIGH voltages , *TEMPERATURE , *POLLUTION - Abstract
The external insulation of electric equipments will be affected by the atmospheric conditions in the high altitude regions. However, a few investigations at the high altitude sites of 3000 m and above have been conducted. This paper reports on the laboratory tests of artificially polluted cap-and-pin porcelain insulators performed at the high altitudes of 2800 m to 4500 m. The test results and analysis show that the pollution flashover voltages in high altitude regions are affected not only by the pollution grades but also by the atmospheric parameters. The exponent characterizing the influence of equivalent salt deposit density is 0.26 to 0.29 and the one characterizing the influence of nonsoluble deposit density is 0.09 to 0.15. The ac pollution flashover voltage Uf will decrease with the decrease of air pressure P and increase with the decrease of ambient temperature t. Uf is a power function of the ration of air pressure P/Po and also is a power function of the ambient temperature coefficient (1 + 0.02(t - 20)). The average exponent characterizing the influence of air pressure is about 0.56 and the exponent characterizing the influence of ambient temperature is about 0.21 for the three types of insulators in the paper. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
19. Positive Switching Impulse Discharge Performance and Voltage Correction of Rod-Plane Air Gap Based on Tests at High-Altitude Sites.
- Author
-
Xingliang Jiang, Lichun Shu, Jianlin Hu, Zhijin Zhang, Shaohua Wang, and Jihe Yuan
- Subjects
RAILROAD electrification ,ELECTRIC discharges ,ELECTRIC testing ,ELECTRIC potential ,VOLTAGE regulators ,ALTITUDES ,HUMIDITY ,MATHEMATICAL optimization - Abstract
Abstract-The Qinghai-Tibet Railway is the highest railway in the world. Up to now, there were no test and service data for the external insulation of the power-supply project of the railway system above 4000 m above sea level (a.s.l.). The "g" parameter method recommended by IEC Publication 60.1 (1989) has a limited applicable range. Therefore, based on the former tests carried on the artificial climate chamber (ACC), in this paper, a series of test investigations is conducted on the positive switching impulse (PSI) discharge performance of rod-plane air gaps with gap spacing of 0.25 to 3.0 m at the six high-altitude sites along the Qinghai-Tibet Railway with altitudes of 2820 to 5050 m. With analyses of the mathematical optimization method on the test results, the new correction method of discharge voltage is proposed. They are also checked and compared with the test results obtained from the simulation tests carried out in the ACC. It is indicated that the 50% PSI discharge voltage U[sub50] of the air gap at high altitude is a power function of gap spacing d, also a power function of relative pressure of dry air and absolute humidity. The influence law of atmospheric parameters on U[sub50] obtained at high-altitude sites is the same as that obtained in the ACC. U[sub50]. obtained in the ACC, is about 8.15% higher than that obtained at high-altitude sites due to the influence of nonsimulated factors, such as ultraviolet ray and cosmic radiation. The "g" parameter method is not applicable to the regions with an altitude above 2800 m. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
20. Comparison of DC Pollution Flashover Performances of Various Types of Porcelain, Glass, and Composite Insulators.
- Author
-
Xingliang Jiang, Jihe Yuan, Lichun Shu, Zhijin Zhang, Jianlin Hu, and Feng Mao
- Subjects
ELECTRIC insulators & insulation ,PORCELAIN ,ELECTRIC potential ,POLLUTION prevention ,INSULATING materials ,DIRECT currents ,DIRECT current power transmission ,INDUSTRIAL contamination - Abstract
Based on the artificial pollution tests, the fiashover performance of various types of dc porcelain and glass suspension insulators as well as composite long-rod insulators were analyzed and compared. The test results show that there is a nearly linear relation between the pollution fiashover voltage and the disc-type insulator string length. The flashover voltage gradients of the insulators are affected by their materials and shed shapes. The antipollution performances of glass insulators are superior to those of porcelain insulators with the same profile. The fiashover voltage gradients of composite insulators are higher than those of porcelain or glass ones. The exponent characterizing the influence of salt deposit density on the pollution flashover voltage is dependent on the profile and the material of insulators, and the values of the composite insulators' exponents are smaller than those of porcelain or glass insulators, namely, the influence of the pollution on the composite insulators is relatively less. The effectiveness of leakage distances of porcelain or glass insulators is less than 0.9 while that of composite insulators is higher than 0.9. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
21. Study on AC Artificial-Contaminated Flashover Performance of Various Types of Insulators.
- Author
-
Xingliang Jiang, Jihe Yuan, Zhijin Zhang, Jianlin Hu, and Caixin Sun
- Subjects
ALTERNATING current circuits ,ALTERNATING currents ,ELECTRONIC circuit design ,ELECTRIC currents ,LIGHTNING ,ELECTRIC oscillators ,ELECTRIC circuits ,ELECTRIC relays ,SHORT circuits - Abstract
Artificial pollution tests have been carried out to study ac flashover performances of various types of porcelain, glass, and polymeric insulators in this paper. The experimental results show that the polluted flashover voltage U
f is affected by equivalent salt deposit density ρESDD and nonsoluble deposit density ρNSDD, the influences of which are independent of each other. Based on the analyses of the flashover voltages, the correction formulas of the flashover voltages Uf of various insulators at various ρESDD and ρNSDD levels are pointed out. The experimental results also show that thereis a distinct difference among the flashover voltages of various types of polluted insulators. At the same pollution degree, the antipollution performance of the fog-type glass insulator is better than those of the outer-rib porcelain insulators. In terms of the effectiveness of creepage distance of insulators, the antipollution performance of polymeric insulators is superior to those of porcelain and glass insulators. [ABSTRACT FROM AUTHOR]- Published
- 2007
- Full Text
- View/download PDF
22. Positive Switching Impulse Discharge Performance and Voltage Correction of 1-m Rod-Plane Air Gap.
- Author
-
Jianlin Hu, Xingliang Jiang, Shaohua Wang, Zhijin Zhang, Caixin Sun, Lichun Shu, and Jun Wang
- Subjects
HIGH voltages ,ELECTRICAL engineering ,ELECTRIC potential ,POWER transmission ,POWER (Mechanics) ,POWER electronics - Abstract
Switching impulse discharge performance of air gaps at high altitudes, which is a fundamental in the extremely high voltage external insulation design, remains an unsolved key technology across the world. Due to the limited applicable range of ‘g’ parameter method recommended by IEC Publication 60-1(1989), this paper aims to explore the relationship between positive switching impulse 50% discharge voltage U
50 of rod-plane air gaps and atmospheric parameters, and proposes two new voltage correction methods based on the parameter ‘g’ and the atmospheric pressure ratio, respectively. The two methods have been proved by the experimental investigations carried out on 1-m rod-plane air gap both in the artificial climate chamber and at three spots of different high altitudes in this study. The results show that, if the additional influence of absolute humidity is considered, the positive switching impulse 50% discharge voltage U50 of rod-plane air gaps is a power function of relative pressure and relative air density; the ‘g’ parameter method in IEC Publication 60-1(1989) is not applicable to the regions with an altitude above 2000 m or the condition of h/δ > 15 g/m³ compared with the correction method based on the ‘g’ parameter method, the correction method based on relative atmospheric pressure has a wider applicable range and less error; when the absolute humidity increases 1 g/m³, U50 varies within the range of 1.0%–1.15%. [ABSTRACT FROM AUTHOR]- Published
- 2007
- Full Text
- View/download PDF
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