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Insulator (electricity)

About: Insulator (electricity) is a research topic. Over the lifetime, 15941 publications have been published within this topic receiving 108950 citations. The topic is also known as: electrical insulator.


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Journal ArticleDOI
TL;DR: In this article, various factors controlling flashover of solid insulators in pressurized SF6, are reviewed and their influences in gas insulated systems are discussed from a practical point of view.
Abstract: Various factors controlling the flashover of solid insulators in pressurized SF6, are reviewed and their influences in gas insulated systems are discussed from a practical point of view. Flashover voltage of clean insulator surface is under the influence of the insulator-metal contact as well as the macroscopic electric field distortion due to the high dielectric permittivity of solid insulator. Conducting particles or even fine metal powder can reduce the flashover voltage. Their effects are strongly dependent on the position they are located, the size of the insulator and gas pressure. Humidity of SF, gas should be strictly governed in SF, gas insulated apparatuses, since the condensation of water can decrease flashover voltage considerably. Decomposition products of SF6 due to the arcing in switchgears are deleterious to epoxy insulators particularly when silica is used as their filler. The decomposition products decrease the leakage resistance on the insulation surface. The field strength near positive electrode is enhanced by the electrolytic effect in the surface conduction layer. In some extreme condition, it initiates tracking on the insulator surface.

91 citations

Journal ArticleDOI
TL;DR: In Hydro-Quebec, an automatic measurement and recording of the electric field along the insulator string which decreases considerably in front of an internally-shorted insulator is performed as discussed by the authors.
Abstract: Until now at Hydro-Quebec, overhead power transmission line porcelain insulators had been tested by the buzz method which simply consists in applying a short-circuit to each insulator in a string and listening for a buzz-like sound indicating a good insulator. However, safety considerations that preclude short-circuiting insulators and other disadvantages of that method have led Hydro-Quebec to undertake and complete the development of a new insulator tester. The working principle of this new device is based on the automatic measurement and recording of the electric field along the insulator string which decreases considerably in front of an internally-shorted insulator. The tester is slid along the string while the insulators are counted automatically. The information from tests on up to 200 strings can be stored in the device to be later transferred in a host computer for interpretation and/or permanent storage. The new tester also gives information on voltage distribution along the insulator strings which can be useful for the design of future power transmission lines. >

90 citations

Journal ArticleDOI
TL;DR: In this article, the authors used an inclined plane (IP) tracking and erosion test under both positive and negative dc voltages for silicone rubber samples filled with micron and nano-sized particles to understand the phenomena occurring during such tests.
Abstract: In order to improve the tracking and erosion performance of outdoor polymeric silicone rubber (SR) insulators used in HV power transmission lines, micron sized inorganic fillers are usually added to the base SR matrix. In addition, insulators used in high voltage dc transmission lines are designed to have increased creepage distance to mitigate the tracking and erosion problems. ASTM D2303 standard gives a procedure for finding the tracking and erosion resistance of outdoor polymeric insulator weathershed material samples under laboratory conditions for ac voltages. In this paper, inclined plane (IP) tracking and erosion tests similar to ASTM D2303 were conducted under both positive and negative dc voltages for silicone rubber samples filled with micron and nano sized particles to understand the phenomena occurring during such tests. Micron sized Alumina Trihydrate (ATH) and nano sized alumina fillers were added to silicone rubber matrix to improve the resistance to tracking and erosion. The leakage current during the tests and the eroded mass at the end of the tests were monitored. Scanning Electron Microscopy (SEM) and Energy dispersive Xray (EDX) studies were conducted to understand the filler dispersion and the changes in surface morphology in both nanocomposite and microcomposite samples. The results suggest that nanocomposites performed better than microcomposites even for a small filler loading (4%) for both positive and negative dc stresses. It was also seen that the tracking and erosion performance of silicone rubber is better under negative dc as compared to positive dc voltage. EDX studies showed migration of different ions onto the surface of the sample during the IP test under positive dc which has led to an inferior performance as compared to the performance under negative dc.

90 citations

Journal ArticleDOI
Xingliang Jiang1, Jihe Yuan1, Lichun Shu1, Zhijin Zhang1, Jianlin Hu1, Feng Mao1 
TL;DR: 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.
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.

89 citations

Journal ArticleDOI
E. A. Cherney1
TL;DR: In this paper, the 60 Hz flashover performance of 230 kV and 500 kV long-rod polymer insulators is compared to standard ceramic suspension insulator strings under moderate ice conditions.
Abstract: The 60 Hz flashover performance of 230 kV and 500 kV long-rod polymer insulators is compared to standard ceramic suspension insulator strings under moderate ice conditions. The tests on clean and heavily pre-contaminated insulators were performed indoors to minimize the effects of wind and temperature variations. In general, contaminated and iced long-rod insulators with disc-shaped sheds of uniform diameter do not perform as well as insulators having conical- shaped sheds of alternating diameters. All 230 kV long-rod insulators tested show an improved performance over conventional ceramic insulation of equivalent length. At 500 kV, only those long-rod polymer insulators that have conical-shaped sheds of alternating diameters show an improved performance over conventional ceramic insulation. A mechanism describing the flashover of contaminated and iced insulators is proposed and discussed in relation to long-rod insulator designs and performance.

89 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023368
2022892
2021224
2020478
2019561
2018629