Electric Pole Insulator 69kV

Electric Pole Insulator

1. System voltage: 69kV 

2. Maximum system voltage: 72.5kV

3. Frequency: 60Hz

4. Insulator length: 814mm

5. Creepage distance: 1895mm

6. Specified mechanical load: 26.8kN

7. Power frequency withstand voltage (Dry/Wet): 200kV/170kV

8. Lightning impulse withstand voltage: 385kV

1. Structure

Composite Line Post Insulator is made up by housing, core rod and end fittings mainly. Product structure as below picture shows:

2. Performance

2.1.1 The silicone rubber housing taken shape by whole injection. It has good hydrophobicity, hydrophobicity migration and soil resistance, as well as excellent electrical insulation properties and aging resistance, which could prevent effectively those accidents of pollution flash-over so as to ensure the safe running of high voltage transmission lines.

2.1.2 The modified ECR fiberglass reinforced epoxy resin rod is used as it has good resistance to high temperature, stress corrosion & acid attack, as well as fine damping action, high tensile strength (> 600Mpa), about 1.4 to 2 times the strength of ordinary steel, 5 times the porcelain, and resistance to creep and fatigue failure, which effectively ensure the internal insulation quality and mechanical strength of insulators. 

 In the operation and maintenance of insulators, the focus of the current research and hot issues are: 

(1) the zero value of porcelain insulators on-line detection problems, so far has not found a simple and reliable method.

method. 

(2) composite insulators running health state of online monitoring methods, in addition to visual inspection of surface water repellency, monitoring leakage current, has not yet found an effective method. 

(3) composite insulator brittle break and unexplained flashover problem, although the research on these two issues has made great progress, but has not yet been resolved.

(4) to prevent insulator dirt flashover problem, practice shows that in the porcelain or glass insulator surface coating RTV silicone rubber water-repellent coating, is an effective anti-fouling measures. The anti-fouling flash mechanism and life judgment of RTV silicone rubber hydrophobic coatings and online monitoring are still hot research issues.

Composite insulators and RTV silicone rubber water-repellent coatings as a representative of the organic outer insulation has been widely used, due to the excellent resistance to dirt flash and favored by users. Composite insulators have been developed from line suspension to power station pillar insulators and bushings, RTV silicone rubber water-repellent coatings have also been developed from the application in substations to the application of transmission lines. Because of China's air pollution is still unresolved, flash accidents are still plagued by the main problem of safe operation of power systems, so the two technologies in China's rapid development of composite insulators in the insulator market has occupied 1/3 share in some areas of China 100% of the substation has been coated with RTV silicone rubber water-repellent coatings, so the study of the organic insulation problem naturally become the focus of the external and hot issues!

Ion Migration Aging Problems of DC Insulators and Their Protection

DC insulators in the DC voltage there are some special properties need to be considered in the design process, such as the aging resistance of ceramic materials, steel foot corrosion problems. This is an important factor to ensure the reliable operation of DC insulators.

DC insulator porcelain formula and anti-aging performance research at home and abroad have more results. Currently for the porcelain insulator material in the DC voltage causes of aging, it is believed that the porcelain in the alkali metal ions, especially Na * ions in the migration process due to access to electrons and the formation of the volume than the ionic volume of two times the size of the atoms, the local expansion of the stress caused by the insulator rupture (mainly in the head of the insulator); another point of view that the ionic migration caused by the porcelain pieces of the internal resistivity of the conductive layer, resulting in uneven electric field distribution, the electric field distribution is not uniform, and the electric field distribution is not uniform. Resulting in uneven electric field distribution, after a long period of time and the role of the

Breakdown. Porcelain as a multi-phase system mainly composed of crystalline and glass phases such as materials, in which the electromechanical properties of the crystalline phase are generally very good, while the glass phase is the electromechanical properties of the weak phase is low, the performance of its ceramic is basically a combination of these two aspects. As the number of glass phase in the porcelain body accounts for about 50%, and, all the low melting point substances, such as alkali metal oxides NaO, K, etc. almost all into the glass phase, so the nature of the glass phase, how the performance of the porcelain has a decisive impact on the performance of the ceramic, especially for the DC insulating ceramic materials is more so. Can be said that the study of DC porcelain materials is actually the study of porcelain in the composition and content of the glass phase. In order to improve the aging resistance of DC porcelain insulators, taking into account the characteristics of the material and the traditional firing process, can be taken to change the structure and chemical composition of the glass phase, reduce the content of alkali metal ions and other measures.

Theory and practice have proved that the rational use of "neutralization effect" and "suppression effect" is an effective way to improve the resistivity of the porcelain, slow down the migration of ions to prevent aging, but not to increase the firing temperature. The so-called neutralization effect, that is, when the total concentration of alkali metal ions in the glass phase remains unchanged, containing two alkali metal ions of glass resistivity than only one alkali metal ions containing the glass resistivity to be larger, when the proportion of two alkali metal ions in the proportion of the case, the resistivity can be even increased by 4 to 5 orders of magnitude. And the effect is in the glass phase containing alkali metals add one or more alkaline earth metal oxides, can make the resistivity increase, the corresponding divalent cation volume, the stronger this effect. In the test through the use of neutralization and suppression effect makes the porcelain resistivity is improved.

According to the above principles, combined with the characteristics of the porcelain material of DC insulators to determine the porcelain formula design principles are as follows: the use of neutralization and suppression effect of the selection of suitable raw materials of melting and mineralizing agents, increase the ratio of potassium and sodium to reduce the Na2O content, to meet the process and the mechanical properties of the porcelain under the conditions of the design, so that the porcelain electrical resistivity increased to the highest in order to improve the aging resistance. According to the design principle of using burnt alumina - feldspar - viscous - mineralizer this new formulation system, after three rounds of formula test and verification, developed a in the DC voltage has excellent anti-aging properties, to meet the design requirements of DC insulators porcelain formula. Different clays, feldspars and mineralizers are selected through orthogonal design tests, and important indexes such as porcelain resistivity are determined through small sample tests to determine the raw materials used in the formulation; using regression equations and nonlinear planning theory, the variable rotation method is adopted to find out the clear relationship between the raw material ratios and the performance indexes.

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