How to choose insulators

Insulator is one of the indispensable components in power system, which is widely used in transmission lines, substations, electrical equipment and other occasions. Its main function is to realize the electrical isolation between conductors and the ground or other conductors, while bearing mechanical loads. Therefore, the correct selection of insulators is of great significance to ensure the safe and stable operation of power system.

First, according to the voltage level selection

The selection of insulators should first consider the voltage level of power system. Different voltage levels have different requirements on insulation performance, mechanical strength and leakage distance of insulators. Generally speaking, porcelain or composite insulators can be used in low-voltage distribution systems; In the medium and high voltage transmission lines, it is necessary to choose suspension insulators or composite insulators with higher insulation performance and mechanical strength. In addition, with the development of UHV transmission technology, the requirements for insulators are further improved, and products with excellent voltage resistance and aging resistance must be selected.

Second, choose according to environmental conditions

Environmental factors are one of the important factors that affect the performance of insulators. For example, in areas with high humidity, salt fog, serious dust or serious pollution, silicone rubber composite insulators with good anti-pollution flashover performance should be preferred, because their surface hydrophobicity is good, which can effectively prevent flashover accidents caused by pollution. In cold regions, the frost resistance of insulators and the stability of materials at low temperature should be considered.

Third, according to the installation method.

Insulators have many installation forms, such as disc, rod, column, sleeve and suspension, and different installation methods are suitable for different application scenarios. For example, suspension insulator strings are usually used on transmission towers to bear the tension of wires; In substations, column or bushing insulators are often used to support buses or circuit breakers.

Four, according to the mechanical strength and electrical performance selection.

Insulators not only bear certain electrical loads, but also mechanical stresses such as wind pressure, conductor tension and ice load. Therefore, the required mechanical strength should be calculated according to the actual stress situation, and a certain safety margin should be left. In terms of electrical performance, it is necessary to pay attention to whether the parameters such as power frequency withstand voltage, impact withstand voltage and leakage current meet the system requirements.

Five, comprehensive consideration of economy and maintenance costs

On the premise of meeting the technical requirements, the cost performance of insulators should also be considered comprehensively. Although the initial investment of composite insulator may be slightly higher, it is free of cleaning, long maintenance period and low overall operating cost, so it is suitable for use in complex environment. Although the price of traditional porcelain insulators is low, they need to be cleaned frequently in high pollution areas, and the maintenance workload is heavy.

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To sum up, the selection of insulators is a technical and economic work, which must be comprehensively evaluated according to voltage grade, environmental conditions, installation methods, mechanical and electrical performance requirements, and maintenance costs. Only by selecting insulators scientifically and reasonably can the reliability and safety of power system be effectively improved and the stable and efficient operation of power transmission be guaranteed.