The
electrical insulators is an important part of the power system, it plays the role of supporting the wire and insulating the insulation between the wire and the support. The working principle of Electrical insulators is to use the insulation properties of insulating materials to prevent the flow of current. When the wire passes through the electrical insulators, due to the insulating effect of the electrical insulators, the current cannot flow through the electrical insulators to the support, thus ensuring the safe operation of the power system. At the same time, The electrical insulators can also withstand the mechanical load to ensure the safe support and insulation of the wire.
The structure of The electrical insulators is generally composed of three parts:
The electrical insulators head, The electrical insulators post and The electrical insulators holder. The electrical insulators head is the upper part of The electrical insulators, which is used to connect wires and is usually made of an insulating material such as porcelain or glass fiber reinforced plastic. The electrical insulators post is the main part of The electrical insulators, which plays the role of support and insulation, and is usually made of materials such as porcelain or glass fiber reinforced plastic. The electrical insulators holder is the lower part of The electrical insulators, which is used to connect the support, and is also made of insulating material. This structure design can effectively isolate the wire and bracket, and ensure the safe operation of the power system.
The material of electrical insulators is the key to ensure its insulation performance. Common electrical insulators materials include porcelain, glass fiber reinforced plastic and so on. The porcelain electrical insulators has good mechanical strength and voltage resistance, which is suitable for high voltage transmission lines. The glass fiber reinforced plastic electrical insulators has the advantages of light weight, easy installation and so on, which is suitable for distributed power system. These materials can effectively stop the flow of current and ensure the safe and stable operation of the power system
Classification of Electrical insulators:
According to the different installation methods, Electrical insulators can be divided into suspension Electrical insulators and pillar Electrical insulators; According to the different insulating materials used, it can be divided into porcelain Electrical insulators, glass Electrical insulators and composite Electrical insulators (also known as synthetic Electrical insulators); According to the use of different voltage levels, can be divided into low-voltage electrical insulators and high-voltage electrical insulators; According to the different environmental conditions of use, the anti-pollution electric insulators used in dirty areas are derived; According to the different types of voltage used, DC electrical insulators is derived; There are a variety of special purpose Electrical insulators, such as insulation cross arm, semiconductor glaze Electrical insulators and power distribution tension Electrical insulators, spool Electrical insulators and wiring Electrical insulators. In addition, according to the different breakdown possibilities of insulating parts, it can be divided into two categories: type A, that is, non-disruptive electrical insulators and type B, that can be disruptive electrical insulators.
There are often a lot of dirty particles on the surface of porcelain Electrical insulators in dirty areas, and these dirty particles will form conductive liquid film on the surface of porcelain when wet, so that the voltage resistance of porcelain insulation is significantly reduced, and the flashover voltage becomes very low, which is the reason why porcelain insulation is easy to flashover under dirty and wet conditions. Dirt and tide are the necessary conditions for dirt flashover, porcelain insulation only dirty and not wet will not cause flashover. In wet weather, dirty Electrical insulators are prone to flashover discharge, so they must be cleaned to restore the original insulation level, the general area is cleaned once a year, and the dirty area is cleaned twice a year.
With the passage of time, the outdoor wind and sun, long-term voltage effect, there may be individual Electrical insulators are not insulated, can not play the role of insulation. Because the insulation of The electrical insulators is destroyed, the insulation resistance is close to 0, and the voltage value borne on The electrical insulators string is also close to 0, it is called "zero value electrical insulators". If The electrical insulators that has been broken down is not replaced in time, multiple damage will occur, and the operation is extremely dangerous. It may occur that the wire voltage will break down all the good Electrical insulators (residual Electrical insulators) and lead to single-phase grounding, affecting the normal power supply. In order to prevent the above situation, it is necessary to measure regularly and find out the bad electrical insulators. In order to ensure the continuous reliability of power supply and not power outage test, the method of measuring Electrical insulators on line can be used. At present, the gap discharge method is commonly used to test. When measuring, the two electrodes on the test rod contact the two ends of The electrical insulators (metal part), according to the size of the spark gap discharge spark to judge the quality of The electrical insulators, such as no spark, this is a zero value electrical insulators.
The principle of spark gap detection of Electrical insulators: Whether the spark gap on the test rod can be broken down by the distributed voltage on The electrical insulators during the test operation can be used to determine whether The electrical insulators is deteriorated. The detection is mainly based on the "horn" discharge sound emitted by the gap. When the discharge sound is not heard and The electrical insulators with zero value is found, to avoid bad contact between the probe and the steel cap of The electrical insulators, or the discharge sound cannot be heard clearly in the wind, repeat the test several times to ensure correct judgment.
When using a spark gap detector to detect Electrical insulators with live power, the following requirements should be observed:
1) Before detection, the detector should be detected to ensure flexible operation and accurate measurement.
2) Pin type and suspended Electrical insulators with less than 3 pieces shall not be tested by spark gap detector.
3) When testing The electrical insulators string of 35KV and above voltage level, when the number of zero-value electrical insulators pieces in the same string is found to reach the specified number, the detection should be stopped immediately to prevent unsafe situations.
In general, the number of Electrical insulators can most accurately judge the voltage level. Each piece of electrical insulators is about 15 centimeters thick. Seven pieces are about one meter. According to the actual situation, the number of Electrical insulators corresponding to each voltage level is as follows: 750 kV: 32 500 kV: 23-25 330 kV: 17 220 kV: 13 110 kV: 7 66 kV: 5 35 kV: In practical applications, if it is high altitude, dirty areas or important towers, the number of Electrical insulators may need to be increased by several pieces. With the increase of voltage level, the nonlinearity of pressure is stronger, in fact, there may be differences in the number of Electrical insulators in different regions and different environments.
