Insulator is a special kind of insulating control, which can play an important role in overhead transmission line. Early years insulator for more poles, slowly development in high type high voltage wires to hang a lot at the end of the disc insulators, it is to increase the creepage distance, usually made of glass or ceramic call insulator. Insulator should not change due to environmental and electrical load conditions lead to a variety of electrical and mechanical stress and failure, or else there won't have a significant role in the insulator, will damage the whole line of use and operating life.
1. Insulators are usually divided into dielectric and unbreakable.
2. The structure can be divided into column type (pillar) insulator, suspension insulator, pin insulator, butterfly insulator, tension insulator, anti-pollution type insulator and casing insulator.
3. It is divided into line insulators and power stations and electrical insulators according to the application. There are pin type, butterfly shape, plate suspension, unbreakable type with horizontal and rod suspension. There are needle strut, hollow pillar and casing for the breakdown type insulator for power station and electric appliances, and the non-breakdown type has the rod and the container porcelain sleeve.
4. Insulators used in overhead lines, such as pin insulators, butterfly insulators, suspension insulators, porcelain crossers, rod insulators and tension insulators, etc.
5. The commonly used insulators are ceramic insulators, glass steel insulators, synthetic insulators and semiconductor insulators.
Maintenance and management
In wet weather, the dirty insulator is prone to flashover discharge, so it is necessary to clean up and restore the original insulation level. The general area is cleaned once a year and the polluted area is cleaned twice a year (before the fog season).
1. Power failure cleaning
The power cut is to wipe the worker's rod after the power failure. If wipe not net, can wipe with wet cloth, also can use scour scrubbing, if still scrubbed, should replace insulator or change synthetic insulator.
2. No power failure cleaning
It is usually used to brush or tie the insulator on the road line. The electrical properties and the effective length of the insulated rod, the distance between the person and the charged part shall be in accordance with the corresponding voltage grade, and the operation must be supervised by the special person.
3. Flush with charged water
There are two ways of flushing water and small water. Washing water, effective length of operation rod, distance between man and charged part must meet the requirements of industry regulations.
Insulator is one of the regulatory elements of eukaryotic biological genome and also a boundary element. The function is to prevent the proximity of the regulatory element and to enhance or inhibit the promoter of the gene that it defines. It has a polar effect on the inhibitory effect of the enhancer, i.e. it only inhibits the enhancement on the other side of the boundary and cannot suppress the enhancement of the same structure domain. The activity of insulator may be closely related to CTCF protein.
The role of insulators is directivity, which is found in the fly experiment. Fruit flies (D. Melanogaster) yellow loci on y into the transposon gypsy, cause y gene inactivation of some organizations, but some y gene is still active in the organization, its reason lies in the transposon gypsy an insulator sequence at one end. Gypsy had different effects on gene activity when he was inserted in different locus of the gene. This is because the y gene activity is regulated by the four enhancer, when the insulator is inserted in the upstream of the promoter, the wing shoulder (wing blade) and body epithelium (body cuticle) tissue block gene activation (from upstream enhancer), but not blocking in bristles (bristles) and fu (farsal claws) y gene expression in tissue (from downstream enhancer).
Because some enhancers are located upstream of the promoter, some are downstream, so the effect of insulators does not depend on the relative position of the insulator with the promoter. Therefore, the reasons for the direction of the insulator effect have not been fully understood. Two locus have been found to affect the function of insulators in the form of anti-activation. Gene S2J(Hw) coding of nuclear protein identification insulator, insulator and its combination of insulation. When the gene mutated, the insulator was inserted in the y locus, but the insulation was lost, and y was expressed in all tissues. Another loci is mod (MDG 4), the gene mutated, after its effect is just the reverse of Su (Hw), namely the type of these mutations are to enhance the insulation effect, make the insulation of the insulator effects no longer have directional and expanded, which is blocking the upstream and downstream sides to enhance the effect of the son. One explanation is that first Su(Hw) and insulator DNA combine to make insulators have an insulating effect. The mod(mdg4) combines with the Su(Hw) to cause the insulator to lose its insulating effect; The mutated mod(mdg4) cannot be combined with the Su (Hw), so the insulator enhances the insulation.