Composite Post Insulator

Improvements in electrode shape

The average breakdown field strength of uniform electric field and slightly inhomogeneous electric field gap is much higher than that of extremely inhomogeneous electric field gap. Generally speaking, the more uniform the electric field distribution, the higher the average breakdown field strength. Therefore, the electrode shape can be improved and the electrode curvature radius can be increased to improve the electric field distribution and increase the breakdown voltage of the gap. At the same time, the electrode surface should try to avoid burrs, edges, etc. to eliminate the phenomenon of local enhancement of the electric field. If an extremely non-uniform electric field is unavoidable, a symmetrical electric field (rod-rod type) should be used whenever possible.

Even if the electric field is extremely uneven, in many cases, in order to avoid strong corona discharge under the operating voltage, the electrode curvature radius must be increased.

Figure 2-25 shows some methods of changing the shape of the electrode to adjust the electric field. These methods can be summarized as follows: 

(1) Increase the radius of curvature of the electrode: For example, add a spherical shield to the end of the transformer bushing (see Figure 2-25(a)), use expanded diameter wires (the cross-section is the same, the radius is increased, see figure 2-25(b)), etc., use the method of increasing the electrode curvature radius to reduce the surface field strength.

(2) Improve the electrode edge: The electrode edge should be made into an arc, or try to make it as close as possible to an equipotential surface (see Figure 2-25(c)) to eliminate the edge effect.

(3) Make the electrode have the best shape; such as adding a metal flat ball to the high-voltage lead through the wall, and the edge of the wall hole is made into a rotating body similar to a vertical chain line (see Figure 2-25(d)), so as to improve its electric field distribution.

Adjusting the electric field and reducing the local excessively high field strength are effective measures to improve the electric strength not only for the gas gap but also for other insulation structures. For different insulation structures, in addition to improving the electrode shape, other methods of adjusting the electric field can also be used.

solid insulating covering

In a slightly uneven electric field, covering the surface of the high-field-strength electrode with a solid paper insulating layer can also increase the gap breakdown voltage, and the covering layer has a significant effect on increasing the air gap breakdown voltage, but covering the counter electrode with an insulating layer , to improve the air gap breakdown voltage research needs to be further in-depth.

Insulator designed mainly for flexural loads (bending) but also tension and compression, thus having combined loading capability. Normally utilized as a single unit can also be a double insulator assembly. Composite materials are most suitable for the application on compact lines and retrofitting due to their flexibility, overloads absorption capacity and reduced weight. We have thousands of pieces line post from 33kV to 362kV worked on lines all over the world, and there is no single accidents happens. 

We have our own silicone rubber workshop and lab. Each batch of rubber shall be tested and we have our own formula which makes our insulator tracking and earsion performance stable and good. Below is the key parameter of our rubber. 

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