Some Basic Knowledge about Insulators

1. Requirements for insulator crimping equipment and mould

The technical requirements of the insulator crimping machine mainly include pressure relay, equipment accuracy, control principle, etc., among which the pressure relay is required to be ≥500T, and the equipment accuracy is less than 0.05mm. Dual control of pressure and compression quantity is adopted, and the crimping procedure can be set for flexible crimping. At present, foreign Germany, and Finland crimping machines meet the requirements, of high precision equipment, high pressure, convenient control, and beautiful appearance, but foreign equipment is expensive and delivery time is long, and after-sales technical support is not enough.

The crimping die is configured by the supplier of the crimping machine, and the material is C12 after vacuum heat treatment and spheroidization treatment, to ensure the stiffness, hardness and wear resistance of the material so that the deformation of the material is small and the service life is long. According to experience, the inner diameter of the pressing block is 0.5mm larger than the corresponding outer diameter of the short distance, and the crimping effect is the best.

2. What should we pay attention to in the crimping process of insulators?

It mainly includes the pressure relay, the compression amount, the pressing speed and the holding time. Because of the size of the mandrel, the cumulative error can reach 0.2mm. According to the experience, 0.05mm compression error may cause more than 10% error impact on the compression strength, therefore, the pressure will be the main process, according to the mandrel breaking pressure and empirical formula, determine the appropriate pressure relay; In order to reduce the influence of material fluctuation of mandrel and tool, the compression quantity is controlled. The pressing speed should not be fast, and the plastic deformation of the instrument should be sufficient in the slow pressing process, while the holding time should not be too long to prevent the core rod from breaking. The optimal experience time is about 2s.

3. How to seal the insulator end?

The end seal is one of the key technologies of all composite insulators, which directly affects the long-term reliability of the products. If the end seal is not good, moisture is easy to invade the sealing interface, and hydrofluoric acid is generated under the action of the strong electric field to corrode the glass fibre in the mandrel, which eventually leads to the brittle break of the mandrel and the composite insulator hanging string, resulting in power grid accidents. Therefore, the end seal is another key index of product quality.

Drawing on the advanced experience in the sealing of the end of composite insulators, the sealing structure is improved, the sawtooth groove is added, the whole injection coating process is adopted, and the chemical cross-linking reaction is generated between the core rod, the gold tools and the silicone rubber through the bottom coating, so as to achieve a higher bonding effect and improve the reliability of the interface sealing.

4. Structure design of 110kV insulator umbrella sleeve

The structure of "one big umbrella and two small umbrellas" (as shown in the figure below) with good anti-fouling and anti-wetting performance is adopted. The spacing, extension and dip Angle of an umbrella are reasonably designed to meet the needs of process and external insulation to the maximum.