Glass insulators are composed of glass shape, iron caps, steel feet, locking pins, cement adhesives, etc.
What requirements do these components need to meet?
- Insulation components of insulators:
1) Tempered glass components. Tempered glass components used as insulators shall comply with the provisions of JB/T 9678-2012 and GB/T 1001.1, and shall be dense without defects such as cracks, wrinkles, bubbles, impurities, and obvious collision marks. The surface shall have a uniform tempered layer, and all exposed glass surfaces shall be flat and smooth. Glass components should withstand 3 hot and cold impacts and at least 2 nickel sulfide homogenization treatments. The removal rate of the final nickel sulfide treatment should not exceed 0.5 ‰.
2) When glass insulation is used for the lines above the inter section of 800kV and above lines, the glass components should withstand no less than 3 hot and cold shocks and 2 nickel sulfide homogenization treatments. The removal rate of the last hot and cold shock should not exceed 5%, and the removal rate of the last nickel sulfide treatment should not exceed 0.3 ‰. In addition, for external umbrella shaped glass components, given the current manufacturing level, appearance defects such as external cracks and missing materials are not allowed. Slight deformation is allowed, but the degree of deformation does not exceed the standard allowable axial and radial offset range. The flying edge height and width should not exceed 0.8mm.
The strength of glass components should be verified by strengthening the iron cap steel feet, or the mechanical strength of the head should be inspected by stamping tests for tempered glass insulation components.
- B. Iron cap and steel feet
Iron caps and steel feet should meet the following requirements:
- 1) The iron cap of the insulator shall comply with the provisions of JB/T 8178, and the steel foot of the insulator shall comply with the provisions of JB/T 9677. All surfaces of metal components should be smooth, without protrusions or unevenness to prevent corona discharge.
2) The design of the iron cap and ball head should not yield or deform under the specified mechanical load, in order to avoid changing the structural height of the insulator or attaching other stresses to the insulation.
3) Iron caps can be made of heat treated malleable cast steel, malleable cast iron, or ductile iron, and should be free of cracks, wrinkles, pores, pinholes, burrs, or rough edges. The iron cap should be a circular ring with completely concentric inside and outside.
4) The design of the iron cap should facilitate the replacement of insulators with electricity.
5) Steel feet should be made of forged steel. All load-bearing surfaces should be smooth and uniform.
6) Iron caps and steel feet should not be manufactured using connection, welding, cold shrinkage crimping, or any other process involving more than one piece of material.
- C. Locking pin
1) The locking pin shall comply with the provisions of GB/T 25318 and GB/T 1001.1. Insulators with ball and socket connections should be equipped with reliable open locking devices. R-type pins should be used for 160kN and above. The R-shaped pin should have two separate ends to prevent it from completely coming out of the ball socket when locked and released.
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2) The locking pin should be made of austenitic stainless steel or other corrosion-resistant materials, and the material should not have a corrosion-resistant surface layer. It should be supplied as a complete set with the insulator. To prevent leakage, the size of the bent part at the end of the pin leg should strictly meet the standard requirements. According to GB/T 25318 for bending resistance verification, there should be no cracking after bending.
3) The assembly of locking pins should use specialized tools to avoid damaging the galvanized layer of metal accessories.
- D. Cement adhesive
Cement should meet the following requirements:
- 1) Insulators should be bonded using a binder made of Portland cement or high alumina cement with a strength grade of 52.5 or higher as specified in JB/T 4307. The exposed cement surface should be flat, with a flatness of no more than 2mm. There should be no non surface peeling cracks with a width exceeding 0.2mm on the cement surface, and no cracks that are clearly penetrated by water are allowed. Climbing patterns and surface fine cracks with a width less than 0.2mm are allowed. The surface of cement should not have large voids or pores. The manufacturing plant shall not use other materials to cover the surface of the cement adhesive.
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Jiangxi Huayao Electric Co., Ltd advantage products are glass insulators with a capacity of 40kN-550kN, which can meet the requirements of 10kV-500kV ultra-high voltage and extra high voltage transmission and transformation lines.
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