Technical Basis For External Installation Of Insulating Covers Of Insulators

suspension type insulator The upper metal cap adopts a ball-and-socket or groove design, with standardized outer diameters of Φ16, Φ20, or Φ24 mm. The inner diameter of the insulating cover maintains a 0.5-1 mm fit clearance with the outer diameter of the metal cap, secured by elastic clips or threaded locking. The surface of the upper metal cap is hot-dip galvanized or Dacromet treated, with a roughness controlled within Ra6.3, ensuring a tight fit with the rubber sealing ring on the inner wall of the cover. composite tension insulator During operation, the metal cap withstands mechanical tensile and torsional stresses. The cover, mounted externally, does not interfere with the bonding interface between the cap and the insulating ceramic component, maintaining its original mechanical strength.

high voltage transmission line insulators In high-voltage lines, where power frequency voltage and lightning impulse voltage are applied, the connection between the upper metal cap and the conductor forms a concentrated electric field area. The insulating cover is made of silicone rubber or EPDM material with a relative permittivity between 3 and 4. When mounted externally on the metal cap, it adds a composite insulation layer of air and solid dielectric. The umbrella-shaped structure of the shield extends the surface discharge path, and in dirty or humid environments, the hydrophobic surface prevents the formation of continuous conductive channels by the dirt layer. The creepage distance of the overhead power line insulators has been increased from the original 20 mm/kV to over 28 mm/kV.