| 摘要 |
An electrical insulator of the umbrella type comprising an insulating supporting stem end at least one insulating umbrella mounted on the stem, in which the umbrellas are formed by first arranging an insulating mould umbrella on the stem to define a cavity between the mold umbrella and the stem and then filling the cavity at least partly with a hardenable insulating synthetic material. When hardened, the material completes the formation of the umbrella with the mould, and also secures the umbrella to the stem. Arrangements for increasing the surface leakage path are described, using an annular sleeve which can be inserted into the mould umbrella, or by using a cover which can be placed on the mould umbrella. A sealing arrangement between the inner part of the mould umbrella and the stem to prevent loss of the hardenable synthetic material is also described. In the method for making the insulators, a variety of synthetic materials may be employed, both for the filling material and for the mould umbrellas themselves, such as cycloaliphatic epoxy resins, silicone rubber, the mould umbrellas may also be of butyl rubber, fluorosilicone or polysulfide. |
