The casing is assembled from porcelain, mounting flanges and conductors. The busbar bushing does not have a conductive part. The porcelain sleeve and the flange fixing method except the 35kV high prototype and some products are mechanically mounted, and the rest are cemented with cement glue; the copper conductor is fixed by a centering washer and nut, copper The aluminum conductive row is fixed by a centering washer and a split pin. For the busbar wall bushings at both ends of the cover, the opening size is determined according to the selected busbar type. The surface of the accessory is painted with ash enamel.
In order to improve the initial corona of the casing, the 20, 35kV casing is subjected to pressure equalization measures on the structure, and the porcelain wall near the flange and the umbrellas (edges) on both sides are appropriately enlarged and thickened to be baked in the porcelain. A semiconductor glaze is uniformly placed on the inner cavity of the porcelain sleeve and the flange, and on the first umbrella (edge) near the flange. After firing, the semiconductor glaze is firmly bonded to the porcelain wall and is made through the contact piece. The short circuit of the porcelain wall greatly improves the electric field distribution, prevents the discharge of the casing cavity, and increases the flash discharge voltage.
The conductive part of the sleeve is made of aluminum conductor, which saves a lot of copper and reduces the cost. The conductive area connected to the busbar is increased, which overcomes the disadvantage that the contact area of the copper guide rod is small and the temperature is too high.
The casing mounting flange is divided into two types: positive and negative. In addition to the 6 and 10kV copper conductor tubes, the rest are reverse mounted.