The casing is mainly composed of a capacitor core, a oil pillow, a flange, and an upper and lower porcelain sleeve. The main insulation is a capacitor core, which is formed by connecting concentric capacitors in series, and is sealed in a sealed container composed of upper and lower porcelain sleeves, oil pillows, flanges and bases. The container is filled with treated transformer oil to make the internal main insulation a structure of oil paper. The contact surface between the main components of the casing is lined with oil-resistant rubber gaskets, and the components are fully sealed by the central pressing force exerted by a set of strong springs disposed in the oil conservator. The flange is provided with a venting plug, an oil taking device, a measuring device for dielectric loss (tan δ, referred to as dielectric loss) and partial discharge (referred to as partial discharge). The cover of the measuring device during operation must be covered to ensure that the final screen is grounded and open circuit is strictly prohibited.

The connection between the bushing and the high-voltage lead of the transformer has two ways: cable-through and guide-bar current-carrying.