Wall casing is also called wall casing, waterproof casing, wall embedded pipe, and waterproof casing is divided into rigid waterproof casing and flexible waterproof casing. The AC wall bushing used for electric conduction is called AC wall bushing, which can be divided into dry capacitive AC wall bushing and porcelain insulated AC wall bushing, referred to as silicone rubber bushing and porcelain bushing respectively. Wall-through porcelain bushings are suitable for power stations, substations, power distribution devices and high-voltage electrical appliances with power frequency AC voltage below 35kV. They are used as insulation and support for conductive parts passing through walls or other grounding objects. The bushings are suitable for ambient temperature -40～+40℃. Wall-through porcelain bushings are divided into outdoor and indoor according to the installation location. According to the structure, it is divided into a guide rod type and a busbar type. According to the conductor material used, it is divided into aluminum conductor and copper conductor. According to the installation location, it is divided into ordinary type and pollution-resistant type. Selection of wall bushings 1. Type and type selection According to the installation location, indoor type and outdoor type can be selected. According to the application, wall bushings with conductors and busbar . Indoor power distribution devices generally use aluminum conductor wall bushings. 2. The rated voltage is selected according to the condition that the rated voltage of the wall bushing shall not be lower than the rated voltage of the power grid where it is located. When there is ice and snow, the 3~20kV outdoor wall bushing should choose a product with a higher voltage. For 3-6kV, products with two-level voltage increase can also be used. 3. The rated current is to choose the wall bushing with conductor, and its rated current shall not be less than the maximum continuous working current of the circuit. The busbar type wall bushing itself has no conductors, so there is no problem with the selection of rated current, but the size of the busbar allowed to pass through the window should be checked. Model description of high voltage wall bushing: C-------indoor copper conductor wall bushing; F-------composite dry wall bushing; CL------ Indoor Aluminum Conductor Wall Bushing; CW---Outdoor-Indoor Copper Conductor Wall Bushing; CWW---Outdoor-Indoor Copper Conductor Wall Bushing; CWL---- -outdoor-indoor aluminum conductor wall bushing; CWWL-outdoor-indoor anti-pollution aluminum conductor wall bushing; CM-------indoor busbar wall bushing; CMMW-outdoor- Indoor pollution-resistant busbar through-wall porcelain bushing; 1. Each has the advantages of small size, light weight, and convenient transportation. 2. Each composite insulator has high mechanical strength, reliable structure, stable performance, and high safety margin to ensure safe operation of the circuit. 3. Each composite electrical insulator has superior performance, good hydrophobicity and mobility, and stain resistance 4. It has good anti-pollution flashover ability, and can operate safely in heavily polluted areas without manual cleaning, avoiding measurement zero point 5. Every A composite insulator has acid resistance, alkali resistance, heat aging resistance and capacitance resistance, good sealing performance, and can ensure insulation moisture and so on. 6. Anti-brittleness, earthquake strength, no brittle fracture accidents. Environmental conditions: 1) Indoor casing The ambient temperature is not higher than+40 ℃ and not lower than - 40 ℃ The altitude does not exceed 1000 m Monthly average value of relative humidity is not more than 90% The surrounding air shall be free from corrosive or obvious pollution such as combustible gas and water vapor No frequent violent vibration 2) Outdoor casing The ambient temperature shall not be higher than+40 ℃ and not lower than - 40 ℃; The altitude shall not exceed 1000 m; The wind speed is not more than 34m/s According to GB/T5582, the air pollution degree of the product's use environment is divided into four levels: I, II, III and IV; No frequent violent vibrationUse and classification: The casing is composed of porcelain parts, metal accessories, mounting flanges and conductive bars (rods). Wall-through porcelain bushings are used for power distribution devices and high-voltage electrical appliances in power stations and substations, for wires to pass through grounding partitions, walls or electrical equipment enclosures, and to support conductive parts to insulate them from the ground or the enclosure. Wall-through porcelain bushings can be divided into indoor and outdoor wall-through porcelain bushings according to their use environment. According to the different conductors passing through its center, it can be divided into busbar through-wall porcelain bushing, copper conductor through-wall porcelain bushing and aluminum conductor through-wall porcelain bushing. When the copper conductor is directly connected to the busbar, galvanic corrosion is easy to occur, and the temperature rise of the contact surface is too high, which will cause the joint to burn out and affect the life of the equipment. Therefore, copper-aluminum transition joints should be used, but it will bring trouble to the site construction. The casing can solve the above problems. Indoor and outdoor wall-through porcelain bushings are assembled from porcelain parts, conductive rods, metal accessories at both ends and mounting flanges. The busbar wall-through porcelain bushing is assembled from porcelain parts, metal accessories at both ends, busbar splint and mounting flange (the busbar splint is usually prepared by the user according to the size of the busbar). Instructions for installation and use: 1. The through-wall porcelain bushing is suitable for the distribution equipment of power stations and substations where the rated power frequency AC power is below 40.5kv, the ambient temperature of the installation site is -40°C~+40°C, and the altitude does not exceed 1000m. 2. Indoor wall bushings are not suitable for places where the enamel, metal accessories and cement adhesive of the bushing are damaged or are enough to reduce the electrical performance of the bushing. 3. If partial discharge occurs during the operation of the through-wall porcelain bushing, check whether there is any partial shedding of the aluminum sprayed layer at the flange or inner cavity of the porcelain bushing, and if so, take temporary pressure equalization measures in time. 4. The wall hole for installing the busbar through-wall porcelain bushing should be opened according to the large size of its flange reinforcement.