Pressed polymer insulators for low voltage overhead insulated conductors: Achieving safe and reliable overhead laying
Publish Time: 2024-12-03
In modern power systems, pressed polymer insulators for low voltage overhead insulated conductors, as an important transmission medium, bear the heavy responsibility of transmitting electrical energy from the power source to the user end. Its safety and reliability are not only related to the stable operation of the power system, but also directly affect the safety of people's lives and property.First of all, in the selection of the path of the overhead line, full consideration should be given to economy, safety and convenience. Avoid circuitous power supply and routes that hinder traffic, and ensure that the line can facilitate daily operation, maintenance and overhaul. When determining the path, attention should also be paid to the distance between the center of the pole and the edge of the road surface, which should usually be kept at about 0.5 meters, and ensure that the line edge is kept at a safe distance from permanent buildings at the maximum wind deflection. For bare wires and insulated wires, the horizontal safety distance from the building should be no less than 1 meter and 0.2 meters respectively, and the horizontal distance from the roadside trees should also be no less than 1 meter and 0.5 meters respectively.The selection and installation of poles are also crucial. Straight poles generally use steel poles with a taper of 1/75 because of their good stability. When installing the tension pole, a small cement pole can be used, and when there is no tension pole, a welded steel pipe pole can be used. The height of the pole should be such that the lowest conductor is at a maximum sag, and the distance from the ground in the residential area is greater than 6 meters, and it should not cross the building as much as possible. If it cannot be avoided, the vertical distance of the bare conductor at the maximum sag of the lowest conductor should be greater than 2.5 meters, and the insulated conductor should be greater than 2 meters.In terms of conductor arrangement, pressed polymer insulators for low voltage overhead insulated conductors are usually arranged horizontally, and the cross arm uses hot-dip galvanized equilateral angle steel with a minimum specification of 50×5. The distance between the conductors varies according to the span size. When the span is not greater than 50 meters, the distance between the bare conductor is 0.4 meters and the insulated conductor is 0.3 meters. The cross arm of the corner pole should be determined according to the stress conditions. A single cross arm can be used for corner poles below 15°, a double cross arm should be used for corner poles between 15° and 45°, and a cross cross arm should be used for corner poles above 45°.The selection of insulators also needs to be rigorous. Linear poles generally use porcelain pin insulators or porcelain cross arms, while tension poles use butterfly insulators or one-piece suspension insulators. Galvanized steel strands should be used for the guy wire. According to the cross section calculated by the force, the safety factor should not be less than 2, and the minimum specification is 35mm². The angle between the guy wire and the pole should be 45°, and should not be less than 30° when restricted by the terrain. The vertical distance of the guy wire across the road to the center of the road surface should not be less than 6 meters, and the inclination angle of the guy wire column should be 10° to 20°.In terms of wire connection, wires of different metals, different specifications, and different twist directions are strictly prohibited from being connected within the span. Aluminum stranded wire, aluminum alloy wire, steel core aluminum stranded wire, and steel stranded wire should be connected by crimping or jointing tube, and the surface dirt should be removed before connection, and electrical compound grease should be applied to prevent oxidation. Insulated conductors should be connected by special wire clamps and jointing tubes to ensure that the insulation cover after connection is protected from water ingress.In addition, the minimum safe distance between pressed polymer insulators for low voltage overhead insulated conductors and the surrounding environment should also be strictly controlled. In terms of cable laying, low-voltage cables and high-voltage cables should be laid separately. When laid side by side, the distance between them should not be less than 0.15 meters. The fixing of cables should be carried out according to design requirements, and it is strictly forbidden to use wire bundling. The bending radius of the cable should meet the specified requirements, and moisture-proof measures should be taken.In summary, the safe and reliable overhead laying of pressed polymer insulators for low voltage overhead insulated conductors requires comprehensive consideration and strict control from multiple aspects such as path selection, pole selection and installation, conductor arrangement and connection, insulator selection, wire setting, and cable laying. Only in this way can we ensure the stable operation of the power system and the safety of people's lives and property.
