Common specifications and models of overhead cables
Selection of insulation materials for Aerial Bundled Cable
Aerial Bundled Cable is to wrap the insulating material outside the conductor with different thicknesses according to the requirements of its withstand voltage, which plays a role in isolating the wire from the outside world. After the insulated wire is energized, it will generate heat, so the selection of insulating materials has advantages in heat resistance, aging resistance, thermal conductivity and mechanical properties. The insulation materials used in insulated wires are generally weather-resistant polyvinyl chloride, polyethylene, high-density polyethylene, cross-linked polyethylene, etc., which are black mixtures.
1. Polyvinyl chloride insulating material (PVC): It has good electrical and mechanical properties, relatively stable to acid and alkali organic chemical components, moisture-resistant, flame-retardant, low cost and easy to process. However, compared with other insulating materials, it has low insulation resistance and poor heat resistance. Its long-term allowable working temperature should not exceed 70°C. Therefore, PVC insulation materials are generally only suitable for the outer sheath of low-voltage insulated wires or cluster-type insulated wires.
2. Polyethylene insulation material (PE): It has excellent electrical properties, good chemical stability, good solubility resistance at room temperature, very stable performance against non-oxygen acids and alkalis, and good moisture resistance and cold resistance. However, the softening temperature of PVC insulation material is relatively low, and its long-term allowable working temperature should not exceed 70°C. In addition, environmental stress cracking resistance, oil resistance and weather resistance are relatively poor, and it is not flame retardant.
3. High-density polyethylene insulation material (HDPE): except that its long-term allowable work temperature should not exceed 70°C and it is not flame-retardant, its other main electrical and mechanical properties are close to those of cross-linked polyethylene materials.
4. Cross-linked polyethylene insulation material (XLPE): It is formed by converting the linear molecular structure of polyethylene into a network structure by cross-linking. Its electrical performance is close to that of polyethylene, and it has good heat resistance. Its long-term allowable working temperature is 90°C. It has strong overload resistance and can avoid environmental stress cracking. Its mechanical and physical properties are better than PVC (polyvinyl chloride) and PE insulation materials. good.
Common specifications and models of overhead cables
1. The following types are overhead and fixed soft copper core products used for transformer down-conductors; when the cable is erected, a certain distance between the cable and the trees should be considered, and frequent contact between the cable and the trees should be allowed when the cable is running.
JKL Copper Core Polyethylene Insulated Aerial Cable
JKLY aluminum core polyethylene insulated overhead cable
JKYJ copper core XLPE insulated overhead cable
JKTRYJ soft copper core XLPE insulated overhead cable
JKLYJ aluminum core XLPE insulated overhead cable
JKLHYJ aluminum alloy core XLPE insulated overhead cable
JKTRY soft copper core polyethylene insulated overhead cable
JKLHY aluminum alloy core polyethylene insulated overhead cable
2. Aerial and fixed soft copper core products are used for transformer down-conductors; when cables are erected, a certain distance between cables and trees should be considered, and frequent contact between cables and trees should be allowed when cables are running.
JKLYJ/B soft core natural color XLPE insulated overhead cable
JKLHYJ/B aluminum alloy core natural color XLPE insulated overhead cable
The types of these types of Aerial Bundled Cable are the most common types of overhead insulated cables in life, and the appropriate cable products are selected according to the scene of use.
What should be paid attention to in the construction of overhead insulated conductors?
1. The insulation resistance of the insulated overhead wires should be telemetered before and after pouring, so as to detect the insulation damage of the overhead insulated wires during transportation and setting out as early as possible.
2. The erection of insulated overhead conductors should be carried out in dry weather. The temperature should be in accordance with the requirements of the insulated wire manufacturer. Setting-out construction should be avoided in rainy and snowy weather. When laying out wires, the insulated overhead wires must not be dragged on the ground, pole towers, crossarms, porcelain bottles or other objects, so as not to damage the wire insulation layer.
3. After the insulation layer of the overhead insulated wire is damaged, when the damage depth of the insulation layer is more than 10% of the thickness of the insulation layer, the insulation reinforcement treatment must be carried out, and then it can be repaired by wrapping it with insulating self-adhesive tape. Pay attention to dustproof and waterproof when winding. The thickness of the repair should be greater than the damage depth of the insulation layer, and should not be less than two layers, and the severely damaged parts should not be less than five layers.
4. If the cable is directly buried, pay attention to the soil conditions. The burial depth of cables under buildings should generally not be less than 0.3m. If the surrounding environment is soft or complicated, such as cultivated land, construction sites or roads, a certain burial depth (0.7 ~ 1m) should be provided to prevent accidental damage to direct buried cables. If necessary, clear signs shall be erected.
In general, the diameter of the insulating sheath should be 1.5 to 2.0 times the diameter of the connecting pipe at the treatment site. For medium voltage insulated wires, the inner and outer insulating sheaths should be used for insulation treatment. At the same time, the junction must be shielded. The wire joints should be tight, firm and beautiful, and there should be no overlapping, bending, cracks or protrusions.