With the continuous progress of the economy and society and the continuous acceleration of the urbanization process, the traditional overhead wires can no longer meet the needs of social development, so the cables buried in the ground came into being. Due to the particularity of the environment in which the underground cable is located, the cable is very likely to be corroded by water, so it is necessary to add a water blocking tape during the manufacture to protect the cable.
The semi-conductive cushion water blocking tape is compounded with semi-conductive polyester fiber non-woven fabric, semi-conductive adhesive, high-speed expansion water-absorbing resin, semi-conductive fluffy cotton and other materials. It is often used in the protective sheath of power cables, and plays the role of uniform electric field, water blocking, cushioning, shielding, etc. It is an effective protective barrier for power cable and has important significance for prolonging the service life of cable.
During the operation of the high-voltage cable, due to the strong current of the cable core in the power frequency field, impurities, pores and water seepage in the insulation layer will occur, so that the cable will be broken down in the insulation layer during the operation of the cable. The cable core will have temperature differences during the working process, and the metal sheath will expand and contract due to thermal expansion and contraction. In order to adapt to the thermal expansion and contraction phenomenon of the metal sheath, it is necessary to leave a gap in its interior. This provides the possibility of water leakage, which leads to breakdown accidents. Therefore, it is necessary to use a water-blocking material with greater elasticity, which can change with temperature while playing a water blocking role.
Specifically, the semi-conductive cushion water blocking tape consists of three parts, the upper layer is a semi-conductive base material with good tensile and temperature resistance, the lower layer is a relatively fluffy semi-conductive base material, and the middle is a semi-conductive resistance water material. In the manufacturing process, firstly, the semi-conductive adhesive is uniformly attached to the base fabric by means of pad dyeing or coating, and the base fabric material is selected as polyester non-woven fabric and bentonite cotton, etc. The semi-conductive mixture is then fixed in the two semi-conductive base layers by adhesive, and the material of the semi-conductive mixture is selected from polyacrylamide/polyacrylate copolymer to form high water absorption value and conductive carbon black and so on. The semi-conductive cushion water blocking tape composed of two layers of semi-conductive base material and a layer of semi-conductive resistive water material can be cut into tape or twisted into rope after being cut into tape.
In order to ensure the effective use of the water blocking tape, the water blocking tape needs to be stored in a dry warehouse, away from fire source and direct sunlight. The effective date of storage is 6 months from the date of manufacture. During storage and transportation, attention should be paid to avoid moisture and mechanical damage to the water blocking tape.