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The use of overhead conductors has become commonplace in today’s daily life and production activities. With the development of technology and changes in demand, the types of cables are constantly enriched. In the mixed cable market, some unscrupulous manufacturers will take unqualified cable products. When put on the market, unqualified cables not only bring certain difficulties to the procurement of enterprises, but also bury hidden safety hazards in the normal operation of the power system. 1. Marking unqualified wires and cables: Marking is the main way for wires and cables to identify the basic information of products. According to the standard, the main content of the mark is: product model, specification, standard number, factory name, place of origin, etc. within a certain marking distance , When the mark is unqualified, it will cause the construction personnel to identify errors, and in serious cases, it will cause electrical accidents.
2. Wires and cables with unqualified structural dimensions: The main problem with structural dimensions is the thickness of the sheath. Insulation thickness. When the sheath and insulation thickness of the welding cable is not up to the standard, the electric resistance strength of the wire and cable will be seriously reduced, resulting in shortening the service life of the wire and cable, and in severe cases, the wire and cable will be broken down, and the insulation (sheath) layer will not be lifted. Normal protection function, resulting in electrical short circuit and fire.
3. Wire and cable with qualified tensile strength and elongation of sheathed insulation before aging: unqualified tensile strength and elongation of insulating sheath before aging directly greatly shorten the working life of wire and cable, and During construction or in a long-time electrified environment with high temperature, it is very easy to break the insulator, which will expose the live conductor and cause an electric shock short circuit. The main reason for its disqualification is the use of recycled materials to reduce product costs, and the second is small enterprises that are not qualified for production.
4. Wires with unqualified conductor resistance: Conductor resistance is mainly an important indicator for assessing whether the acsr conductor material and cross-section of the wire and cable meet. When the conductor resistance exceeds the standard, the loss when the current passes through the line is increased, and the heating of the wire and cable is aggravated. The main reason for the unqualified conductor resistance is to reduce the cost of the copper material, which accounts for 80% of the raw material cost. In order to reduce the cost, either reduce the cross-sectional area of the conductor or use recycled copper with excessive impurities, which causes serious conductor resistance of the wire and cable. Exceeding the standard, in addition to easy to cause fire during use, it will also accelerate the aging of the insulating layer covering the wire.