Medium voltage cables refer to power cables with a rated voltage between 6kV and 35kV,typically used to transmit medium voltage electricity.Medium voltage cables typically consist of one or more copper or aluminum conductors,insulation layers,sheaths,and other accessories.The conductors of medium voltage cables are usually made of copper or aluminum because these materials have good conductivity and mechanical strength.The insulation layer usually uses materials such as polyethylene,cross-linked polyethylene,rubber,etc.to ensure the insulation performance of the cable.The sheath can protect the cable from mechanical damage and environmental impact.The importance of medium voltage cables in the power system is self-evident.
　　1.Classification of medium voltage cables
　　Medium voltage cables can be classified according to different standards and purposes.The following are some common classification methods:
　　According to the classification of conductor materials:The conductors of medium voltage cables are usually made of copper or aluminum,so they can be divided into copper conductor medium voltage cables and aluminum conductor medium voltage cables.
　　According to the classification of insulation materials,the insulation layer of medium voltage cables is usually made of materials such as polyethylene,cross-linked polyethylene,rubber,etc.Therefore,it can be divided into polyethylene insulated medium voltage cables,cross-linked polyethylene insulated medium voltage cables,and rubber insulated medium voltage cables.
　　According to structural classification,medium voltage cables can be divided into single core medium voltage cables and multi-core medium voltage cables.Single core medium voltage cables have only one conductor and are suitable for transmitting single-phase electricity;Multi core medium voltage cables have multiple conductors and are suitable for transmitting three-phase electricity.
　　Classification based on usage:Medium voltage cables can be classified according to different uses,such as urban power grid medium voltage cables,industrial medium voltage cables,mining medium voltage cables,petrochemical medium voltage cables,etc.
　　2.Performance of medium voltage cables
　　The performance of medium voltage cables includes two aspects:electrical performance and mechanical performance.The electrical performance mainly refers to the resistance,capacitance,insulation resistance,dielectric loss,discharge characteristics and other indicators of the cable.The mechanical properties mainly include the tensile strength,pressure resistance,wear resistance,tensile and bending resistance,temperature resistance,and other indicators of the cable.
　　3.Application scope of medium voltage cables
　　The application fields of medium voltage cables are very extensive,covering many fields such as urban distribution,rural power grids,mining power systems,and rail transit systems.With the development needs of the country,the application fields of medium voltage cables are becoming increasingly widespread.
　　4.Quality control of medium voltage cables
　　The quality of medium voltage cables is directly related to the normal operation and electricity safety of the power system.Quality control of medium voltage cables is crucial in the production process.Production enterprises establish strict quality control standards,use high-quality raw materials,strengthen production supervision,ensure product quality,and avoid unstable power signals causing problems in the power system.