| There are many kinds of installation methods for XLPE insulated cable intermediate joint,such as prefabricated,cold shrinkable,heat shrinkable and so on.The connection process of copper cable conductor usually adopts copper tube crimping,and uses stress tube and stress cone to overcome the influence of distorted electric field.However,the traditional crimping process is mainly controlled by the operator,so a little carelessness will easily lead to the occurrence of heating,insulation damp,local electric field distortion and other conditions of the core crimping part of the intermediate connector,which will eventually lead to the breakdown of the connector,seriously affecting the reliability of power supply and the safety and stability of transmission and distribution lines.At present,the latest "cable fusion joint technology" has some problems,such as complex process of making cable middle head,high temperature of core fusion,long time consuming and high price.In this paper,in order to solve the problems caused by the cable joint,firstly,according to the existing materials and micro alloying methods,the electrical connection materials suitable for 10 kV cable joint are selected.Secondly,the COMSOL finite element simulation software is used to simulate the new connection mold and the design of the connecting mode is carried out according to the simulation results.Finally,the connection of 10 kV cable intermediate joint is realized by connecting mode and electrical connection material,and the current carrying temperature rise,contact resistance and tensile force are tested to verify the feasibility of use.The main features and innovative results of this paper are as follows:1.Through the preparation of the binary alloy,the thermal,electrical,mechanical and interface properties of Sn-1.5Cu and Sn-58 Bi are obtained,the melting point of the binary alloy is 232.4 ℃ and 145.4 ℃;the conductivity is 2.841×106s M and1.445×106s/m respectively;the tensile strength is 22.54 MPa and 55.97 MPa respectively;the spreading area is 57.2mm2 and 132.5mm2 respectively.2.According to the index parameters of 10 kV cable intermediate joint,the parameters with insufficient performance are modified.By adding different contents of Zn,In,Bi and Cu,the performance is different.Among them,Sn-1.5Cu with In element increase and Sn-19.4Bi with Bi element reduction have the best effect,but the addition content is different,for Sn-1.5Cu alloy,5% In element needs to be added,and for Sn-19.4 Bi alloy needs to add 2% In element.3.Based on the COMSOL finite element simulation software,the temperature simulation of the connection mold of the cable joint is carring out.The aluminum heating plate type cable intermediate joint mold should be used as the heating equipment.When the heating time is 350 s,the connection temperature of the mold is239.79 ℃,the temperature of the insulation layer is 90.235 ℃,and the length of the cable stripped at both ends of the cable is 18 cm at this time,which is the best scheme.4.Four different ternary alloy materials were used as electrical connection materials to compare with the existing crimping joints.The properties of joints made of electrical connection materials are better than those of traditional joints,among them,Sn-19.4Bi-2In is the best one as the cable intermediate joint of electrical connection material,in the temperature rise current carrying test,the temperature of the intermediate joint reaches 80.6 ℃,which is 11.7 ℃ lower than that of the cable conductor,the contact resistance is 10.23 μΩ,which is 151.12% lower than that of traditional crimping joint;the maximum tensile force of the 10 kV cable intermediate joint is 8676.354 n,which meets and surpasses the maximum tensile force required by the 10 kV cable intermediate joint,at the same time,it accords with the corresponding tensile strength value of electrical connection materia.Sn-19.4bi-2In is used as electrical connection material,which is feasible to use it in the middle joint of cable,and it has good performance and meets all requirements. |
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