Study On The Influence And Treatment Of Three-phase Unbalance Of Large Air Conditioning Engine On Cable Bridge At Its Access Port

Large air conditioning centrifugal units have the characteristics of high efficiency,flexible operation and convenient operation,which are widely used in all kinds of industrial and civil projects.Problems such as cable bridge heating,fire,low-frequency vibration and noise caused by three-phase imbalance of engine in the process of air conditioning operation are becoming increasingly prominent.This paper conducts in-depth research and analysis on such problems.The grid modeling method of ANSYS Maxwell and Workbench electromagnetic simulation software was discussed.According to the multi-field coupling simulation theory,the multi-field coupling simulation flow chart of cable bridge eddy current effect modeling caused by three-phase unbalance of air conditioner was designed,and the multi-field coupling relationship between electromagnetic field and eddy current thermal effect and mechanical effect was analyzed.For air conditioning host unbalanced three-phase cable bridge caused by fever,low frequency vibration and noise problem,based on the principle of electromagnetic eddy current heating effect and mechanical effect,using the Maxwell’s electromagnetic simulation software,was founded by the method of multi field coupling cable bridge 3 d model,including cable bridge geometry model,the temperature field model,structure model and noise field model,The influence and coupling relation among physical fields are analyzed.The model is used to simulate the influence of eddy current effect on the heating,vibration and noise of cable bridge when the three-phase current is unbalanced.The simulation results show that reducing the unbalance degree of three-phase cable,normalizing the arrangement of three-phase cable and cutting off the magnetic circuit of closed ferromagnetic cable bridge are effective to solve the above problems.For air conditioning host unbalanced three-phase cause the problem of cable bridge fire,according to the actual parameters of air conditioning host,the two-dimensional model is established,under the unbalanced input different degrees of input current incentive model,model simulation respectively,it is concluded that different input unbalanced three phase current and output the laws between the motor shell induced current parameters.According to the theoretical analysis and simulation results,the fault management measures caused by three-phase unbalance of large air conditioning engine are improved,including standard preventing of three-phase single-core cable according to the loop,replacing the iron cover plate of cable bridge with plastic cover plate,supplementing the grounding of host and cable bridge,etc.The parameters such as current,temperature and noise value of cable bridge before and after rectification are measured,and the measured data before and after rectification are compared and analyzed,which shows the effectiveness of the simulation results.After a long period of operation,the fault disappears or is significantly improved,and the treatment method is effective.This study improves the reliability,stability and safety of the operation of air conditioning units,and provides reference for the prevention of such electrical faults.