Influence Factor Of Testing Precise For Premium Efficiency Motors

In the energy efficiency test of high efficiency motor,how to find out the factors that affect the accuracy of the motor test and analyze their influencing level,so as to put forward the improvements,is the key problem to improve the testing precision of motor efficiency.Based on the analysis of national test standards,this thesis puts forward three influence factors,including circulation of the delta-connection,installation precision of the couplings and uncertainty of the test.Experiments for each influence factor are designed and the influence laws are obtained through a large number of measured data.The main contents are as follows:1)Considering the saturation effect,the mechanism of circulation in induction motors with delta-connection is explained through theoretical study and time-stepping finite element method.The effect of circulation on the energy efficiency determination of induction motors is analyzed.Then the different delta-connected motors with the capacity from 4kW to 55 kW are tested and analyzed,and the influence laws of circulation on the energy efficiency determination are obtained.The improvement measures of energy efficiency test are put forward to avoid the influence of circulation.2)Through the analysis of the misalignment of couplings,the energy efficiency tests on the ball coupling and rigid connection coupling are designed under different installation accuracy.According to the existing standards and methods,the motor efficiency can be tested and calculated.Through analysis of the test results,the influencing level of the installation accuracy of the couplings on the motor efficiency test can be obtained,and then reasonable suggestions are put forward.3)Taking a 7.5kW motor as an example,guide to the expression of uncertainty in measurement(GUM)and Monte Carlo method are used to evaluate the uncertainty of the motor efficiency.The specific value of the uncertainty is obtained under standard test method.Comparing the difference between the GUM method and the Monte Carlo method in the evaluation of the uncertainty of the induction motor energy efficiency test,the influence of uncertainty of motors on the determination of energy efficiency is obtained.