Powerpoint Templates Supervision of the Rotor Bars Breakage Evolution through the Output Voltage of Coil Sensors Placed Outside Induction Motors Virgiliu FIRETEANU Alexandru-Ionel CONSTANTIN POLITEHNICA University of Bucharest EPM_NM Laboratory Powerpoint Templates
Contents Powerpoint Templates • 2D Finite element model • Fault analysis for rated load motor operation • Supervision on the evolution of the rotor bar breakage for rated load motor operation • Breakage bars supervision for no-load motor operation • Conclusions
2D Finite element model Powerpoint Templates Electromagnetic field model Computation domain Electric circuit model Uox Phase U Uox_ox1 Phase V Ox1 Ox Uox1 coil coil Phase W Squirrel cage Induction motor data • 7.5 kW • 3000 rpm • 3 x 400 V , 50 Hz • aluminium squirrel-cage
Fault analysis for rated load motor Powerpoint Templates operation Models analyzed - Healthy motor, HE, with the resistivity of all bars 0.48e-7 Ωm - Faulty motor, FA, with one broken bar - resistivity 0.48 Ω m
Fault analysis for rated load motor Powerpoint Templates operation Time variation of phase currents in healthy motor, HE Rms values of phase currents for healthy motor: I U = 10.25 A I V = 10.25 A I W = 10.25 A Harmonics of phase current I U Rms values of phase currents for faulty motor: I U = 9.777 A I V = 9.766 A I W = 9.786 A
Fault analysis for rated load motor Powerpoint Templates operation Time variation and harmonics of the electromagnetic torque Healthy motor, HE Faulty motor, FA Mean values: M HE = 31.35 Nm M FA = 29.94 Nm
Fault analysis for rated load motor Powerpoint Templates operation Time variation and harmonics of the electromagnetic force acting on the rotor - faulty motor, FA Mean values: Force HE = 0.075 N and Force FA = 277.7 N
Fault analysis for rated load motor Powerpoint Templates operation Map and lines of the magnetic field outside the motor Healthy motor, HE
Fault analysis for rated load motor Powerpoint Templates operation Time dependence and harmonics of the magnetic flux density in the centre point of Ox coil Azimuthal component By Radial component Bx of the magnetic flux density of the magnetic flux density
Fault analysis for rated load motor Powerpoint Templates operation Uox_ox1 time dependence, healthy motor (a) and faulty motor (b)
Fault analysis for rated load motor Powerpoint Templates operation Time dependence and harmonics of the Uox_ox1 voltage Healthy motor, HE Faulty motor, FA Rms values: Uox_ox1 HE = 2.513 mV Uox_ox1 FA = 1130 mV
Evolution of the rotor bar breakage, rated Powerpoint Templates load operation Evolution of the Uox_ox1 rms voltage during breakage. Early detection of the bar breakage. - Healthy motor, HE, with the resistivity of all bars 0.48e-7 Ωm - Faulty motor, FA1, with one broken bar - resistivity 1.05x0.48e-7 Ω m - Faulty motor, FA2, with one broken bar - resistivity 1.2x0.48e-7 Ω m - Faulty motor, FA3, with one broken bar - resistivity 1.5x0.48e-7 Ω m - Faulty motor, FA, with one broken bar - resistivity 0.48 Ω m Rms values of Uox_ox1 voltage and rms faulty/rms healthy HE FA1 FA2 FA3 FA rms Uox_ox1 [mV] 1130 2.513 48.16 171.9 371.4 FA/HE - 19.16 68.40 147.8 449.7
Evolution of the rotor bar breakage, rated Powerpoint Templates load operation Uox_ox1 harmonics during FA1-FA2-FA3 bar breakage evolution
Evolution of the rotor bar breakage, rated Powerpoint Templates load operation Amplitudes of Uox_ox1 harmonics and the values of efficiency, FA?/HE FA2 FAULTY STATE, 20 % INCREASE OF BAR RESISTIVITY f[Hz] 160 200 260 300 560 FA2 [mV] 11.12 104.0 3.838 40.65 6.621 FA2/HE 29126 31878 49678 56825 27511 FA3 FAULTY STATE, 50 % INCREASE OF BAR RESISTIVITY f[Hz] 160 200 260 300 560 FA3[mV] 22.87 239.3 8.145 84.73 13.31 FA3/HE 59867 73394 105414 118458 55279 FA FAULTY STATE, BROKEN BAR f[Hz] 200 260 300 560 580 FA [mV] 704.1 36.55 231.5 54.95 183.2 FA/HE 215899 473114 323624 228310 249936
Evolution of the rotor bar breakage, rated Powerpoint Templates load operation Amplitudes of Uox_ox1 harmonics and the values of efficiency, FA?/FA1 FA2 FAULTY STATE, 20 % INCREASE OF BAR RESISTIVITY f[Hz] 840 1010 1130 1140 1310 FA2 [mV] 4.707 3.512 1.562 2.796 4.530 FA2/FA1 3.914 4.298 4.417 4.052 4.420 FA3 FAULTY STATE, 50 % INCREASE OF BAR RESISTIVITY f[Hz] 920 1010 1020 1120 1310 FA3[mV] 7.020 9.559 10.36 4.291 9.906 FA3/FA1 10.50 11.70 9.705 11.14 9.663 FA FAULTY STATE, BROKEN BAR f[Hz] 610 820 1120 1130 1170 FA [mV] 26.31 27.44 23.38 30.22 54.79 FA/FA1 114.8 99.19 60.70 85.48 128.9
Breakage bars supervision for no-load Powerpoint Templates motor operation Time dependence and harmonics of the Uox_ox1 voltage Healthy motor, HE Faulty motor, FA Rms values: Uox_ox1 HE = 1.231 mV Uox_ox1 FA = 130.1 mV
Breakage bars supervision for no-load Powerpoint Templates motor operation RATED LOAD MOTOR OPERATION NO-LOAD MOTOR OPERATION Rms values: Rms values: Uox_ox1 HE = 2.513 mV Uox_ox1 HE = 1.231 mV Uox_ox1 FA = 1130 mV Uox_ox1 FA = 130.1 mV RATED LOAD MOTOR OPERATION f[Hz] 200 260 300 560 580 FA [mV] 704.1 36.55 231.5 54.95 183.2 FA/HE 215899 473114 323624 228310 249936 NO-LOAD MOTOR OPERATION f[Hz] 500 600 1100 1200 1500 FA [mV] 45.67 39.92 37.60 23.44 18.55 FA/HE 4654 5986 20779 7120 6977
Conclusions Powerpoint Templates • The supervision of the rotor bars breakage, respectively the early detection of the broken bars fault in the squirrel-cage induction motors through the output voltage of a system that consist in two identical series connected coils, is proved to be a very efficient method. • The rms value of the system output voltage and the amplitude of particular harmonics of this voltage are very sensitive to the change of the resistance of bars. • The efficiency of the rotor bar breakage supervision is much more important for rated-load motor operation than for no-load operation.
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