Supervision of the Rotor Bars Breakage Evolution through the Output - - PowerPoint PPT Presentation

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Supervision of the Rotor Bars Breakage Evolution through the Output Voltage of Coil Sensors Placed Outside Induction Motors

POLITEHNICA University of Bucharest EPM_NM Laboratory Virgiliu FIRETEANU Alexandru-Ionel CONSTANTIN

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Contents

• 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
• peration
• Conclusions

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2D Finite element model

Electromagnetic field model Computation domain Electric circuit model Induction motor data

• 7.5 kW
• 3000 rpm
• 3 x 400 V

, 50 Hz

• aluminium squirrel-cage

Ox1 coil Ox coil Uox Uox1 Uox_ox1 Squirrel cage Phase U Phase V Phase W

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Fault analysis for rated load motor

• peration

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 Ωm

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Fault analysis for rated load motor

• peration

Harmonics of phase current IU Time variation of phase currents in healthy motor, HE

Rms values of phase currents for healthy motor: IU = 10.25 A IV = 10.25 A IW = 10.25 A Rms values of phase currents for faulty motor: IU = 9.777 A IV = 9.766 A IW = 9.786 A

Powerpoint Templates Time variation and harmonics of the electromagnetic torque

Mean values: MHE = 31.35 Nm MFA = 29.94 Nm

Fault analysis for rated load motor

• peration

Healthy motor, HE Faulty motor, FA

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Fault analysis for rated load motor

• peration

Time variation and harmonics of the electromagnetic force acting on the rotor -

Mean values: ForceHE = 0.075 N and ForceFA = 277.7 N

faulty motor, FA

Powerpoint Templates Map and lines of the magnetic field outside the motor

Fault analysis for rated load motor

• peration

Healthy motor, HE

Powerpoint Templates Time dependence and harmonics of the magnetic flux density in the centre point of Ox coil

Fault analysis for rated load motor

• peration

Radial component Bx

• f the magnetic flux density

Azimuthal component By

• f the magnetic flux density

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Fault analysis for rated load motor

• peration

Uox_ox1 time dependence, healthy motor (a) and faulty motor (b)

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Fault analysis for rated load motor

• peration

Time dependence and harmonics of the Uox_ox1 voltage

Rms values: Uox_ox1HE = 2.513 mV Uox_ox1FA = 1130 mV Healthy motor, HE Faulty motor, FA

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Evolution of the rotor bar breakage, rated load operation

• 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 Ωm

• Faulty motor, FA2,

with one broken bar - resistivity 1.2x0.48e-7 Ωm

• Faulty motor, FA3,

with one broken bar - resistivity 1.5x0.48e-7 Ωm

• Faulty motor, FA,

with one broken bar - resistivity 0.48 Ωm Rms values of Uox_ox1 voltage and rms faulty/rms healthy Evolution of the Uox_ox1 rms voltage during breakage. Early detection of the bar breakage. HE FA1 FA2 FA3 FA rms Uox_ox1 [mV] 2.513 48.16 171.9 371.4 1130 FA/HE

• 19.16

68.40 147.8 449.7

Powerpoint Templates Uox_ox1 harmonics during FA1-FA2-FA3 bar breakage evolution

Evolution of the rotor bar breakage, rated load operation

Powerpoint Templates Amplitudes of Uox_ox1 harmonics and the values of efficiency, FA?/HE

Evolution of the rotor bar breakage, rated load operation

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 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 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 FA2 FAULTY STATE, 20 % INCREASE OF BAR RESISTIVITY FA3 FAULTY STATE, 50 % INCREASE OF BAR RESISTIVITY FA FAULTY STATE, BROKEN BAR

Powerpoint Templates Amplitudes of Uox_ox1 harmonics and the values of efficiency, FA?/FA1

Evolution of the rotor bar breakage, rated load operation

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 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 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 FA2 FAULTY STATE, 20 % INCREASE OF BAR RESISTIVITY FA3 FAULTY STATE, 50 % INCREASE OF BAR RESISTIVITY FA FAULTY STATE, BROKEN BAR

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Breakage bars supervision for no-load motor operation

Time dependence and harmonics of the Uox_ox1 voltage

Healthy motor, HE Faulty motor, FA Rms values: Uox_ox1HE = 1.231 mV Uox_ox1FA = 130.1 mV

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Breakage bars supervision for no-load motor operation

Rms values: Uox_ox1HE = 1.231 mV Uox_ox1FA = 130.1 mV 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 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 Rms values: Uox_ox1HE = 2.513 mV Uox_ox1FA = 1130 mV RATED LOAD MOTOR OPERATION NO-LOAD MOTOR OPERATION RATED LOAD MOTOR OPERATION NO-LOAD MOTOR OPERATION

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• The supervision of the rotor bars breakage, respectively

the early detection of the broken bars fault in the squirrel-cage induction motors through the

• utput

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.

Conclusions

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THANK YOU