SLIDE 1 Analysis of the Evolution of the Stator Short-circuit and Rotor Bar Breakage Faults in a Squirrel- cage Induction Motor
- V. FIRETEANU and A. I. CONSTANTIN – POLITEHNICA University of Bucharest
Vincent LECONTE and Patrick LOMBARD – ALTAIR Engineering France
SLIDE 2 Summary
Introduction
Dedicated finite element model of a squirrel-cage induction motor
Stator short-circuit fault signatures. Early detection of the short-circuit fault
Rotor bar breakage signatures.
Early detection of the bar breakage through harmonics of the stator currents and of the magnetic field
Conclusions
SLIDE 3 3D finite element model of a squirrel-cage IM. Rotor bar breakage simulation
7.5 kW two-poles squirrel-cage IM 3 x 380 V, 50 Hz supplied Healthy motor: resistivity of all rotor bars, ρ = 0.048 Ωmm2/m Bar breakage simulation: increased resistivity 1.2ρ, 2ρ, 10ρ, 102ρ, 103ρ, 107ρ , for FAR1, FAR2, FAR3, FAR4, FAR5, FAR6
Rotor speed = 2880 rpm
SLIDE 4 Stator short-circuit fault simulation
Rshc
Coils of the phase U of stator winding. Elementary coil subject of the short- circuit fault, in yellow Circuit model associated to the 3D finite element model of an IM Healthy motor: Rshc = 10 MΩ Short-circuit simulation: Rshc = 90 Ω, 9.0 Ω, 5.0 Ω, 0.9 Ω, for FAS1, FAS2, FAS3, FAS4
Rotor speed = 3000 rpm
SLIDE 5 Stator short-circuit fault signatures
(1) Signature in the stator phase U current Healthy motor FAS4 faulty state
SLIDE 6 Stator short-circuit fault signatures
(2-1) Signature in the magnetic field Bx[M] outside the motor Healthy motor FAS4 faulty state
SLIDE 7 Stator short-circuit fault signatures
(2-2) Signature in the magnetic field Bz[P] + Bz[Q] outside the motor Healthy motor FAS4 faulty state
SLIDE 8 Broken rotor bar fault signatures
(1) Signature in the stator phase U current Healthy motor FAR6 faulty state
SLIDE 9 Broken rotor bar fault signatures
(2) Signature in the magnetic field Bz[P] + Bz[Q] outside the motor Healthy motor FAR6 faulty state
SLIDE 10 Early detection of the stator short-circuit and a rotor bar breakage faults
EFFICIENCY of FAULT DETECTION criterion definition : ratio between the amplitude of a given harmonic for faulty state and for healthy state Fault detection through the harmonics of the stator currents Fault detection through the harmonics of local values of different components of the magnetic flux density outside the motor
SLIDE 11 Early detection
stator short-circuit fault
SLIDE 12
f [Hz] FAS1 FAS2 FAS3 FAS4 150 1.055 1.821 2.340 4.320 950 0.976 0.985 1.053 1.596 1050 0.723 4.675 8.113 27.74
Efficiency of the short-circuit detection through harmonics of the IU stator current
SLIDE 13
Efficiency of the short-circuit detection through harmonics of the IU stator current
SLIDE 14
f [Hz] FAS1 FAS2 FAS3 FAS4 950 1.009 1.081 1.194 2.466 1050 1.013 1.117 1.217 1.800
Efficiency of the short-circuit detection through harmonics of Bx[M]
SLIDE 15
Efficiency of the short-circuit detection through harmonics of Bx[M]
SLIDE 16
f [Hz] FAS1 FAS2 FAS3 FAS4 750 1.026 1.173 1.331 3.023 1350 1.015 1.249 1.608 6.524 1950 1.016 1.298 1.766 3.777
Efficiency of the short-circuit detection through harmonics of Bx[M] – Bx[N]
SLIDE 17
Efficiency of the short-circuit detection through harmonics of Bx[M] – Bx[N]
SLIDE 18
f [Hz] FAS1 FAS2 FAS3 FAS4 1250 1.320 4.471 6.235 20.32 1950 1.042 3.660 11.37 41.76
Efficiency of the short-circuit detection through harmonics of Bz[P] + Bz[Q]
SLIDE 19
Efficiency of the short-circuit detection through harmonics of Bz[P] + Bz[Q]
SLIDE 20 Most appropriate quantity & harmonic to supervise the stator short-circuit fault evolution
Bz[P] + Bz[Q] Bx[M] Bx[M] – Bx[N] IU current
SLIDE 21 Early detection
rotor bar breakage fault
SLIDE 22
f [Hz] FAR1 FAR2 FAR3 FAR6 46 3.27 8.29 14.09 34.52 225 1.056 1.174 1.673 3.478
Efficiency of the rotor bar breakage detection through harmonics of the IU stator current
SLIDE 23
Efficiency of the rotor bar breakage detection through harmonics of the IU stator current
SLIDE 24 Efficiency of the rotor bar breakage detection through harmonics of Bx[M]
f [Hz] FAR1 FAR2 FAR3 FAR4 FAR5 FAR6 2 1.145 1.438 4.542 21.17 68.92 115.6
2 Hz is the frequency of rotor currents corresponding to the motor speed 2880 rpm
SLIDE 25
Efficiency of the rotor bar breakage detection through harmonics of Bx[M]
SLIDE 26 Efficiency of the rotor bar breakage detection through harmonics of Bx[M]-Bx[N]
f [Hz] FAR1 FAR2 FAR3 FAR4 FAR5 FAR6 2 4.657 15.72 52.96 268.2 890.7 1513 100 1.285 4.250
SLIDE 27
Efficiency of the rotor bar breakage detection through harmonics of Bx[M]-Bx[N]
SLIDE 28
Efficiency of the rotor bar breakage detection through harmonics of Bx[P]-Bx[Q]
f [Hz] FAR1 FAR2 FAR4 FAR6 100 1.285 3.266 7.640 33.00
SLIDE 29
Efficiency of the rotor bar breakage detection through harmonics of Bx[P]-Bx[Q]
SLIDE 30 Efficiency of the rotor bar breakage detection through harmonics of Bz[P]
f [Hz] FAR1 FAR2 FAR3 FAR4 FAR5 FAR6 2 1.361 2.627 9.128 44.14 144.9 244.6 100 1.057 1.587
SLIDE 31
Efficiency of the rotor bar breakage detection through harmonics of Bz[P]
SLIDE 32 Efficiency of the rotor bar breakage detection through harmonics of Bz[P] +Bz[Q]
f [Hz] FAR1 FAR2 FAR3 FAR4 FAR5 FAR6 2 6.557 21.76 74.11 369.6 1225 2073 100 1.532 4.912
SLIDE 33
Efficiency of the rotor bar breakage detection through harmonics of Bz[P] +Bz[Q]
SLIDE 34 Most appropriate quantity & harmonic to supervise the rotor bar breakage evolution
Bz[P] + Bz[Q] Bx[M] Bx[M] – Bx[N] IU current Bz[P] Bx[P] – Bx[Q]
SLIDE 35 Conclusions
The monitoring of the evolution of the short-circuit faults in the IM stator winding through the stator currents and/or the magnetic field in the motor proximity represent an efficient solution. The harmonic 1050 Hz of the stator current offer high values of the efficiency in early detection of the stator short-circuit fault. The short-circuit fault investigation based on the axial component of the magnetic field in the overhang region of the stator winding offers the best result with the 1250 Hz harmonic. The monitoring of the broken bar faults can be done through the following harmonics of the stator current and of the magnetic field: a) the 46 Hz harmonic of the current, with the efficiency of fault detection 35; b) the 225 Hz harmonic of the current, with the efficiency of fault detection 4; c) the 2 Hz harmonic of the magnetic field Bz[P] + Bz[Q], with a very high efficiency of fault detection 2100; d) the 100 Hz harmonic of the magnetic field Bz[P] + Bz[Q], with the efficiency 54.
SLIDE 36
THANKS
