Three phase induction motors are complex electro-mechanical devices widely used in most industrial applications. Induction motors are susceptible to many types of fault in industrial application such as rotor bar broken fault, stator inter turn fault, eccentricity fault. Out of these faults eccentricity is very specific in squirrel cage induction motor. If the initial stage of motor failure is not identified will cause the severe damage and production shutdowns. This paper presents the simulations of eccentricity fault detection in three phase squirrel cage induction motor under various load conditions for healthy and faulty conditions. In this paper, dynamic model of induction motor is developed using CAD package called MagNet for static and transient 2D analysis. The various machine parameters like stator current, magnetic flux density, and magnetic torque are calculated and their values are compared under healthy and faulty conditions.

1. DETECTION AND ANALYSIS OF ECCENTRICITY
FAULTS IN 3Φ SQUIRREL CAGE INDUCTION MOTOR
USING MAGNET V7.11
Ramkumar.B
Research scholar
Ramkumar.b131@gmail.com
+919566853974
Nagarajan S.
Professor
Nagu.shola@yahoo.com
+919444177170
Department of Electrical and Electronics Engineering, Jerusalem College of Engineering, Chennai, India
Abstract—Three phase induction motors are complex
electro-mechanical devices widely used in most industrial
applications. Induction motors are susceptible to many
types of fault in industrial application such as rotor bar
broken fault, stator inter turn fault, eccentricity fault. Out
of these faults eccentricity is very specific in squirrel cage
induction motor. If the initial stage of motor failure is not
identified will cause the severe damage and production
shutdowns. This paper presents the simulations of
eccentricity fault detection in three phase squirrel cage
induction motor under various load conditions for healthy
and faulty conditions. In this paper, dynamic model of
induction motor is developed using CAD package called
MagNet for static and transient 2D analysis. The various
machine parameters like stator current, magnetic flux
density, and magnetic torque are calculated and their
values are compared under healthy and faulty conditions.
Keywords—Induction motor, Eccentricity, Static 2D
analysis, Flux density, Stator current, MagneticTorque.
1. Introduction
Induction motors are frequently used in industrial
applications in a wide range of operating areas,
because of its to simple and robust structure, and low
production costs. Fault diagnosis systems are used as
a system for maintenance and protection of the
expensive systems against faults. These systems
predict performance by receiving the required
information from the system or process. When the
rotor, stator and rotational axes of a motor are not
coincide, the air gap becomes non-uniform.
Approximately 80% of the mechanical faults lead to
the stator and rotor eccentricity. Of course, this
eccentricity may occur during the process of
manufacturing and fixing the rotor. There are two
kinds of eccentricity is occur namely it as static and
dynamic eccentricity. When the static eccentricity
occurs, the rotor rotational axe is coincide with its
symmetry axe, but has displacement with the stator
symmetrical axe. In this case, the air gap around the
rotor is uniformity, but it is invariant with time. In
the case of broken rotor bars in the presence of the
intrinsic static eccentricity, the instantaneous
presence of two faults must be considered.
Meanwhile, rotor bars breakage causes the static
eccentricity and it is possible that two faults occur
simultaneously. Due to mis-alignment of rotor axis
during installation of rotor in the induction motor the
airgap will become uneven. Due to eccentricity more
mechanical vibrations will occur, which will reduce
the life span of the machine. Unbalanced magnetic
pull will occur which will lead to rotor and stator rub
which results in winding damage. Hence detection of
such faults is essential for the protection of induction
motors against failures and permanent damages. The
demand for accurate fault detection and diagnosis
methods has increased for complex industrial
systems to be safer and more reliable, while
minimizing the processing time [6]. The
conventional equivalent circuit model is described to
determine the equivalent circuit components for a
three phase squirrel cage induction motor using finite
element model. The method uses separate finite
element models for rotor and stator. The prediction
of eccentricity level in the faulty motor is determined

2. using finite element method. The stator current is
measured using on-line current monitoring method.
Frequency component analysis is done to predict the
amplitude of current and fifth and seventh harmonics
are excluded [14]. Commercial finite element
packages are described how to simulate rotor faults
and hence enhance the capability of practical
condition monitoring schemes. Accurate models of
the machine under faulted conditions are developed
using both fixed mesh and time-stepping finite
element packages [7]. The modelling and analysis of
induction motor is done using winding function
method and finite element method. Harmonics
analysis is done for stator current and compared the
results for both healthy and faulty machines. It is
proved that finite element method is the best
approach [4]. An accurate model is presented for
diagnosis of squirrel cage induction motor using
MagNet package. The model is analyzed based on
finite element method and comparison is done for
both the healthy and faulty conditions [9]. A
technique is developed for detection and
categorization of dynamic, static eccentricities and
bar, end-ring connector breakages in squirrel-cage
induction motors using Time- Stepping Coupled
Finite-Element–State-Space method to generate fault
case performance data, which contain phase current
waveforms and time-domain torque profiles [6]. The
detection and analysis of broken bar fault is done in
three phase squirrel cage induction motor using
MagNet cad package. The static analysis and
transient analysis is done for both healthy and faulty
motor based on finite element method and the
readings are tabulated An new offline method is
projected to detect the eccentricity fault by analyzing
the impedance spectrum due to zigzag path of
leakage flux in induction motor. This is already used
for broken bar detection method [2]. 3D analysis is
done using finite element method just for normal
operation, not in faulty condition [8]. The above
papers use MCSA, Thermal Monitoring, Vibration
Monitoring, etc for the purpose of fault detection and
modelling. But in this paper to detect the eccentricity
fault in the three phase induction motor “Finite
Element Method” is adopted to perform both Static
and Transient 2D analysis for healthy and faulty
conditions. The analysis is carried out with a CAD
package called MagNet.
 The magnetic field outside the motor
periphery is negligible.
 Hysteresis effects are neglected.
 The magnetic field distribution is constant
along the axial direction of the motor.
 The displacement currents are neglected.
2. Induction machine data
Rated Power - 22 kW or 30HP
Rated Voltage - 415 V
Stator Current - 38.20 A
Rated Frequency - 50Hz
Rated Speed - 1475 rpm
Number of Poles - 4
Number of Stator Slots - 36
Number of Rotor Slots - 24
Efficiency - 92.8%
Power Factor - 0.86
3. Induction motor model
Figure1.shows the model of induction motor
developed using the cad package MagNet. This
model is based on closed boundary conditions with
the calculated diameter and length. Shaft is made up
of S430 grade stainless steel material and both the
rotor and stator are made up of silicon steel. The
number of coil windings and the turns are designed
based on the calculations and they are made up of
copper material.
Figure 1. Induction motor model
4. Static analysis
In this section, the simulation results for the Static
Analysis of Three Phase Induction Motor for the case
of healthy motor, faulty motor with 10% eccentricity
under no load, half load and full load are presented
A. Distribution of magnetic field and flux
The distribution of flux function and flux density
is symmetrical in case of healthy condition, while the
magnetic field distribution is unsymmetrical in the
case of eccentricity fault. Field and flux distribution
is evaluated with respect to the circumference which
is calculated as distance in millimeter.

3. (a)
(b)
(c)
(d)
Fig 2. Magnetic field distribution under full load (a)
Healthy (b) 10% eccentricity
Magnetic flux distribution under full load (c)
Healthy (d) 10% eccentricity
Field and flux distribution plots for the case of
healthy and faulty motor, for full load condition with
10% eccentricity shown in figure 2. It can be
observed that plots appear to drastically change its
symmetry when the eccentricity level increases.
Table 1. Summary of Flux Function
Condition Flux Function(wb)
Simulated
value
Theoretical
Value
No load Healthy 0.0006 0.000598
10%Eccentricity 0.00067 -
Half
load
Healthy 0.00334 0.00299
10%Eccentricity 0.00562 -
Full
load
Healthy 0.00599 0.00598
10%Eccentricity 0.00789 -
From the table 1 it is observed that under no load
condition flux function has been increased when the
percentage of eccentricity increases, Similarly values
for half load and full load are tabulated and the
values are plotted in graph.
Table 2. Summary of Flux Density
Condition
Flux
Density(wb/m2
)
Simulated
value
Theoretical
Value
No load Healthy 0.044 0.045
10%Eccentricity 0.0497 -
Half
load
Healthy 0.227 0.225
10%Eccentricity 0.46 -
Full
load
Healthy 0.44 0.45
10%Eccentricity 0.647 -
From the table 2 it is observed that under no load
condition, the flux density has been increased when
the percentage of eccentricity increases, Similarly
values for half load and full load are tabulated and
the values are plotted in graph
Fig 3. Graphical Representation of Flux Function and Flux
Density
5. Validation for Static analysis
Both simulated and theoretical values for flux
function and flux density for healthy condition is
given in Table.
HEALTHY
CONDITION
SIMULATED
VALUE
THEORETICAL
VALUE
Flux function 0.00599 Wb 0.00598 Wb
Flux density 0.44 Wb/m2
0.45 Wb/m2
From the tabulation it is observed that the simulated
values of flux function and flux density are correlated
with the theoretically calculated values

4. 6. Transient analysis
The performance of the motor during transient
periods is difficult to analyze under real time
operating conditions. The transient analysis is
performed for healthy conditions and various faulty
conditions under various loads and the following
parameters like current, flux, torque are to be
compared.
7. Transient model of Induction Motor
The circuit model of the three phase induction
motor is shown in Figure 4. The power source is
considered as a voltage source connected with the
series resistances and inductances of the stator
windings in each phase. The rotor circuit model is
made of short-circuited bar conductors. The voltage
relations for all the phases are defined as,
𝑉1 = 𝑉𝑚 sin wt (1)
𝑉2 = 𝑉𝑚 sin (wt-2π/3) (2)
𝑉3 = 𝑉𝑚 sin (wt+2π/3) (3)
Fig 4. Circuit Diagram of Induction Motor
A. Stator Current
The stator phase current plot for healthy and
faulty motor under full load condition is shown in
Figure 5. The time step is taken as 1ms. It is
observed that stator phase current waveform gets
disturbed when the percentage of eccentricity
increases.
(a) (d)
(b) (e)
(c) (f)
Fig 5. Stator Phase Current Plot under full load condition
(a) Healthy (b) 10% eccentricity (c) 20% eccentricity
under static eccentricity
(d) Healthy (e) 10% eccentricity (f) 20% eccentricity
under dynamic eccentricity
Table 3. Summary of Stator Current
Condition Stator
Current(A)
Static
Eccentricity
Dynamic
Eccentricity
No
load
Healthy 4 4
10%Eccentricity 5.5563 6.171
20%Eccentricity 6.744 7.02
Half
load
Healthy 19 19
10%Eccentricity 19.047 20.665
20%Eccentricity 21.373 22.77
Full
load
Healthy 39 39
10%Eccentricity 40.301 41.86
20%Eccentricity 42.43 46
From Table 3, it is observed that the stator current
increases when the level of eccentricity increases,
i.e., under the healthy motor condition, the current
obtained is 4A. For 10% static eccentricity, the
current obtained is 5.5563A, and percentage change
is 12.6%, for 20% eccentricity, the current obtained
is 6.744A, and the percentage change is 17.8%, for
10% dynamic eccentricity, the current obtained is
6.171A, and the percentage change is 33.5%, for
20% eccentricity, the current obtained is 7.02A, and
the percentage change is 36.1% for no load. Hence
this observation shows an increase in the percentage
change. Similar values are tabulated for half and full
load condition and the values of various load
conditions are plotted in graph.

5. (a) (b)
Fig 6. Graphical Representation of Stator Phase Current
under various load conditions (a) Static analysis (b)
Dynamic Analysis
From the graph, it is observed that, the stator phase
current is increased when the percentage of
eccentricity increases.
B. Magnetic Flux Linkage
(a) (d)
(b) (e)
(c) (f)
Fig 7. Magnetic Flux Linkage Plot under full load
condition
(a) Healthy (b) 10% eccentricity (c) 20% eccentricity
under static eccentricity
(d) Healthy (e) 10% eccentricity (f) 20% eccentricity
under dynamic eccentricity
The magnetic flux linkage for healthy and faulty
motor under full load condition is shown in Figure 7.
It is observed that flux linkages gets disturbed and
pulsated when the percentage of eccentricity
increases.
Table 4. Summary of Magnetic Flux Linkage
Condition
Flux Linkage (wb)
Static
Eccentricity
Dynamic
Eccentricity
No
load
Healthy 0.0478 0.0478
10%Eccentricity 0.052 0.092
20%Eccentricity 0.076 0.123
Half
load
Healthy 0.127 0.127
10%Eccentricity 0.136 0.141
20%Eccentricity 0.14 0.179
Full
load
Healthy 0.26 0.26
10%Eccentricity 0.275 0.287
20%Eccentricity 0.301 0.33
From Table 4, it is observed that the magnetic flux
linkage increases when the level of eccentricity
increases, i.e., under the healthy condition, the flux
linkage obtained is 0.0478wb. During static
eccentricity for 10% eccentricity, the flux linkage
obtained is 0.052wb and for 20% eccentricity the
flux linkage obtained is0.076wb. During dynamic
eccentricity for 10% eccentricity, the flux linkage
obtained is 0.092wb and for 20% eccentricity, flux
linkage obtained is 0.123wb for no load. Hence this
observation shows an increase in the percentage
change. Similarly values are tabulated for half and
full load condition.
(a) (b)
Fig 8. Graphical representation of flux linkage under
various load conditions
(a) Static analysis (b) Dynamic analysis
From the graph, it is observed that, the magnetic flux
linkage is increased when the percentage of
eccentricity increases
C. Magnetic Torque
(a) (d)

6. (b) (e)
(c) (f)
Fig 9. Magnetic Torque Plot under full load condition
(a) Healthy (b) 10% eccentricity (c) 20% eccentricity
under static eccentricity
(d) Healthy (e) 10% eccentricity (f) 20% eccentricity
under dynamic eccentricity
The magnetic torque for healthy and faulty motor
under full load condition is shown in Figure 9. It is
observed that torque gets disturbed and pulsated
when the percentage of eccentricity increases.
Table 5. Summary of Magnetic Torque
Condition Torque(N-m)
Static
Eccentricity
Dynamic
Eccentricity
No
load
Healthy 1.24 1.24
10%Eccentricity 2.0685 2.45
20%Eccentricity 2.97 3.061
Half
load
Healthy 10.53 10.53
10%Eccentricity 11.11 12.496
20%Eccentricity 14.64 16.383
Full
load
Healthy 28.2 28.2
10%Eccentricity 48 53
20%Eccentricity 101 123
From Table 5, it is observed that the magnetic torque
increases when the level of eccentricity increases,
i.e., under the healthy condition, the magnetic torque
obtained is 1.24N-m. During static eccentricity for
10% eccentricity, the magnetic torque obtained is
2.0685N-m, for 20% eccentricity, the magnetic
torque obtained is 2.97N-m. During dynamic
eccentricity for 10% eccentricity, the magnetic
torque obtained is 2.45N-m, for 20% eccentricity,
magnetic torque obtained is 3.061N-m for no load.
Hence this observation shows an increase in the
percentage change. Similarly values are tabulated for
half and full load condition.
(a) (b)
Fig 10. Graphical representation of magnetic Torque under
various load conditions (a) Static analysis (b) Dynamic
analysis
From the graph, it is observed that magnetic torque is
increased when the percentage of eccentricity
increases.
8. Validation for Transient analysis
The simulated values of stator current, flux
linkage and torque are tabulated under various load
conditions for both healthy and faulty motor. From
the tables the simulated values are compared to
theoretical values.
HEALTHY
CONDITION
SIMULATED
VALUE
THEORETICAL
VALUE
Stator current 39 A 38.2 A
Flux linkage 0.26 Wb 0.18 Wb
Torque 28.2 N-m 29.65 N-m
From the tabulation it is observed that the simulated
values of flux function and flux density are correlated
with the theoretically calculated values.
9. Hardware Implementation
In this section, the hardware circuit
implementation of condition monitoring of three
phase induction motor can be done using current
transformer, data acquisition card and labview
software. The performance of this circuit is evaluated
on the basis of low-voltage laboratory scaled-down
prototype.

7. 10. Block diagram
Fig 10. Block Diagram
The figure 10 shows the hardware block diagram of
three phase squirrel cage induction motor is excited
by three phase supply. Then the output current is
measured using the current transformer which
converts it into a current signal. After that the current
signal is interfaced using the DAQ into the labview
software. Using labview software harmonic analysis
will be done.
Fig 11. Complete Hardware Circuit
The above complete hardware setup is tested by
interfacing the DAQ with pc and the current
spectrum is analyzed under no load for both healthy
and faulty conditions.
Fig 12. Hardware output under healthy condition
From the figure 12 it is found that the amplitude of
current is same of 0.66A and the FFT waveform
harmonic spectrum shows us the fundamental
frequency 50Hz is dominating when compared with
other frequencies during healthy condition.
Fig 13. Hardware output under eccentricity faulty
condition
From the figure 12,it is found that the amplitude of
current is same of 0.8A for eccentricity and the
harmonic spectrum from the FFT waveform shows
us the various frequencies that are available
including the fundamental frequency of 50Hz. The
frequencies other than the fundamental frequency are
called as harmonics which is caused due to the faulty
conditions.
11. Validation of Hardware Results
Summary of hardware and simulation results are
given in table,
S.NO CONDITION
HARDWARE
RESULT
CURRENT(A)
1 Healthy 0.66 A
2 Eccentricity 0.8 A
From the above table it can be observed that current
increases in the faulty motor when compared to the
healthy motor
12. Conclusion
The performance analysis of both static and
transient 2D analysis is done for the three phase
squirrel cage induction motor under healthy and
eccentricity fault conditions. It is found that the

8. magnetic flux saturation is high at minimum airgap
position. In the static analysis The Flux Function and
Flux Density is increased when the eccentricity
increased. In the transient analysis, it is found that
the flow of current in the stator phases, stored
magnetic energy and magnetic torque produced in
the motor also increased when the percentage of
eccentricity increased. Due to eccentricity, it is found
that torque and force gets pulsated which affects the
smooth operation of the machine. The variation due
to dynamic eccentricity is much more than the static
eccentricity which will cause vibrations and acoustic
problems which will reduce the life span of the
machine. The simulated and hardware results are
verified theoretically for the values like current, flux
function and flux density to validate the simulated
values.
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