The Effect of Tuned Compensation Capacitors in the
Induction Motors
MATHEW HABYARIMANA, GULSHAN SHARMA, PITSHOU NTAMBU BOKORO
Department of Electrical and Electronic Engineering Technology,
University of Johannesburg,
Doornfontein Campus,
SOUTH AFRICA
Abstract: - The load switch-on surge current phenomenon is a key problem for remote loads generally
connected to weak or stand-alone grids. This has been the main research topic in smart microgrids. A
correlation exists between the motor load and the starting current since a motor usually needs a larger starting
current to overcome inertia. Both the power needed to start the load and the higher reactive power demand
during the starting procedure are at the origin of the increased current. The current decreases to the nominal
value for the specific load gradually after the motor starts. This relationship is essential for figuring out the
dimensions of electrical components and protecting the grid and motor from harm. Depending on the load, the
switch-on surge current is greater than two to ten times the rated full load current. Energy storage systems can
make up for the higher power needed to protect the load and the grid connection. It makes more sense to use
tuned compensating capacitors to reduce the reactive power required to reduce the inrush current. The primary
focus of this work is the selection, calculation, and switching of the capacitor bank for reactive power
compensation. Following the previous research, in this paper, the smaller 2HP induction motor load is
examined. The capacitances are calculated, turned on to offset the starting transient, and then disengaged once
the machine reaches operating speed. This is done by using a point-on switching technique that lowers the
switching transient.
Key-Words: - Point on switching, Capacitor bank, micro-controller, Compensation.
Received: April 23, 2023. Revised: February 24, 2024. Accepted: June 12, 2024. Published: July 4, 2024.
1 Introduction
Large loads' inrush currents in power systems can
result in issues with excessive current drawn and, in
the case of weak grids, can destroy both the system
equipment and the system network. Additionally, it
may inadvertently set off protective relays, causing
voltage drops that impair the functionality of
additional devices connected to the same system.
The goal of this research is to use capacitor
switching to reduce inrush current.
Three-phase induction machines can be started
in various ways to handle peak current and pulsing
torques during the startup phase. For the machine's
electrical protection unit, mechanical gearing
systems, and electrical suppliers, this kind of
performance is highly undesirable.
When a motor is connected to a power source
that isn't strong enough, the abrupt increase in
current leads in a temporary drop in voltage
throughout the entire power bus, which powers the
starting motor, [1]. In this study, a model for
reducing inrush current on a power-rated induction
motors in remote locations from the main grid and
standalone microgrids is presented.
2 Literature Review
The issue of protection relays tripping unnecessarily
or falsely is what sparked interest in the study of
inrush current phenomenon, [2], [3], [4]. Five
fundamental techniques were employed to start
induction motors, [5], [6]. Excepting the direct
online (DOL) starting, a starting method’s primary
goal is to lower the motor’s supply voltage to lower
the inrush currents specifically during the starting
process. This is due to the supply voltage that
directly impacts the starting currents.
However, there are advantages and trade-offs in
terms of performance for every approach; When
they first start, they all use the grid frequency.
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
242
Volume 19, 2024
Fig. 1: Three phase Induction Motor name plate
Modern starting techniques such as part winding
arrangement and adjustable frequency drive (AFD)
have been developed and some drawbacks were
investigated in [5] and [7].
Based on the overall power system restrictions
and the drive equipment, this study develops a way
to minimize the starting current without requiring
more motor design at a fair cost. Reactive power
consumption is high in induction motors because
they often have a relatively low power factor when
they initially start. In the previous study the motor
that was investigated in the experiments 5HP was
bigger than the current one 2HP, to show the
experimental results based on sizes.
The purpose of adding the capacitors in the
motor control circuit is to enable it to function as
generators of reactive power. The calculation of the
initial peak of inrush current was the main task of
early approaches (Table 1), [8], [9]. As previously
used for the 5HP motor, in this research’s suggested
approach makes use of microcontroller
programming with an algorithm written so that the
network’s capacitors are switched on whenever the
current exceeds a predetermined value, ”X,” for the
2HP induction motor which represents both the
inrush current and the starting period, which can
also be determined by a low power factor (1).
(1)
Where and are are phase angles for
voltage and current respectively, P is the total input
power, I is the input line current, and V is the line
voltage.
Depending on the steady-state conditions, the
current decreases to the specified value or less once
the motor reaches the rated speed. Since the
capacitors no longer provide the reactive power
compensation during starting, they can be carefully
replaced. This will prevent the motor from entering
a generator mode, which could seriously damage it
due to the magnetizing current the capacitors
provide and the voltage at the motor terminals rising
to nearly 50% of the rated voltage, [10], [11].
The next section discusses the point-on
switching of the capacitors.
Fig. 2: Stator connection layout
Fig. 3: Stator connection diagram
3 Motor Testing
The 50 Hz, 4 poles, 2hp, 3 Phase Induction motor
used in this research has been tested to get the
practical parameters used in the capacitor sizing and
switching. Figure 1 shows the nameplate of it.
The instruments that are required are shown in
Table 2. The synchronous speed and the Coil span
(full pitch) are respectively given by (2) & (3).
(2)
(3)
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
243
Volume 19, 2024
Table 1. The Various Starting Methods and Characteristics, [10]
DOL
Auto
Trans-
former
Solid State
Starters
Adjustable
Freq. Drives
Primary Resistor
/
Reactor
Part
Winding
Wye Delta
Initial System Cost
Low
Moderate
Higher
Highest
Moderate
Low
Low
Starting Current
Highest
Low
Moderate
Lowest
Moderate
Moderate
Low
Starting Torque
Highest
Low
Low
Highest
Low
Low
Low
Table 2. Required Instruments
S. No.
Name
Range
Qty
1
Ammeter
5A
1
2
Voltmeter
0-500
1
3
Wattmete
5/10A, 150/300/600V
2
4
3 phase Variac
6A
1
Table 3. Coils Inter Connection Terminal Coding
Phase A
Phase B
Phase C
1 (Input Terminal Point)
17 (Input Terminal Point)
33 (Input Terminal Point)
2-3
18-19
34-35
4-5
20-21
36-37
6-7
22-23
38-39
8-26
24-42
40-58
25-28
41-44
57-60
27-30
43-46
59-62
29-32
45-48
61-64
31-49
47-65
63-81
50-51
66-67
82-83
52-53
68-69
84-85
54-55
70-71
86-87
56-74
72-90
88-10
73-76
89-92
9-12
75-78
91-94
11-14
77-80
93 -96
13-16
79 (Neutral point)
95 (Neutral point)
15 ( Neutral point)
Table 4. Equivalent Circuit Parameters
Description
Data source
Symbol
Value
Stator resistance
Measured
R1
2.3
Stator reactance
Calculated
X1
3.39
Stator inductance
Calculated
Lls
5.262mH
Rotor resistance
Calculated
R2
3.13
Rotor reactance
Calculated
X2
7.91
Rotor Inductance
Calculated
L1r
5.262mH
Core resistance
Measured
RC
222.78
Magnetizing reactance
Calculated
Xm
95.48
Magnetizing inductance
Calculated
Lm
178.91mH
Number of poles
Number plate
P
4 poles
Rated stator voltage
Number plate
V rated
220 V
Rated rotor speed
Number plate
N rated
1485 rpm
Supply frequency
Number plate
f
50 Hz
Inertia constant
Calculated
j
0.012
Total Number of stator coils per phase
counted
Ns
16
Table 5. No Load Motor Test Results
Measurement Value
Value
Line to line voltage, VL-L
220 V
Line current, IL
2.7 A
Rotor speed
1484 rpm
Supply frequency
50 Hz
Stator resistance, R1
2.1293 Ω
W1,nl = 90x2=180W
Three phase power with 2 Wattmeters
W2,nl = 83x5=415W
Pnl = 595W
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
244
Volume 19, 2024
Fig. 4: Running light test - variation of current with
voltage
Fig. 5: Running light test current waveforms
This is a four-pole connection, meaning that
each pole’s coils are connected in series with the
poles themselves. Figure 3 & Figure 2 displays the
Stator connection diagram and configuration.
The machine specification from the nameplate is
summarized as follows:
• Nominal Current: 3.7 Amperes per terminal
• Nominal voltages: 380 Volts
• Nominal Power: 2 Horse Power (1.5kW)
• Rated speed: 1400 rpm
• Network frequency: 50 Hz
• power factor 0.79
• efficiency 78.5%
Table 4 shows the equivalent of circuit parameters
measured and or counted during the experiment.
3.1 Running Light Test
The Measured no-load values from the test are
shown in (Table 5).
The equivalent circuit parameters are
summarised in Table 3.
The core loss, magnetizing reactance, were
calculated as (4) and (5).
(4)
(5)
Fig. 6: Rotor loop
Table 6. Locked Rotor Test Results
V13[V]
V21[V]
V32[V]
ILinemean[V]
I1[A]
I2[A]
I3[A]
ILinemean[A]
160.5
147.8
150.3
152.87
1.44
1.44
1.44
1.44
175.5
178.8
176.3
176.87
1.78
1.96
1.64
1.79
200.3
198.6
200.8
199.9
2.19
2.4
2.09
2.23
220.1
218.3
220.6
219.67
2.69
2.85
2.51
2.68
252.3
250
252.2
251.5
3.68
3.77
3.39
3.61
302.3
300.1
302.2
301.53
6.02
6.06
5.63
5.9
332.9
332.9
332.9
332.9
7.8
7.84
7.51
7.72
350.2
347
347.5
348.23
9.19
9.19
8.73
9.04
Table 7. Locked Rotor Test Measurements
Line to line voltage
Vbl,L−L
46 V
Line current
IL
5.8 A
Supply frequency
f
50 Hz
Stator resistance
R1
1.5244 Ω
Three phase power, 2 Wattmeters
Pnl
W1,nl = 90x2=180W
W2,nl = 83x5=415W
W1 +W2= 595W
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
245
Volume 19, 2024
(6)
(7)
The power factor is given by (8)
(8)
(9)
The no load impedance per phase (10):
(10)
The No load resistance per phase (11):
(11)
The No-load reactance per phase is (12):
(12)
The IV curve for the no load test is show on
Figure 4.
As seen in Figure 5, the current wave-forms
were also examined. Because of the short-pitched
winding and saturation, these exhibit some
distortion.
3.2 Locked Rotor Test
This test is conducted at a much-reduced voltage
with a rated full-load current and with the rotor
firmly locked so that it does not rotate.
The machine is supplied by an auto-transformer
so that the voltage can be increased slowly. For this
test, the current flowing through the magnetizing
components is assumed to be negligible since the
voltage is so much reduced (perhaps only 10 % of
the rated voltage). In this case, we can assume that
all the current is flowing through the rotor loop
(Figure 6) and the results are shown in Table 6 and
Table 7.
The power is measured with the 2-wattmeter
method, each wattmeter with the multiplying factor.
The no-load impedance per phase (13):
(13)
The stator + rotor resistance (14):
(14)
Stator and rotor leakage reactance (15):
(15)
The power factor (16):
(16)
4 Simulation Results
To achieve a complete conclusion for this research
that started before, [12], [13], seven different
induction machine properties have been examined,
spanning a broad range of power, voltage, and pole
number. The first was a laboratory motor (3) with
four poles and 5 hP at 346 V. During the
experiment, the machine’s voltage was de-rated to
220 V.
The testing procedure and outcomes for the
running-light and locked-rotor tests are shown in
Table 5.
Fig. 7: P.U. input resistances and reactances at start
for different motors
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
246
Volume 19, 2024
Fig. 8: Variation of P.U. Xm and Rc for different
motors
To compare with the laboratory machine, there
is a 1.5 kW (2hP), 380 V, 4-pole, 50 Hz machine; a
larger LV machine is represented by a 45 kW, 400
V, 4-pole, 50 Hz machine; an example of a higher-
speed MV machine is a larger 2-pole, 200 kW, 3300
V machine; and an example of a larger MV low-
speed motor is a 1 MW 6-pole, 6000 V.
The firm website, [14], included data sheets and
test reports, including running-light and locked-rotor
test results. Two example machines that [15],
analyzed are included to add even more machines to
the mix; these are examples of 60 Hz machines to
provide variance. As an example of a very big MV
machine, there is a modest 3.75 kW, 440 V, 4-pole,
60 Hz machine and a very huge 3.75 MW, 6900 V,
12-pole, 60 Hz machine. The parameters displayed
by these machines are diverse and can be found in
Table 8. The parameters were computed using data
from running-light and locked rotor tests, or they
were derived from manufacturer data sheets.
Table 9 contains the equivalent circuit
parameters for each phase, either measured through
testing or derived from the sources. The reactance
resistance at startup is represented by the ratio X/R,
and it is evident that larger machines are often
significantly more inductive than smaller machines
at this point. Figure 7 displays the initial power
factors, which support the overall pattern of the
power factor at start declining with increasing size.
While the power range of the machines under study
likely encompasses the entire range of 3-phase
induction motors available, this is obviously largely
dependent on the motor design. The power is on a
logarithmic scale, as you can see.
Fig. 9: Power factor start for different motors.
The normalization is done using (17).
(17)
Figure 8 shows the P.U. values for
and
plotted versus motor power. Be aware that
the scale on both axis is logarithmic. As can be
shown,
fluctuates with a general trend
downwards with increasing motor power, but
is largely constant across the spectrum,
with the 1.5kW lab machine serving as an exception
of Figure 9 plots Xm and Rc. The two axes are
logarithmic once more.
With increasing power, the magnetizing
reactance Xm shows a little increase trend but
remains almost constant. The lab machine is an
anomaly once more, with a much lower core loss
resistance. The core loss resistance is significantly
larger and follows the same rising pattern (Table
10).
The overall simulink model is shown in Figure
10 and Figure 11 shows the waveforms for lab
Motor with Capacitors.
5 Experimental Procedure and
Calculations
The switching of capacitors is done following
specific conditions and using the programmed
microcontroller. This will reduce the inrush current.
There are two types of capacitor connection; star (or
Wye) and delta. In this research, the capacitor will
be connected in delta. Star-connected capacitors for
motors are not an appropriate connection and can
potentially cause a failure to not only the capacitor
but to the motor as well. For the star connection,
capacitors are not grounded and can present a
potential difference on each phase of the capacitor
therefore contributing to the deterioration of the
motor and capacitors connected.
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
247
Volume 19, 2024
Table 8. Motor Parameters
No.
Machine
kW
V Line [V]
I Line [A]
Poles
fs [Hz]
rpm
J[kg.m2]
1
Lab machine
1.5
220
5.8
4
50
1425
0.0 12
2
Valiadas K90L-4
1.5
400
3.3
4
50
1440
_
3
Sen 5 HP
3.75
440
3.73
4
60
1753
0.05
4
Yaliadis K200L-4
45
400
8 1. 1
4
50
1480
0.246
5
Valiadas KHV355-2
200
3300
44.4
2
50
_
2.6
6
Valiadas TMKHV560-6
1000
6000
110
6
50
990
79
7
Sen 5000 HP
3730
6900
358
12
60
596
145.47
Table 7. Motor Equivalent Circuit Parameters (Values in Ω)
No.
Machine
Xm
Rc
R1
′
′
1
Lab machine
58
81
2.13
1.34
2.99
0.86
2
Valiadas K90L-4
115.2
1568.2
1.325
3.87
8.44
1.62
3
Sen 5 HP
110
900
1.2
1.5
6
2.22
4
Valiadis K200L-4
5. 13
178.1
0.059
0.0 13
0.48
6.67
5
Valiadas KHV355-2
118
1333
0.79
0.57
5.75
4.2
6
Valiadas TMKHV560-6
102.5
900
0.97
0.24
4.78
3.97
7
Sen 5000 HP
46
600
0.083
0.08
2.6
15.95
Table 80. Motor Equivalent Circuit Parameters (Values in P.U.)
No.
Machine
Xm
R2
R1
′
′
1
Lab machine
37.478
1.54
2.17
0.0568
0.0357
0.08
2
Yaliadas K90L-4
69.98
1.65
22.41
0.189
0.0554
0. 121
3
Sen 5 HP
36.29
3.03
24.8
0.0331
0.0413
0. 165
4
Yaliad is K200L-4
2.85
1.8
62.56
0.0207
0.0046
0. 169
5
Yaliadas KHY355-2
42.91
2.75
3 1.08
0.0184
0.0314
0. 134
6
Valiadas TMKHY560-6
29. 11
3.5
40
0.0332
0.0082
0. 164
7
Sen 5000 HP
11.1 3
4. 13
53.92
0.0075
0.0072
0.234
Fig. 10: Simulink mode
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
248
Volume 19, 2024
Fig. 11: Transient simulation of lab Motor with 90 μF capacitors
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
249
Volume 19, 2024
The failure of the capacitor causes motor
breakdown because it makes the load unbalanced
(Figure 13) therefore the motor is gets damaged
following the unbalanced voltage and overheat
which will eventually burn it out, [16]. Unprotected
Star-connected capacitors should not be used for
Power Factor correction for similar reasons. The
protection of this type of connection is costlier than
the capacitors themselves and, thus not generally
included within the connection circuit. The overall
layout of the test rig is shown in Figure 12.
Delta connection is the one chosen in this
research. It does provide capacitance to each phase
but does not provide voltage unbalance (harmonics),
[17]. In the case of a failure of one capacitor cell for
one phase for any reason, it moves from a closed
delta to an open delta configuration. In this case, the
voltage remains unchanged as shown in Figure 13.
Figure 14 illustrates the capacitor connection model
of a 3-phase induction motor used in this research;
the capacitors C1, C2, and C3 are connected in
delta. In the delta connection, capacitors are capable
of circulating harmonic currents within the circuit,
therefore reducing the harmonics of the electrical
system.
The instantaneous voltage equations are written
as (18):
(18)
Assuming the three capacitors are equal size for a
balanced
Motor , the current through
each capacitor
can be calculated from (19):
(19)
The motor parameters need to be specified to
calculate the time to connect the capacitors; in this
simulation case we use the same as in [12], as
shown in the equations (20).
start
(20)
And (21).
(21)
where is the starting capacitive reactance,
is the starting reactive power, is the
phase voltage, and C is the capacitance. The grid
frequency is 50 Hz.
The maximum voltage is given by (22)
(22)
Therefore, capacitor currents iC are, for a 50 Hz
system (23):
Fig. 12: Final layout of test rig
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
250
Volume 19, 2024
Fig. 13: The failure of any one cell of a Star and/or
Delta connected
Fig. 14: Capacitor connection model to the load
(23)
Fig. 15: Per phase equivalent circuit in the induction
motor under the no-load
The motor size may vary but the main concept
of capacitor switching remains the same.
The Machine 50 Hz, 4 poles, 2 hp, 3-phase
Induction motor is also tested with a synchronous
speed of 1500 rpm. Tests are done for parameter
determination according to its equivalent circuit
(Figure 15).
For the 4-pole connection, the coils in each pole
are connected in series.
The magnetization reactance is calculated from (24).
(24)
The power factor is (25).
(25)
so the angle is (26). (26)
(27)
(28)
(29)
The no-load impedance per phase (30):
(30)
No load resistance per phase (31):
(31)
(32)
The no load impedance per phase is given by (33):
(33)
The stator + rotor resistance (34):
4)
No load reactance per phase (35):
(35)
It is assumed that
then (36)
(36)
The stator winding (37 and 38) is obtained from
a DC measurement between two phases, where
Vdc=24.7 V and Idc = 5.8 A:
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
251
Volume 19, 2024
(37)
(38)
The reactive power is given by (39):
(39)
where (40):
(40)
The magnetizing reactance is (41):
(41)
The air-gap power and starting torque are given by
(42), (43) and (44):
gap
(42)
start gap
(43)
mech
(44)
By applying Kirchhoff’s current law, the
instantaneous input current is given by (45):
(45)
With;
(46)
(Angles to be converted in radians).
Considering the maximum current Im as Full Load
Amp (FLA) which is calculated as (47).
The given motor shows the rated FLA is 5.8 A.
Assuming the PF of 0.82 we can also find the
efficiency (48);
Efficiency
(47)
(48)
Therefore, the input currents will be given by (49)
(49)
6 Capacitors Switching to Network
A microcontroller is programmed in such way the
inserted capacitors are removed or switched off
from the network as the inrush currents reduces to
the running current; they are switched on when it
rises beyond the running current. As the magnitude
of the inrush current depends on the switch-in angle
on the voltage cycle [18], the switch must be
inserted at minimum or at 0 degrees and described
in (50):
(50)
The switching of capacitors is done in the
network when the voltage across the two phases
(line voltage between phases) is equal to zero, this is
as same as saying; at the time equal to the roots
(zeros) of the input equation and the waveforms for
shown on Figure 16.
7 Time Roots Equation Calculation
The calculation in (22) is to find the time the
switches will be triggered to insert capacitor into the
network. Besides switching the capacitors when the
voltage between two phases crosses zero, the
conditions for switching capacitors are (51):
(51)
which yields (52):
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
252
Volume 19, 2024
(52)
Considering the frequency and the
input voltage , the switching time t of the
capacitors into the network possibility between
phase and will can be calculated
from (53).
(53)
(54)
Fig. 16: Voltage va-vb plotting waveforms
(55)
Plotting the voltage and
follows the same procedure as . Since
(56)
(57)
(58)
Conditional roots which are the switching
possibilities as given by the equations may be
positive or negative values (practically, negative
values of time are omitted, which is the condition
given from the flowchart (Figure 17). Therefore, the
circuit diagram for the system is given in Figure 18.
8 Prediction Results with Simulink
In the simulation, the inrush current of a 2 HP, 3-
phase Induction Motor attains 65.71 A and starts
reducing after a delay of 5.5 s and maintains 5.8 A
for the rest of the running time (Figure 19). The
delay varies from one machine to another depending
on their parameters with respect to the network. For
the case of the considered machine also, the power
factor is given in Figure 20.
Once the conditions are met for insertion of
capacitors as discussed in Section III and also with
the size of capacitor calculated from (21); the
capacitors are inserted. The inrush current is
reduced to 49.01 A which constitutes a 25.43 %
reduction. The rotational speed and torque
characteristics are the same as the DOL case,
settling after 5.3 s to 1493 rpm as shown in Figure
21.
The comparison between currents with a DOL
and the current system is shown in Figure 19 which
illustrates the current reduction.
Fig. 17: Capacitor switching flowchart
Fig. 18: Switching circuit diagram
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
253
Volume 19, 2024
9 Conclusion
As previously shown in a prior study, [12] which
was simulation-based, it has been feasible to cut the
beginning current by 50 % with the 5 HP, three-
phase Induction motor by tweaking compensation
capacitors.
Fig. 19: Current measurements comparison
Fig. 20: Motor power factor
In this research, the results are obtained from a
small 2 HP machine where the starting current is
reduced by 25%. This may lead to the conclusion
that the larger machines are used with the same
research methodology. More research will be
carried on with more scientific aspect involved in
this scope.
Fig. 21: Electromagnetic torque
Additionally, active power adjustment can be
used to reduce current even further. However, this
will require energy storage and an inverter, but the
result will be more manageable. This will be the
subject of future research as well.
In this research the implementation is aligned
with the simulation: before connecting the control
circuit to the physical load, a Speedgoat Real-time
Simulator (the development tool
available in the lab) will be used to carry out
Hardware In The Loop (HIL) testing before testing
on a real system.
References:
[1] H. Rehaoulia and M. Poloujadoff,
"Transient behavior of the resultant airgap
field during run-up of an induction motor,"
IEEE Transactions on Energy Conversion,
no. 4, pp. 92-98, 1986.
[2] E. Kurtz, "Transformer current and power
inrushes under load," Electrical
Engineering, vol. 56, no. 8, pp. 989-994,
1937.
[3] C. Hayward, "Prolonged inrush currents
with parallel transformers affect differential
relaying," Electrical Engineering, vol. 60,
no. 12, pp. 1096-1101, 1941.
[4] M. Akherraz, "Inrush current and speed
regulation of induction motor drives," in
[1991 Proceedings] 6th Mediterranean
Electrotechnical Conference, 1991: IEEE,
pp. 1285-1288.
[5] K. Pillay, M. Nour, K. Yang, D. D. Harun,
and L. Haw, "Assessment and comparison
of conventional motor starters and modern
power electronic drives for induction motor
starting characteristics," in 2009 IEEE
Symposium on Industrial Electronics &
Applications, 2009, vol. 2: IEEE, pp. 584-
589.
[6] A. A. Shaltout, "Analysis of torsional
torques in starting of large squirrel cage
induction motors," IEEE transactions on
energy conversion, vol. 9, no. 1, pp. 135-
142, 1994.
[7] N. Ragavendra, H. Suresh, J. Mohana
Lakshmi, K. Shruthi, and T. Shruthi,
"Fabrication and Development of Signal
Loss Recovery System for AC Drives",
International Journal of Emerging
Technology and Advanced Engineering,
Vol. 3, Issue 8, August 2013, pp.164-171.
[8] L. Finzi and W. Mutschler, "The inrush of
magnetizing current in single-phase
transformers," Transactions of the American
Institute of Electrical Engineers, vol. 70, no.
2, pp. 1436-1438, 1951.
[9] P. Amiri and M. Akhbari, "Transient current
limiter for suppressing transformer inrush,
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
254
Volume 19, 2024
motor starting and fault currents in power
system," IET Electric Power Applications,
vol. 11, no. 3, pp. 423-433, 2017.
[10] J. Larabee, B. Pellegrino, and B. Flick,
"Induction motor starting methods and
issues," in Record of Conference Papers
Industry Applications Society 52nd Annual
Petroleum and Chemical Industry
Conference, 2005: IEEE, pp. 217-222.
[11] S. Chen, T. A. Lipo, and D. Fitzgerald,
"Source of induction motor bearing currents
caused by PWM inverters," IEEE
Transactions on Energy conversion, vol. 11,
no. 1, pp. 25-32, 1996.
[12] M. Habyarimana and D. Dorrell, "Methods
to reduce the starting current of an induction
motor," in 2017 IEEE International
Conference on Power, Control, Signals and
Instrumentation Engineering (ICPCSI),
2017: IEEE, pp. 34-38.
[13] M. Habyarimana, D. G. Dorrell, and R.
Musumpuka, "Reduction of Starting Current
in Large Induction Motors," Energies, vol.
15, no. 10, p. 3848, 2022.
[14] Valiadis Hellenic Motors. "OUR
MOTORS", [Online].
https://www.valiadis.gr/?view=138
(Accessed Date: July 2, 2024).
[15] P. C. Sen, Principles of Electric Machines
and Power Electronics, International
Adaptation. John Wiley & Sons, 2021.
[16] S. Jain, J. Sharma, and S. Singh, "Transient
performance of three-phase self-excited
induction generator during balanced and
unbalanced faults," IEE Proceedings-
Generation, Transmission and Distribution,
vol. 149, no. 1, pp. 50-57, 2002.
[17] C. Tindall and W. Monteith, "Balanced
operation of 3-phase induction motors
connected to single-phase supplies," in
Proceedings of the institution of Electrical
Engineers, 1976, vol. 123, no. 6: IET, pp.
517-522.
[18] I. Farzadfar, "An inrush current model for
core type transformers," 1997, [Online].
https://www.nlc-
bnc.ca/obj/s4/f2/dsk3/ftp05/mq23298.pdf
(Accessed Date: July 2, 2024).
Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting
Policy)
The authors equally contributed in the present
research, at all stages from the formulation of the
problem to the final findings and solution.
Sources of Funding for Research Presented in a
Scientific Article or Scientific Article Itself
This work was supported by the University of
Johannesbourg, Post Doctorate Research grant.
Conflict of Interest
The authors have no conflicts of interest to declare.
Creative Commons Attribution License 4.0
(Attribution 4.0 International, CC BY 4.0)
This article is published under the terms of the
Creative Commons Attribution License 4.0
https://creativecommons.org/licenses/by/4.0/deed.en
_US
WSEAS TRANSACTIONS on POWER SYSTEMS
DOI: 10.37394/232016.2024.19.22
Mathew Habyarimana, Gulshan Sharma,
Pitshou Ntambu Bokoro
E-ISSN: 2224-350X
255
Volume 19, 2024
