IoT and Artificial Intelligence for Fault Classification in High
Efficiency Motors
Carlos Guerrero
a
, Fernando Villegas
b
, William Oñate
c
and Gustavo Caiza
d
Universidad Politécnica Salesiana, Quito 170146, Ecuador
Keywords: Intelligent Classification, Incipient Failures, Standard Deviation Statistical Tool, Classification Deep Neural
Network, IoT.
Abstract: High-efficiency three-phase induction motors are used in most industrial production processes; however, its
malfunctioning may cause unexpected interruptions, putting at risk both manufacturing operations and
operators. Consequently, it is desired to diagnose in real-time the most common incipient failures that may
occur in this type of rotating machinery. Thus, this document presents a study of intelligent classification of
incipient failures in an induction motor, diagnosis that is visualized from a dashboard in the cloud through a
one-way IoT architecture. Using the traditional Park transform technique, torque (iq) and magnetizing (id)
currents were obtained and analysed through the standard deviation statistical tool, to identify the dispersion
of their operating amplitudes when the motor is at normal (H) or faulty (ECF and SC) operation conditions;
these values were normalized and provided as input data to a classification deep neural network. The results
given by this AI technique in the diagnosis, for both the iq and id components, showed a mean accuracy of
100% for SC and a mean classification error of 20% and 25% for H and ECF, respectively.
1 INTRODUCTION
Three-phase induction motors are very important in
industry since they take part of most production
processes, showing to be robust, low-cost and easy to
maintain (Bessous, 2020)(Torres et al., n.d.).
Nevertheless, their malfunctioning may cause
unexpected interruptions of operations (Otero et al.,
2020).
Some methods traditionally used for maintenance
of induction motors include: motor current and motor
voltage signature analysis (MCSA and MVSA),
Hilbert-Huang transform (HHT), continuous wavelet
transform (CWT) (Saucedo-Dorantes et al., 2017),
Park vector demodulation (PVD) (Oñate et al., 2022)
and statistical analysis (Torres et al., n.d.). However,
the operator should be trained to understand the
statistics of the plots, either time or frequency-
domain, considering that many of these publications
indicate possible ambiguities in the diagnosis. Being
aware of current manufacturing processes and the
a
https://orcid.org/0000-0002-8764-3847
b
https://orcid.org/0000-0002-0797-812X
c
https://orcid.org/0000-0001-6982-2502
d
https://orcid.org/0000-0002-8227-7227
parts that constitute the industry of this era (Castellino
et al., 2020), it is important to have intelligent systems
that operate in real-time and facilitate the decision-
making process for operators (Alberto et al., 2021).
Consequently, there are currently being developed
systems that integrate traditional and intelligent
methods, such as (Yang et al., 2016), (Prins et al.,
2018), (Ghosh et al., 2020) and (Zamudio-Ramirez et
al., 2020), with a predominance of MCSA and Park’s
vector modulus (PVM) for a single component; such
studies consider as focal point the diagnosis of broken
bars (BRB) and bearings (BF) failures, side-lining
other common incipient failures such as short-circuit
(SC) and eccentricity (EF), which account for 38%
and 10% of the cases, respectively (Bessous,
2020)(Otero et al., 2020)(Dhamal & Bhatkar, 2019).
Thus, the purpose of this work is to provide the
operator with access to a dashboard in the cloud for
visualizing failure diagnosis through a one-way
architecture. The system carries out the ADC of the
stator currents supplied to the motor, then extracts the
Guerrero, C., Villegas, F., OÃ
´
sate, W. and Caiza, G.
IoT and Artificial Intelligence for Fault Classification in High Efficiency Motors.
DOI: 10.5220/0011949200003612
In Proceedings of the 3rd International Symposium on Automation, Information and Computing (ISAIC 2022), pages 405-409
ISBN: 978-989-758-622-4; ISSN: 2975-9463
Copyright
c
2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)
405
iq and id components through Park transform, and
further identifies the operating amplitudes of the
motor currents with and without failure using the
standard deviation. This process will enable to feed
the input layer of a deep neural network for
classifying the operating state of the motor as being
in good or faulty conditions (H, ECF and SC).
This document is constituted by section 1
introduction, section 2 methodology and procedure,
section 3 analysis of results and finally conclusions in
section 4.
2 METHODOLOGY AND
PROCEDURE
Figure 1 shows the different stages that constitute the
failure diagnosis system, starting with the data
acquisition of the three-phase stator currents of the
motor, which is operated in a testbench as shown in
Fig. 1. Afterwards, Park transform is used to calculate
torque and magnetization currents that vary with
time, and the standard deviation is applied to this data
as a statistical tool to analyze its trend and enable the
implementation of a neural network for failure
diagnosis, which are further sent to a server in the
cloud for their visualization.
Figure 1: Block diagram of the proposed intelligent system
for detecting failures in a high-efficiency motor.
Figure 2 shows the test module, in which the
motor is coupled to a magnetic brake system
controlled in closed-loop to maintain the nominal
operation values.
Figure 2: Test module.
2.1 Data Acquisition
In the test module of Fig. 2, the data of the motor
currents are acquired and transformed into voltage
through a YHDC 3TA17-200 transducer. In order to
reduce the processing load on the Raspberry Pi boards
(Park transform, statistical tool and neural network),
an Arduino board was included to perform the ADC
with 10 bits and a sampling time of 10 ms. After
various experimental tests, a total of 60000 data were
acquired for each line of the three-phase system and
for each test (without failure, short-circuit and
eccentricity).
A WEG W22 high-efficiency motor is used in the
tests, intentionally causing failures such as: short-
circuit (SC) to a loop of a supply line, and eccentricity
(ECF) with a slope of 4.39° with respect to the shaft
of the magnetic brake. The motor features are
illustrated in Table 1.
Table 1: Features of the WEG W22 high-efficiency motor.
Features Valour
Number of phases 3
Number of poles 4
Nominal Voltage 220 / 380 - 440 v
Nominal Current 1.87 / 1.08 – 1.12 A
Power 0.37 KW – 0.5 HP
Frequency 60 Hz
Speed 1700 / 1725 RPM
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2.2 Park Transform and Statistical
Method
Once the data of the currents supplied to the motor
has been discretized, Park transform was applied to
obtain the torque (iq) and magnetization (id) currents
(Torres et al., n.d.)(Asad et al., 2018), which were
subject to a statistical method based on the standard
deviation to analyze the dispersion of the results when
the motor is in excellent and faulty operating
conditions (García, 2018).
2.3 Neural Network
Due to the large amount of data that may be acquired
during the operation of the motor, it was used a
classification model based on a deep neural network
with a supervised training technique. Such AI
technique consists of the following blocks: libraries
(NumPy, Keras, Pandas and TensorFlow), import the
iq and id components from an .xlsx file, split the data
for training (70%) and testing (30%), a network with
sequential architecture between input, hidden and
output layers, an SGD (Stochastic Gradient Descent)
training optimizer to stabilize the learning rate, and
thus establish experimentally a network with 3000
propagation correction cycles to reduce data losses.
Finally, the model with extension .h5 is implemented
in a board with Cortex processor. Figure 3 shows the
red squares that indicate the attributes that were
modified in the AI model for its execution.
Figure 3: AI model.
2.4 One-Way IoT Architecture
A communication architecture from the plant to a
dashboard was implemented to visualize the results of
the failure diagnosis in the Web; such architecture is
shown in Fig. 4. The tags corresponding to the results
of the neural network are sent through a Mosquitto
MQTT broker (Moreno Cerdà, 2018) to the Node-
Red service within the AWS platform (Chanthakit &
Rattanapoka, 2018), where the operator logs in
through authentication.
Figure 4: Communication architecture.
3 ANALYSIS AND RESULTS
Considering the MPU processing capacity, several
samples were used as input data to the sequential
model of the network, identifying that the component
that has the larger dispersion among the operating
amplitudes of the motor occurred for 50 samples, as
shown in Table 2., this is 70% (840 inputs) for
training and 30% (360 inputs) for experimental tests.
Table 2: Percentage operation amplitudes of the motor.
iq
Number of
samples
W/O
Failure
Eccentricity
Short-
circuit
1000 100% 98.5% 90.78%
100 100% 98.49% 88.65%
50 100% 98.48% 87.98%
25 100% 98.74% 88.16%
10 100% 98.92% 88.27%
id
Number of
samples
W/O
Failure
Eccentricity
Short-
circuit
1000 100% 98.45% 90.66%
100 100% 98.44% 88.69%
50 100% 98.44% 88.08%
25 100% 98.63% 88.33%
10 100% 98.86% 88.52%
Figure 5 shows the percentages of correct answers
of the intelligent classification system during the
diagnosis of failures in a motor, after various
functional field tests evaluated at the torque (iq) and
magnetization (id) currents.
IoT and Artificial Intelligence for Fault Classification in High Efficiency Motors
407
Figure 5: Result of motor operation.
Figure 5 shows some results to verify the
performance of the failure diagnosis using neural
networks. It was obtained a correct diagnosis in 80%
of the cases corresponding to the motor in good
condition. On the other hand, a correct diagnosis was
obtained in 75% of the cases corresponding to the
eccentricity failure, whereas a correct diagnosis was
achieved in 100% of the cases of the short-circuit
failure. Regarding the dispersion among the operating
amplitudes of the motor, Table 2 shows that the
dispersion of H with respect to ECF and SC was
1.52% and 12.02%, respectively.
4 CONCLUSIONS
In this work, a classification deep neural network was
used in conjunction with the standard deviation as a
statistical tool to define percentages of dispersion of
the operating amplitudes of the motor, obtaining a
difference of only 1.52% between H and ECF and of
12.02% between H and SC; these data were used in
the diagnosis, both for the iq and id components, with
a mean accuracy of 100% for SC and a mean
classification error of 20% and 25% for H and ECF,
respectively. The aforementioned results were
obtained with the experimental modification of
attributes in a deep neural classification model
constituted by 5 features in the input layer, each with
1200 input data (iq or id), a hidden layer with 1000
neurons and 5 outputs as classes corresponding to the
inputs. In order to contribute with the intelligent
system for diagnosing failures in induction motors, it
is foreseen to improve the amplitude of the operating
dispersions of the motor, and to avoid overlapping
conflicts in the system, it is possible to improve the
ADC of the data acquisition system.
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