Corrosion

1. 786 PIERS Proceedings, Marrakesh, MOROCCO, March 20–23, 2011
Infrared Thermography for Assessing and Monitoring Electrical
Components within Concrete Structures
Mohd Shawal Jadin1 , Soib Taib1 , and Shahid Kabir2
1
School of Electrical and Electronic Engineering, Universiti Sains Malaysia
Nibong Tebal 14300, P. Pinang, Malaysia
2
Collaborative Micro-electronic Design Excellence Centre (CEDEC)
Universiti Sains Malaysia, Nibong Tebal 14300, P. Pinang, Malaysia
Abstract— The paper presents the application of infrared thermography (IRT) for assessing
and monitoring electrical components within concrete structures. It is well known that the in-
tegrity of a power system is of paramount importance when it supplies electricity throughout a
facility, especially during peak time. Overloading, load imbalance, corrosion and loose connection
of electrical components can produce a thermal anomaly or hot spot. The abnormality of the
components will occur when its internal temperature reached beyond its limits. Consequently,
the overheating of the electrical component within the concrete structure can potentially result
in unplanned power outages, possible injury and fire hazard. In addition, the efficiency of an
electrical system becomes low prior to failure, thus energy is spent generating heat in the struc-
ture, causing unnecessary loses. Therefore, early prevention is required to avoid future faults
and increase the reliability of the electrical components. Conventionally, for a large building and
wide area of power distribution systems, the inspection of electrical power components within
the structure requires extra manpower to conduct the test and take a lot of time as well as cost.
Furthermore, only certified and experienced personnel can justify the severity of the problematic
components. This is due to the complex analysis and various factors should be considered during
the inspection especially when the cables are deep into the structure. Therefore, this research
proposed a new method of an intelligent monitoring system for electrical components by diag-
nosing its thermal profiles. The system uses infrared thermographic camera or thermal imager
in order to capture the thermal behavior of electrical components in the concrete structure. The
main feature of the proposed system is to automatically identify the thermal anomaly in elec-
trical components and classify its level of severity if the anomaly is detected. A new method
of inspection is introduced by implementing the combination of an advanced image processing
technique and artificial intelligence system. Finally, the system will give a complete analysis
report, including the most suitable action to be taken for the problem that was detected.
1. INTRODUCTION
In 1800, William Hershel has discovered infrared radiation and it was the first experiment that
showed there were forms of light not visible to the human eye [1, 2]. The infrared wavelength
spectrum is ranged from about 1 mm down to 750 nm. All objects emit energy proportional to its
surface temperature. As infrared energy functions outside the dynamic range of the human eye,
special equipment is required to transform the infrared energy to another signal, which can be seen
by human eye. For this purpose, infrared imagers were developed to see and measure this heat.
Nowadays, various types of IRT imager with more advanced and sophisticated features have been
developed [3]. The basic concepts of IRT imager or well known as thermographic camera is that it
can captures the image of the thermal pattern and measures the emissive power of a surface in an
area at various temperature ranges. The digital image of IRT is called as thermograms. Each pixel
of a thermogram has the specific temperature value, and the image’s contrast is derived from the
differences in surface temperature.
Temperature and the resulting thermal behavior of electrical components are the most critical
factors in the reliability of any operation or facility [4]. The abnormality of the components will
occur when its internal temperature reached beyond its limits. Electrical components such as
buried electrical cable and wiring within a concrete wall and structure can produce overheating
whilst under load. This will result a high surface temperature over a buried electrical supply and
can, of course, indicate a potential of fire risk [5]. In addition, the efficiency of an electrical supply
becomes low prior to failure, thus energy is spent generating heat, causing unnecessary loses.
IRT camera can detect the abnormality of power components without interrupting the power
system operation. However, most of the inspection can only be done by well-qualified and ex-
perienced personnel. Otherwise, the inspection will result a wrong interpretation. Commonly,

2. Progress In Electromagnetics Research Symposium Proceedings, Marrakesh, Morocco, Mar. 20–23, 2011 787
the thermographic inspection of electrical components will take a lot of time and high inspection
cost [6]. Therefore, applying an automatic analyzing system can overcome this situation. The
thermal abnormality of electrical components can be detected with quickly and accurately even the
expert or experienced personnel are not present. This paper proposed an automatic IRT diagnosis
system for monitoring the reliability of electrical power components.
2. TYPICAL FAULTS IN ELECTRICAL COMPONENTS
All electrical devices are usually rated for power, which indicates the amount of energy that the
devices can conduct without being damaged. If the device is operated at a power above its specifica-
tions, the excess power can reduce the device’s life cycle and efficiency. Basically, faults in electrical
power system can be classified into few categories, i.e., poor connection, short circuit, overloading,
load imbalance and improper component installation [3, 7–11]. In most cases, the major cause of
overheating in utility components is the change in resistance due to loose connection [12]. The
loose connection causes electricity to use smaller area of the defective connection than required for
proper current flow and therefore, increases the resistance and temperature of the connection. Any
problem, which accompanies a change in resistance of the equipment, causes it to consume more
power than the intended load.
According to a thermographic survey conducted during the period of 1999–2005 [13], it was found
that 48% of the problems were found in conductor connection accessories and bolted connections.
This is mainly resulted from the loose connection, corrosion, rust and non-adequate use of inhibitory
grease. On the other hand, 45% of the thermal anomalies appear in disconnectors contacts. Most
of the anomalies are due to deformations, deficient pressure of contact, incorrect alignment of arms
and dirtiness. Only 7% of the problems were found in electrical equipments.
Another major cause of overheating in electrical components within the structure is overloading.
Through IRT camera, the sign of overloading can be seen clearly even if the cable was located deep
into the concrete where the red region which has high temperature value covered all parts of the
components or cables. Fig. 1 shows an example of overheating due to overloading in an electrical
cable within a concrete wall. By utilizing IRT technology, the thermal image will clearly indicates
the problematic area. The suspected area can be easily indentified and interpreted. Nevertheless,
in some cases, the interpretation of thermographic image cannot be done directly except for an
experienced and qualified thermographers. There are some thermographic characteristic should be
understood.
3. SYSTEM DEVELOPMENT
Conventional inspection of electrical power components requires a large amount of workers as well
as time and cost. In this exercise only certified and experienced personnel can justify the level
of severity of the suspected components. This is due to the complex analysis and various factors
should be considered during the inspection. Therefore, this research proposed a new method of
intelligent monitoring system for electrical power equipments by diagnosing its thermal profiles.
3.1. System Configuration
The main feature of the proposed system is to automatically detect the thermal hot spots and
potential fault location within the concrete structure. The development of monitoring system is to
analyze the running state of electrical components using the combination of artificial intelligence
and advanced image-processing technique. The general block diagram of the proposed system is
shown in Fig. 2.
Figure 1: IRT image of cable fault in concrete wall.

3. 788 PIERS Proceedings, Marrakesh, MOROCCO, March 20–23, 2011
Figure 2: General block diagram.
Figure 3: General structure of the analyzing process.
The image of the electrical components within the concrete structure is captured and then
sends to the monitoring system for further analysis. It is a very challenging task in recognizing the
electrical equipments from the complex background in order to judge whether troubles has happened
or potential troubles would happen and finding position of suspected equipments. Therefore, an
image processing technique must be applied to filtering and enhancing the captured image. The
overall process of the system includes several steps: images’ preprocessing, feature extraction, type
recognition, state analysis and classification. After capturing the IRT images, the computer must
preprocess the images in order to improve images quality, including images’ smoothing, eliminating
noise, filtering, enhancing edges, etc. the next step is finding the interest region by segmenting the
images. The segmentation process will highlight the hot spot in the suspected component. The
image features then become the inputs of neural network that has been trained.
3.2. Faults Classification
Analysis of thermal signatures and the relation to various operating parameters must be accom-
plished. The task of determining fault modes is essentially a pattern recognition problem that is
an ideal application for a neural network. For this reasons, multilayer perceptron (MLP) neural
network (NN) will be implemented to achieve this. The general structure of the analyzing process
is shown in the Fig. 3. The difficulty of the research is to get the accurate reading of the actual
temperature of the electrical power equipments. This is due to various factors that will affect the
measurements. The factors can be classified into two categories, i.e., internal factors and externals
factors. Internal factors are related to the target components such as the component’s emissivity
and thermal gradient. External factor is about the environmental factors such as wind speed, pre-
cipitation, solar radiation and ambient temperature. Prior to analysis, all the related data must be
collected as the input variables. Therefore, a set of sensors for data acquisition is required.
The output will be justified according to qualitative and quantitative analysis. By combining
these two methods, it is expected to increase the accuracy of inspection. The level of severity
of the suspected electrical equipments in the concrete structure can be classified according to
standards [14] as shown in Table 1. The recommended action should be taken according to the
level of priority. The final process of the inspection is preparing the analysis report. Analysis
report will contain all the required information for the future analysis and maintenance. This will
include the location, date, specific problem, corrective action, infrared image and visible light image.
Additional specific information related to equipment’s temperature vs. acceptance criteria, ambient
temperature conditions, equipment’s load (for electrical equipment), and type of IRT camera are
useful for subsequent data analysis and future inspection.

4. Progress In Electromagnetics Research Symposium Proceedings, Marrakesh, Morocco, Mar. 20–23, 2011 789
Table 1: Classification of thermal profile of electrical components.
Priority ∆T (◦ C)-similar components ∆T (◦ C) over ambient Recommended Action
4 1–3 1–10 Minor problem
3 4–15 11–20 Repair as time permits
2 --- 21–40 Serious problem
1 > 15 > 40 Critical, Repair immediately
4. CONCLUSION
It is clearly shown that early prevention is required to avoid future faults and increase the reliability
of the electrical power components within concrete structure. Since the electricity demand has
increased day by day, IRT inspection should be done regularly especially in building where most of
the electrical cable or components are within the concrete structure. By implementing an automatic
diagnosis system, it can provide faster and more accurate IRT analysis for hazard protection. The
classification procedure is a useful tool and plays an important role in predictive and preventive
maintenance program.
ACKNOWLEDGMENT
This research was supported by Fundamental Research Grant Scheme (FRGS), Universiti Sains
Malaysia and Universiti Malaysia Pahang.
REFERENCES
1. Lizak, F. and M. Kolcun, “Improving reliability and decreasing losses of electrical system with
infrared thermography,” Acta Electrotechnica et Informatica, Vol. 8, No. 1, 60–63, 2008.
2. Chou, Y. and L. Yao, “Automatic diagnostic system of electrical equipment using infrared
thermography,” Proceedings of International Conference of Soft Computing and Pattern Recog-
nition, 155–160, 2009.
3. Braunovic, M., N. K. Myshkin, and V. V. Konchits, Electrical Contacts Fundamentals, Appli-
cations and Technology, CRC Press, 2007.
4. Chuck, H., Handbook of Nondestructive Evaluation, 1st Edition, McGraw-Hill Professional,
2001.
5. Epperly, R., G. Heberlein, and L. Ead, “A tool for reliability and safety: Predict and pre-
vent equipment failures with thermography,” Proceedings of Petroleum and Chemical Industry
Conference, 59–68, 1997.
6. Cao, Y., X.-M. Gu, and Q. Jin, “Infrared technology in the fault diagnosis of substation
equipment,” Proceedings of International Conference on Electricity Distribution, China, 2008.
7. Balaras, C. A. and A. A. Argiriou, “Infrared thermography for building diagnostics,” Energy
and Buildings, Vol. 34, 171–183, 2002.
8. Dos Santos, L., E. C. Bortoni, L. E. Souza, G. S. Bastos, and M. A. C. Craveiro, “Infrared
thermography applied for outdoor power substations,” Proceedings of SPIE, 69390R-69390R-
11, 2008.
9. Hou, N., “The infrared thermography diagnostic technique of high-voltage electrical equip-
ments with internal faults,” Proceedings of International Conference on Power System Tech-
nology, 110–115, Beijing, China, 1998.
10. Kregg, M. A., “Benefits of using infrared thermography in utility substations,” Proceedings of
SPIE, 249–257, 2004.
11. Azmat, Z. and D. Turner, “Infrared thermography and its role in rural utility environment,”
Proceedings of Rural Electric Power Conference, B2/1–B2/4, 2005.
12. Mart´ ınez, J. and R. Lagioia, “Experience performing infrared thermography in the maintenance
of a distribution utility,” Proceedings of International Conference on Electricity Distribution,
Vienna, 2007.
13. Titman, D. J., “Applications of thermography in non-destructive testing of structures,” NDT
& E International, Vol. 34, No. 2, 149–154, 2001.
14. “Standard for infrared inspection of electrical systems & rotating equipment,” Infraspection
Institute, 2008.