International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT) - 2016
Condition Monitoring Tool for Electrical
Equipment — Thermography
Qasim Khan, Dr. Asfar A. Khan, Furkan Ahmad
Department of Electrical Engineering,
Aligarh Muslim University
Aligarh-202002, India
Qasim.rs@amu.ac.in
Abstract— Condition monitoring has become significant and
inevitable for look after of electrical system, and has engrossed
more and more attention globally. The no physical contact
property of non-destructive condition monitoring techniques is
now very significant and essential at diverse industrial process.
Though, accessibility of CM methods are multiple for distinct
problems such as partial discharge, thermal variation and
frequency response. Operational analysis of all the characteristics
for process in industries is still under progress. In this paper
assessment of various problem in operation of power transformer
and motors & insight on application of infrared thermograph as
condition monitoring technique have been methodically
conducted. IRISYS (IRI4010) thermal imaging camera is used
for condition assessment of Power transformer and motors and
necessary recommendations have been given based on the
priority table
Keywords— Infrared Thermography; Condition Monitoring;
Transformer; Motor; Preventive maintenance
I. INTRODUCTION
A necessity to ensure foretelling care on a wide range of
electrical equipment is escalating because of industrials and
utilities alarmed about electrical equipment handiness,
consistency and cost, avoiding stoppage is vital[1].The failure
forecasting, defects recognition and aging data are some of
benefits of condition monitoring that making maintenance
economic, increase equipment’s lifespan, enhancing safety
and the rigorousness of damage, as well as improving power
quality [2, 3]. CM is become a popular issue to power system
researchers as well as engineers by reason of advantages and
to better use of the existing resources under an economic
environment [4].
The CM process includes a series of steps based on
maintenance knowledge, fault analysis and prior operating
situations. Using prior data and condition, it is possible to
determine not only the probable lifespan but also, its
enhancement [5].There are numerous methods and techniques
implement to monitor the condition, such as stress tests that
measure boundary fracture strengths, surface analysis
techniques that identify the characteristics of equipment
materials and imaging techniques to detect degradation of
equipment [6,7]. Several Non-Destructive Techniques and
methods such as X-ray tomography, frequency response
Analysis, Spectroscopy, Acoustic sensor and vibration
978-1-4673-9939-5/16/$31.00 ©2016 IEEE
analysis are customarily used. Apart from that temperature is
significant and valuable factor that diagnose the health of
equipment [8, 9].
Infrared (IR) thermography along with high speed
appears today as a potent means to sense even short-lived
thermal events. It also significant implement in a lot of
applications and research topics i.e. physical characterization
of insulation and dielectrics under high electric field or high
temperature. The recent developments in instrumentation,
sensors allow increasing the three-dimensional resolution with
ultra-fine temperature mapping [10].The technique has also
been useful to analyze defects and degradation of materials on
the impact of thermal stresses [11].
This paper reviews the tests and monitors of electric
equipment using on-line monitoring technique IRT. This paper
emphasizes on Non-destructive Condition Monitoring
techniques. The CM of transformer and electric motor under
different conditions and Predict maintenance operations with
priorities.
II. CONDITION MONITORING TECHNIQUES
Condition monitoring is well-defined by means of
procedure or a method of acquisition the performance and
features of system so that observed and logged parameters can
be processed to enable the required actions need for
maintenance to prevent deterioration or failure and regulate
the lifespan. It control the health of each component or
complete equipment, the certain procedure and progress of
systems by getting its characteristics and its processing of the
data to forecast the plots [12-14]. Some characteristics of
better and advancement of condition monitoring techniques
and procedure and tabulated in Table 1.
TABLE I.
CONDITION MONITORING’S BENEFITS
Lower
Cost
More
Efficiency
Better
planning
Part of Totally
combined robotics
Simple
Design
Effective
Spare Parts
inventories
Longer life
Cycles
Maintenance
Station
Easy
System
Integrated
Device
Diagnostic
Planned
Standstills
Process data
recording
Open
Standards
Grid Tools
Expandabil
ity
Planned
Maintenanc
e
Simple
Cabling
Stability
Longer
Service
Intervals
High
Availability
Investment
Protection
is the temperature(in kelvin). Stefan–Boltzmann’s law is
derived for over all frequencies from equation 1 is given
below:
Quality assertion
Mechanical Wear
Worldwide
Service/Support
=
Thermography techniques is beneficial than other NDT
techniques by reason of its capability to study a large area
(severalm2), necessity of very brief inspection time to provide
alarms of faults and has data sequences for further analyzing
to provide quantitative information in a wide range of
materials [15]. Martínez and Lagioia proposed the different
stages along with suggested maintenance schedules for
thermal irregularities are given as [16]:
1) For Overheating above 130°C (Critical): instant
maintenance of the equipment for the repairing of the
abnormality.
2) Overheating between 100°C-130ºC
restoring of the abnormality once possible.
3) Overheating
between
75°C-100ºC
overhauling of the abnormality when scheduled.
(Priorities):
(regular):
(2)
Where q is the rate of energy emission (W),σ is the
Stefan–Boltzmann’s constant, A is the emitting surface area
(m2) and ε is the emissivity of the emitting surface for constant
and T.
The radiation calculated by the IR camera’s governed by
the temperature of the object as well as its emissivity. The
radiation approaching from the surrounding and reflected on
the object also influences the measuring. Consequently,
surrounding temperature due to effects of different sources is
also noteworthy, moreover parameters like emissivity,
separation between camera and test object and environment
conditions should also be measured to capture an accurate and
high-pitched image[20].With the advancement in applications
of IR thermography, numerous international association and
manufacturer published standards for test procedures[21,22],
electrical and mechanical inspections[23] and temperature
resolution[24].
IV. MEASUREMENT
III. REVIEW ON IR TECHNIQUES
IRT is a method to calculate the temperature at multiple
position of the surface of equipment with the effective
measurement and visualization, with maximum precision. Due
to the no physical contact with the surface, it is nondestructive in nature and non-interference with operation of
the equipment or system. This non-intrusive nature is essential
requirement in industrial applications that demands enclosed
and highly influenced by external protrusion, It may reduce
significant costs. Additionally, it reduce risky environment
and possible accidental causes for the operators[17]. Infrared
radiation measurements are utilized thermal condition and
temperature variation which are then processed and renovated
into convenient and communicative electrical signals. The
measuring unit includes an infrared camera with high
resolution, superficial temperature gradients and high
sensitivity for temperature with capability of capture of high
quality images [18].
One of the vital sources of winding insulation
deterioration is thermal stress, in spite that the topic is not
advances to efficiently monitor and process the winding
insulation temperature in operation. A procedure is implement
to condition monitor the equipment such as transformer and
motors using thermal imaging of the motor, transformer
applying thermal camera. Hotspots can therefore be mapped
at different positions over equipment. Experimental setup
includes110/33 kV transformer set of induction motor drive
system and thermal camera. Thermal Images are captured
using IRI thermal camera with great care, maximum resolution
and be in line of sight. When thermal images are taken
improperly, images show minimum unclear difference
between the main objects and their backgrounds, dull in color,
it must not be processed to determine the situations and
monitoring report.
C. Meola [19] explains thermal radiation theory i.e.
blackbody is defined as an imaginary object which absorbs all
incident energies and emits a constant spectrum whose power
is according to Planck’s law as given below.
As unusual condition from infrared detections are generally
elucidated by the extreme temperature limits, selecting
multiple motors system of different condition and
deterioration. Temperature condition at different position on
each unit is observed and tabulated. By analyzing extreme
temperature variations, it is to recognize probable defects and
its location on different equipment and suggest the priority
based maintenance action for staff people responsible for
repair and maintenance to specific equipment. After analysis
thermal imager of transformer and motor at various
conditions, recommended action is suggested according to
priority is tabularized as shown in table 2.
=
(1)
Wherec1 and c2 are the first and second radiations
constants respectively, is the wavelength of the rays (µm),
is the emitting power of the blackbody per unit area and per
unit solid angle for a particular wavelength (Wm2µm-1sr-1), T
A. IRI 4000 SERIES THERMAL IMAGER
The IRI 4010 is a pioneering thermal imaging tool with
exceptional imaging and temperature recording capability( 10ºC to +250ºC) in combination with the customary IRISYS
features of portability, accessibility and hot spots can be
recognized by use of at rigger activated laser pointer and
economic for ownership.
IRISYS operated according to international standards [2224] has captured an image that is superlative for the researcher
and maintenance engineer. High quality images can be
captured and handled offline or self-resolved capability on the
spot with accessibility of IRISYS ISI 4604-4000 Series
Imager Software [25] that enhanced functions and ease in
image processing methods. The user-friendly camera based on
configured with large 31/2" LCD and LED backlight display
screen. are unavoidable.
thousands of points at once as compared to an infrared
thermometer that only capture temperatures at a sole point.
The thermal image for the entire critical motor drive
component and all it hotspot is shown in Fig. 2.
(a)
(b)
Fig. 2. Infrared image of the motor during various operational stresses.
(a) The image shows the positive temperature difference between two
cursors at certain operation condition. (b) The image shows the zero
temperature difference at critical condition
(a)
(b)
Fig. 1. IRI 4010 Thermal Imager
V. RESULTS
The corresponding models of electrical equipment in
Industrial unit such as substation, power plant unit, are
necessary for the computable research for the thermal stability
and temperature variation tests. Regulation of the internal
heat-transferring process will be useful for the further research
on the diagnosis criterion of internal defects by thermograph
images. The Fig.1 shows the Thermal image as well visible
image of electric motor. The variation of temperature at
different points inside the motor is represented by different
colors. The two cursor shown in Fig. 1(a) shows temperature
and analyze the health of motor. The Fig. 1(b) shows the
minimum temperature difference and represents the critical
condition of motor. A thermal image capture temperatures at
Fig. 3. Infrared thermography can also be used for condition monitoring
of electrical machine, (a) Visible Image of the motor drive end Bearing, (b)
Infrared Image shows the hot spot temperature and temperature difference
between normal temperature and hotspot.
Failures existing in transformers are usually due to
overheating or hot spots, making thermal imaging a good tool
for finding defects and irregularities. Not always
thermography searching for hot spots or hot areas, in some
cases colder areas turn out to be fatal harms. Transformers
provided with fins arranged in set that naturally circulate the
oil for maintain the temperature of transformer as each fins set
present around the core and work as a radiator. The IR image
of Figure 4 shows a 110/33 KV transformer, we see that the
upper part of the transformer is bright or hot, whereas the
lower part is dark or cold, this is due to improper circulation of
the oil which lead to temperature difference. From the figure
4(b), we see that one of the radiators seems to be cold, and this
may be due to present of impurities or over heating of some
component in directly influenced cooling efficiency which
will overheat winding rapidly and raise the probability of
damage or failure of the transformer affiliations.
(a)
72
30
43
(b)
Fig. 4. (a) Infrared Imaging of electrical transformer showing temperature
of upper hotter portion and lower cooler portion (b) Infrared Image and
visible image shows the hot spot.
TABLE II.
thermograph improved performance of machine as well as
reduce fault clearance time, continuous productivity and ideal
maintenance scheduling. Moreover, applications of
thermography have well established its position in order to
know the potential energy saving possibilities. With the
developments in instrumentation, it has been expected that low
budget IR thermo vision instruments will be available in near
future, thereby making its usage more user friendly and
growing the application elsewhere.
The development of various image processing techniques
enhance the investigation of infrared thermal images together
with artificial intelligence programming reduces the human
interference and self-decision capability making process
quicker and cutting-edge. Dissimilar the rest of CM tools,
infrared thermography offer an instantaneous high resolution
color implied image of the object and visible representation of
fault. Scope of Thermography is expanding and becoming
preferred tool for performance evaluation not only electrical
and mechanical systems as well as civil engineering, material
degradation, nuclear and aerospace engineering and industries
application. The handiness of IRT would permit operator in
small industries to use thermal imaging with no trouble for
various applications, which would reduce lost time,
maintenance budget and accidental situation and improve the
yield and progress. Cautious assortment of testing criteria in
combination with effective data analysis techniques lead to
high degree of accuracy and precision in thermography based
tool that reduces false alarms circumstances and hasty failures.
References
PRIORITY INDEX
Priority
∆T between
similar
components
under similar
load ( )
∆T over
ambient
temperature
(
Recommended action
4
1-3
1-10
Possible deficiency,
deserves investigation
(a)
[1]
[2]
[3]
3
4-15
11-20
Possible deficiency,
Scheduled investigation
2
-
21-40
Monitor till corrective
actions be performed
[4]
1
>15
>40
Major discrepancy;
repair immediately
[5]
VI. CONCLUSION
[6]
[7]
IR thermography is gaining significance in practically all
industrial application. This diagnosing tool assisting the
engineer and operators to maintenance health and also foretell
any potential failure, so shut down the equipment before fail.
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transformer and motor is elementary necessity in any industry
and utilities, Priority table suggested implementing
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