Basics of Thermal Imaging technology.ppt

Basic if thermal imaging

1. Thermal Imagers
1
WELCOME

2. Thermal Imagers
2
-9.4°C
74.4°C
0
20
40
60
WORKSHOP ON THERMAL IMAGING

3. Thermal Imagers
3
AGENDA
•Basics of Thermal Imaging
•Applications of Thermal Imaging
•Choosing a Thermal Imager
•Hands on Training

4. Thermal Imagers
4
What is Thermography?
•The use of electronic “cameras” to
detect radiant energy or heat
•Produces a visual image called a
thermogram (or heat picture)
•Some cameras infer temperature
based on the amount of radiation
detected
•Thermography is a powerful tool for
machine and building maintenance

5. Thermal Imagers
5
What is Thermography?
•Is Not Infrared Photography
•The Thermal Imager Produces a
Thermal Image
•The Thermographer Analyses the
Image and draws inferences
•Training is an Important part iof
Thermal Imaging

6. Thermal Imagers
6
What is thermography
In nature some of the animals have the
vision of objects in thermal form and not
as normally as we see ! ! !
e.g. a Rattle snake does not see the
world as we normally see it but it sees
the object / its prey thermally.

7. Thermal Imagers
7
History of thermography
This technology was for years
being used for military application
to view objects and infiltrations at
the borders and so on.
Further as the technology flourished
this found applications in Medical
applications to find out problematic
areas in animal & Human bodies.

8. Thermal Imagers
8
•Is the science of seeing heat patterns using special electronic cameras
Rather than seeing light, these remarkable instruments create pictures of
heat. They measure infrared (IR) energy and convert the data to images
corresponding to the temperature.
Thermal imaging Cameras

9. Thermal Imagers
9
Heat and energy
•As an object warms up, it
radiates more energy, as
photons, based on:
–Temperature
–Emissivity
•Infrared radiation is
electromagnetic radiation,
similar to light and radio
waves
•Wavelengths between 2-15
microns are called thermal
infrared radiation

10. Thermal Imagers
10
Heat and Visible light
•When an object reaches
approximately
644C(1200F) visible light is
emitted
•Visible light has shorter
wavelengths that infrared
radiation

11. Thermal Imagers
11
X-rays
Ultra-
violet
Near Infrared
Short Wave
Infrared
Middle
Infrared
Long Wave
Infrared
Microwave
W
a
v
e
le
n
g
t
h

in

M
ic
r
o
n
s

(
µ
m
)
10
-4
10
-2
0.28
0.40
0.70
2.00
6.00
8.00
10
4
15.00
Thermal
The TIs are digital imagers that takes long wave infrared
thermal pictures in the 7.5 to 14 micron range.
The electromagnetic (EM) spectrum is just a
name that scientists give a bunch of types
of radiation when they want to talk about
them as a group.
Infrared radiation, like light
and radio waves, is a form of
electromagnetic energy.
The electromagnetic spectrum

12. Thermal Imagers
12
An Infrared System
Windows
and Optics
Object Environment
Detector
Electronic Display
or Other Output
453¡C
SP1 470¡C
EMS ¯.85
IR Sensor
Collected
IR
Energy
IR
Electronics
S
T

13. Thermal Imagers
13
How do we get the picture?
120 Elements
1
6
0

E
le
m
e
n
t
s
Each of the element or pixels,
contain an accurate temperature
value. The Imager, through the use
of a complex set of algorithms,
assign specific colors that
correspond exactly with the
temperature value found at the
specific X Y coordinate.

14. Thermal Imagers
14
Thermography Interpretation
Higher Temp.Lower Temp.
InfraredInstitute.comInfraredInstitute.comInfraredInstitute.comInfraredInstitute.com
21.8°C
34.7°C
22
24
26
28
30
32
34

15. Thermal Imagers
15
IR Camera
•Lens
•Detector
•Processing
electronics
•Controls
•Image display
•Image storage

16. Thermal Imagers
16
Principles of Heat
transfer •Heat is transferred from
warmer areas to cooler
areas by:
–Conduction (in solids)
–Convection (in fluids)
–Radiation (mainly from
surfaces)
•Heat flow can be either:
–Transient
–Steady-state

17. Thermal Imagers
17
Surface temperature
•Our interest is most often to
understand internal heat sources:
–Abnormal resistance in electrical connections
–Mechanical friction
–Missing or damaged insulation
•What is the relationship between
the surface temperatures we see
and the internal heat source?

18. Thermal Imagers
18
Thermal gradient
•A thermal gradient exists from
the inside to the outside
•The primary factors influencing
this are:
–Conduction
–Thermal capacitance
–Convection
–Load on the system
–Emissivity of the surface
–State change on the surface

19. Thermal Imagers
19
•Is non-contact
•Applies to most types of
equipment and
conditions
•is obtained without
disturbing production
•quickly identifies
specific locations
•allows for detection of
problems before failure
•can scan large areas
quickly to identify areas
of concern
Thermal imaging Benefits

20. Thermal Imagers
20
Emissivity and Blackbodies
Ideal Blackbody “Real Body”
Perfect absorber
and emitter
Some energy is
reflected and transmitted
Emissivity () =1 Emissivity () < 1
I
I
I
I
R
T




I


21. Thermal Imagers
21
Radiometric imaging
• The camera detects
infrared radiation
• The source can be:
–Reflected
–Transmitted
–Emitted
• Only the emitted
radiation tells us about
surface temperature.

22. Thermal Imagers
22
Emissivity
•Emissivity is a material property that describes the efficiency with which an
object radiates or emits heat.
•Emissivity is a value from 0-1.0
–Shiny metals have low emissivity
–Non-metals have high emissivity

23. Thermal Imagers
23
How to set emissivity
•Use emissivity
tables as guidelines
only
Measurements below .6 are unreliable —
even when you set emissivity correction values
•Press F1 or F3 to raise or
lower the emissivity setting.

24. Thermal Imagers
24
Reflected Temperature
Compensation
•Targets that have low emissivities will reflect energy from nearby
objects. This additional reflected energy is added to target’s own
emitted energy and may result in inaccurate readings.
Use the RTC function to compensate for reflected
temperature from emitted energy
In some situations objects near the target
(machines, furnaces, or other heat sources) have a
temperature much higher than that of the target.
And in other cases the reflected temperature may be lower
than the target such as when a clear sky is reflected.

25. Thermal Imagers
25
Thermal Imaging is a surface Technology

26. Thermal Imagers
26
Qualities of a good image
•Focus
•Brightness
•Contrast
•Perspective
•Composition
•Angle of view
A good image should
exhibit all of these attributes

27. Thermal Imagers
27
Qualities of a good IR image
•Focus
•Thermal level
•Thermal span
•Thermal range
•Perspective
•Composition
•Palette

28. Thermal Imagers
28
Focus
•A well focused image provides clarity and depth not
witnessed from an out of focus image.
•Focus is the most important step when capturing a
quality thermal image and cannot be changed after
saving the image.

29. Thermal Imagers
29
Level and Span
•Cameras can be set for “auto” or “manual” rescaling
•Auto rescaling adjusts image to highest and lowest
temp in FOV
•Taking advantage of the manual level and scale
adjustment can give you better thermal resolution
within the FOV

30. Thermal Imagers
30
Level and Span
Manually adjusted
Auto Scaled

31. Thermal Imagers
31
Resolving detail
Resolution defines the ability of the TI
to resolve and measure detail at a
given distance
It is possible to detect objects that are
too far away or too small to accurately
measure.
Just because you can see it doesn’t mean you
can accurately measure its temperature

32. Thermal Imagers
32
Thermal imaging enables service/installer/maintenance
technicians to STOP fighting fires and fix problems before they
result in large-scale losses.
– Find hot spot
– Fix equipment before failure
– Keep equipment operating efficiently
Proactive vs. Reactive

33. Thermal Imagers
33
CONDITION MONITORING
Condition Based Maintenance is the
maintenance initiated as a result of knowledge
of the condition of an item from performing
inspections with condition monitoring
technologies.

34. Thermal Imagers
34
CONDITION MONITORING TECHNIQUES
 
Rotating Equipments Electrical
Stationary Equipments
Equipment to be
Inspected
Chillers Transformers Insulation
Motors Circuit Breakers Tanks
Pumps Capacitors Refractory
Fans High-Voltage Switches Roofs
Generators Motors Steam traps
Compressors Controls Building envelope
Gear Boxes Panels Furnace interiors
  Cables Piping leaks
  Generators Heat exchangers
  
HV Terminations Valves
Inspection
Technology
Thermography Thermography Thermography
Vibration Measurement Oil Analysis Ultrasound
Alignment/balancing Ultrasound Combustion analysis
Oil testing (ferrography) Corona Testing Air flow
Ultrasound Volt/amp Levels Ultrasound
Motor circuit evaluation Power factor test 

35. Thermal Imagers
35
Advantages of a Thermography CM
Program
•Find the problem before it finds you!
•Improved less expensive maintenance
•Consistent and improved availability
•Increase in production rate
•Reduced maintenance costs
•Extend asset life (less need for capitol expenditure)
•Reduce asset base i.e. spare parts
•Increased product quality and consistency.

36. Thermal Imagers
36
Questions?