Chauvin Arnoux 1875 User manual

GB – User’s Manual
Thermography bench
C.A 1875

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You have just purchased a C.A 1875 thermography tutorial bench and we thank
you for your confidence.
For best results from your instrument:
•read these operating instructions carefully,
•observe the precautions for use
MEANINGS OF THE SYMBOLS USED
Selective sorting of wastes for the recycling of electrical
and electronic equipment within the European Union.
In accordance with directive WEEE 2002/96/EC: this
equipment must not be processed as household waste.
Possible hazard. Refer to the operating instructions before
using the device.
The CE marking guarantees conformity with European
directives and with regulations concerning EMC.
Attention, hot surface
PRECAUTIONS FOR USE
If this device is damaged or a part is missing, please immediately contact the seller.
Non-observance of the instructions or of the precautions for use may impair the
protection provided by the device.
Refer to these instructions concerning each danger symbol encountered.

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CONTENTS
1. INTRODUCTION ...............................................................................................4
2. PRESENTATION ...............................................................................................5
3. CHARACTERISTICS ...........................................................................................7
3.1 GENERAL CHARACTERISTICS OF THE BENCH ........................................................ 7
3.2 CHARACTERISTICS OF THE FUSE........................................................................ 8
4. COMMISSIONING ............................................................................................8
5. MANIPULATIONS ............................................................................................9
5.1 THERMAL TRANSFERS.............................................................................. 9
5.1.1 Theory.............................................................................................. 9
5.1.2 Manipulations: study of the influence of emissivity ...................... 15
5.2 STUDY OF THE REAL BODY............................................................................. 16
5.2.1 Theory............................................................................................ 16
5.2.2 Manipulations: study of the influence of reflection and transmission
....................................................................................................... 18
5.3 OPTICS AND THERMOGRAPHY CAMERA................................................ 18
5.3.1 Theory: study of the spatial resolution. ......................................... 18
5.3.2 Manipulation: study of spatial resolution...................................... 22
5.4 MANIPULATIONS ON SOFTWARE .......................................................... 23
5.5 THERMOGRAPHY IN PRACTICE .............................................................. 25
5.5.1 Fault determination modes. .......................................................... 25
5.5.2 Applications ................................................................................... 26
5.6 PRODUCING A Q19 REPORT .......................................................................... 28
5.6.1 Presentation .................................................................................. 28
5.6.2 Application..................................................................................... 31
6. MAINTENANCE..............................................................................................31
6.1 REPAIR ..................................................................................................... 31
6.2 CHANGE OF FUSE ................................................................................... 32
7. WARRANTY ...................................................................................................32
8. TO ORDER .....................................................................................................32
APPENDIX 1: DETERMINATION OF EMISSIVITY..................................................33
APPENDIX 2: DETERMINATION OF REFLECTED TEMPERATURE..........................34
APPENDIX 3: APPLICATION EXERCISES ..............................................................35
APPENDIX 4: SOLUTIONS ..................................................................................41

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1. INTRODUCTION
Infrared thermography detection technology has become an essential means of
guaranteeing the safety of industrial production conditions. It is used in sectors of
industry as varied as metallurgy and steel-making, electric power, the oil industry,
automation, the extraction of natural gas, the transport industry, and other
professions active in fire fighting and border surveillance. In all of these activities,
characterized by just-in-time operating procedures, production equipment at high
voltage, powerful electric currents, or high operating speeds, infrared thermal
imaging can be a useful contact-free real-time inspection method.
This detection method requires no breaking of current, no stopping of machines or
interruption of production. It can diagnose latent defects in advance, and so
forestall the occurrence of malfunctions and prevent production incidents. Thermal
imaging is an innovative "contact-free" evaluation technique that is all at once safe,
reliable, and rapid.
A thermal camera does not measure temperatures, but radiant fluxes. After the
adjustment of a few parameters by the thermography operator, the camera
calculates the temperatures of the target. It then gives the user a map of the
temperatures, or "thermogram": each temperature is represented by a colour.
Here are two examples of thermograms:
Inside views of three-phase electrical boxes
First of all, we can see that these two thermograms are practically identical: we
observe one phase that is hotter than the other two (the one on the left in the left-
hand thermogram, the top one in the right-hand thermogram). As it happens, their
colour is light yellow, which indicates according to the colour scale to the right of
the IR image that the temperature is higher there.
Let's take a closer look at these two images, by inserting temperature cursors.
Left-hand thermogram:
-Cursor 1: 52.9°C
-Cursor 2: 44.9°C

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In accordance with the rules of classical thermography (see below), there is no
particular problem.
Right-hand thermogram:
-Cursor 1: 60.3°C
-Cursor 2: 35.3°C
In this case, the temperature difference is 25°C! We can conclude that there is a
real problem in the installation and corrective action must be taken.
In conclusion, it is necessary to pay attention to the colour scales and to perform a
genuine analysis. Dark means colder and light means hotter, but that does not
mean that there is a problem to be detected! Bear in mind that the camera is a
measurement tool and that the investigations must be continued!
2. PRESENTATION
Growing demand for training in infrared thermography has led CHAUVIN ARNOUX
to develop measurement equipment specially designed for instructional purposes.
Far from being exhaustive, the manipulations proposed are intended only to
illustrate, through a few examples, the false measurement records it is possible to
produce in infrared thermography.
The objective is to make people aware that an infrared camera is a precision
measurement tool that requires much training and experience to use correctly.
The C.A 1875 tutorial bench comprises a hot plate with several targets having
different surface conditions and made of different materials, along with test screens
that are affixed to the front of the bench using magnets. (See the diagram below).
The purpose of this bench is to allow the student to discover the main possible
causes of error when making a measurement using an infrared camera.
This equipment can be used to perform the following experiments:
-Problem of emissivity of the materials
-Problems of positioning
-Problem of reflection
-Problem of transmission
-Problem of spatial resolution

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Presentation of the C.A 1875 thermography tutorial bench:
1: Hot plate
2: LEDs indicating rising or falling temperature
3: On / Off switch
4: Power cord connection
5: Fuse compartment
6: 10: Plates of different materials
7: Cover protecting the bench
8: Test screen attachment plate
9: Black reference plate for the various tests
10
9
8
7
6
5
4
3
2
1

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Presentation of the test screens
Test screen no. 1:
Plexiglas pane
Presentation of the hot targets
3. CHARACTERISTICS
3.1 GENERAL CHARACTERISTICS OF THE BENCH
Power supply: 230 V
50 / 60 Hz
Consumption: 400 mA
Temperature of hot plate: 50 to 55°C ±3°C
Dimensions: 280 x 225 x 110 mm
Weight: 1.8 kg
Black plate having an
emissivity of 0.95
Plate 6:
Aluminium
Plate 4:
Red copper
Plate 3:
Laminate
Plate 2:
Stainless steel
Plate 1:
Polish steel
Test screen no. 2:
Slits of variable width
Plate 5:
Brass

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Environmental conditions:
Indoor use:
0 to 40°C and 10 to 90% RH
Altitude less than 2000 m
Degree of pollution 2
Storage:
-20 to + 65°C and 10 to 90% RH
Altitude less than 12,000 m.
NB: storage at a higher temperature is possible but requires manually resetting the
safety thermostat to render the device functional.
Conformity to international standards:
- Safety as per IEC 61010
- EMC as per IEC 61326-1
3.2 CHARACTERISTICS OF THE FUSE
Dimensions: 5 x 20 mm
Rating: 0.5 A fast-blow – 250 V
4. COMMISSIONING
The C.A 1875 thermography tutorial bench must be placed on a flat, level
surface. The hot plate must be perpendicular to the work top.
Once the bench is in place, connect it to a mains outlet with an earth and power up
using the On/Off button.
Wait a few minutes for the plate to warm up before running the first tests.

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Diagram of operation of the LEDs and of the temperature variation of the hot plate.
When the bench is started up, L1 lights until the plate reaches approximately 55°C.
When this temperature is reached, L2 lights and the plate cools to approximately
50°C. Heating resumes, with the lighting of L1, and so on. This cycle continues
indefinitely for as long as the bench is in operation.
5. MANIPULATIONS
Look up the operating instructions for the use of the RayCAm.
Before any new manipulation, create a new thermogram recording folder.
During the manipulations, save as many images as possible.
5.1 THERMAL TRANSFERS
5.1.1 Theory
To correctly understand the events involved, it is important to know the phenomena
that underlie evolutions or changes of temperature.
There are three thermal transfer modes:
-Conduction
-Convection
-Radiation
These three modes can be present simultaneously, independently of one another.
A heat flux is a quantity of thermal energy per unit of time. A transfer flow occurs
only when there is a temperature difference. Thermal energy is transferred from a
hot body to a cold body.
It is necessary first of all to understand the thermal phenomena involved.
L1 L2
T(°C)
Ta
Regulation
t
60° Max

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Conduction.
In physics, thermal conductivity is the parameter used to quantify the ability of a
body to conduct heat. It represents the quantity of heat transferred per unit of area
and per unit of time under the action of a temperature difference between the two
ends of a sample of the body, and therefore in the presence of a temperature
gradient.
Consider the example of a metal bar that is heated at one of its ends: the thermal
agitation of the atoms located at the heated end of the bar increases and is
transmitted step by step in the direction opposite the thermal gradient.
Application: see Appendix 3, exercise 1
Convection.
A flow or circulation of a liquid or gas can transport with it a certain quantity of
thermal energy. This transport of heat is called thermal CONVECTION. In
convection, the heat uses the fluid as a vehicle to convey it. There are two types of
convective transfers:
-Natural convection: when there is a temperature difference between two
points in a fluid, the hot fluid tends to rise because of its buoyancy. This
creates a natural circulation of the fluid under the effect of the heat, which
is then transported by it: this is called natural convection.
Thermal gradient
Temperature rise at the end of the bar

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-Forced convection in which the flow of the fluid is forced by some
mechanical device (pump or gravity for a liquid, blower for air).
Forced convection is an undesirable phenomenon in infrared thermography. This is
because forced convection cools the surface of a body without for all that altering
its internal temperature.
For example, wind is a vector of forced convection. When there is wind, people feel
cooler and their skin temperature may fall. But their internal temperature will not be
modified at all! With or without wind, human body has a very fine regulation of its
temperature.
Since we measure only the surface temperatures of objects in thermography, our
analysis will be wrong. This is because the surface of the material will be at a
uniform temperature because of forced convection, but the internal temperatures
may be different.
Application: see Appendix 3, exercise 2

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Radiation: case of the full radiator or black body.
Anybody at a temperature above 0 degree kelvin (absolute zero, or -273.15°C)
emits electromagnetic radiation called thermal radiation. Infrared radiation is
electromagnetic radiation of which the wavelength is between 700 nanometres and
1 millimetre.
Given the law of the conservation of energy, for a body to radiate, it must be the
source of the energy: this is an internal energy.
In thermography, the radiation is used to measure the temperature of the body.
For each given temperature and wavelength, there is a maximum radiated energy
that nobody can exceed. This information is provided by Planck's curves:
Wien's law gives the wavelength (in micrometers) corresponding to the maximum
radiated energy of a black body at a specified temperature T (in Kelvin).
2898
λmax=
T
The wavelength of the infrared radiation maximum decreases as the temperature of
the black body increases.
Radiated
energy

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The Stefan-Boltzmann law is used to quantify these exchanges. The energy E
radiated by a body is written:
E = S. σ. T4
With:
E: radiated energy expressed in W/m².
σ: Stefan-Boltzmann constant = 5.6703 x 10-8 W.m-2.K-4
S: area of the body expressed in m²
T: temperature of the body in Kelvin
A black body is a body of which the surface absorbs all radiation received.
NB: a black body is not a real thing, but an idealized object from which the only
outgoing radiation is thermal radiation, determined solely by the body's own
temperature.
Application: see appendix 3, exercises 3 and 4
Emissivity
The emissivity of a material (often written ε), is the ratio of the energy it radiates to
the energy a black body would radiate at the same temperature. It is therefore a
measure of the capacity of a body to absorb and re-emit radiant energy.
The emissivity is a quantity between 0 and 1.
The laws stated earlier are not strictly true without qualification, making it necessary
to introduce this parameter, the emissivity.
Planck's curve above then becomes:
Radiated
energy
λ (μm)
Curve for a black body at temperature T
Curve for a real body at temperature T

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The lower the emissivity, the lower the maximum of the curve.
The Stefan-Boltzmann law then becomes:
E = ε. S. σ. T4
The emissivity of a material is a characteristic of that material and of its surface
condition. The more capable a body is of absorbing heat, the closer its emissivity to
1. There are nomographs indicating the emissivities of various materials.
To make valid measurements in thermography, it is necessary to perform
manipulations on bodies having a high emissivity (ε > 0.8). This applies to opaque
plastics, oxidized metals, wood and building materials, paints, etc. If a user must
make measurements on materials having a low emissivity, we recommend first
applying black paint to them, then performing the manipulation. Very large
measurement errors can result from neglecting or misjudging this parameter.
Another parameter that influences the emissivity is the measurement angle.
According to the graph below:
Thus, to make a valid measurement, it is necessary to place the camera
perpendicular to the measurement target (facing it squarely) so that the emissivity
entering the camera reflects reality. A tolerance of +/- 45° is accepted.
The emissivity is a fundamental parameter in thermography. It is essential to set it
correctly before making any measurement. For this purpose, it is enough to know
the material of which the temperature is to be determined and enter the
corresponding emissivity in the camera.
If no information is available about the type of the body concerned, there is a
standard that specifies how to determine this parameter (See Appendix 1).

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5.1.2 Manipulations: study of the influence of emissivity
Manipulation 1: Highlighting the problems of measurement on materials having
different emissivities.
Make sure that the temperature of the bench has been stable for a few moments.
Aim the camera at the hot plate, making sure that you are correctly positioned in
front of the bench.
- The field of view of the camera must include the central plate and at least one of
the 6 outer plates.
Is this the case?
What conclusion can you draw?
- Using the technique for determining emissivity described in appendix 1, determine
the emissivities of the various plates.
- Place a piece of black adhesive tape on one of the 6 outer plates. Aim the camera
at this plate again.
What do you observe?
What conclusion can you draw?
Manipulation 2: Highlighting the problems of positioning with respect to the target.
Create a new folder.
- Aim the camera at the hot plate, making sure that you are correctly positioned
perpendicular to the bench. Target the black zone in the centre, which has a high
emissivity, close to 0.95.
- Make a temperature measurement at the centre of the plate.
- Tilt your camera slightly. Make another temperature measurement.
- Repeat the operation, tilting your camera again, by approximately 10° each time,
and record the temperature.
What conclusion can you draw?

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5.2 STUDY OF THE REAL BODY
5.2.1 Theory
The black body is a theoretical object. The formulas given above can be
applied to a real object only with a few corrections: real objects absorb only a
fraction α of the incident radiation, reflecting a part ρ and transmitting a fraction τ.
The principle of the conservation of energy yields the following equation:
α. I(T) + ρ. I(T) + τ. I(T) = I(T) ,
or α + ρ + τ = 1
At equilibrium, the object emits ε (T) the same quantity of energy as it absorbs α (T).
This gives the following equation:
α . I(T) = ε . I(T)
or α = ε
Whence:
ε + ρ + τ = 1
In thermography, it is possible to make measurements only on opaque bodies. The
transmission of the materials is therefore zero.
This gives the equation:
ε + ρ = 1
and ρ = 1 - ε
Thus, when making a measurement by thermography, it is necessary to make
allowance for reflected "ambient" radiation. A real measurement situation is
therefore:
Incident radiation at temperature
T: I(T)
ρ (T)
τ (T)
α (T)

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And the total radiation received by the camera is therefore:
Rmeasured = Robject + Rreflected
ε. σ. (Tobject)4 ρ . σ. (Treflected)4
Whence:
Rmeasured = ε. σ. (Tobject)4 + ρ . σ. (Treflected)4
= ε. σ. (Tobject)4 + (1 – ε) . σ. (Treflected)4
To obtain the temperature of the object, it is therefore necessary to enter the
emissivity and reflected temperature parameters in the RayCAm.
The reflected temperature corresponds to the ambient temperature near the target.
If nothing interferes with the target to be inspected, this temperature corresponds to
the ambient temperature.
If a hot or cold source near the target gives off heat, there is a standard that
specifies how to determine the resulting reflected temperature (See Appendix 2).
Application: see appendix 3, exercise 5
Reflected radiation of the
environment on the object
Radiation of the object

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5.2.2 Manipulations: study of the influence of reflection and
transmission
Manipulation 3: Highlighting of the problems of measurement linked to reflection
phenomena
Create a new folder.
- Position the camera in front of the aluminium plate: shiny, having a low emissivity,
and therefore strongly reflecting.
- Make a measurement with your body in front of the plate.
- Make a measurement with your body shifted so as to be no longer in front of the
plate.
- What conclusion can you draw?
Manipulation 4: Highlighting of the problems of measurement linked to problems of
transmission.
Create a new folder.
- Make a temperature measurement on the black plate in the centre, the emissivity
of which is 0.95.
- Place test screen number 1 (plexiglas window) on the zone provided for it on the
bench.
Wait 2-3 minutes for the temperature of the environment to become uniform.
Target the black plate through the plexiglas pane and make a temperature
measurement. Remove the pane and take a measurement one more time.
- What conclusion can you draw?
5.3 OPTICS AND THERMOGRAPHY CAMERA
5.3.1 Theory: study of the spatial resolution.
Observation Spatial Resolving Power (PRSO).
The Observation Spatial Resolving Power (PRSO) can be defined by an angle. It is
known as the IFOV (Instantaneous Field Of View) angle, and is the angle at which
a detector of the matrix sees an elementary surface (Δs) of the thermal scene.
The difficulty in defining IFOV lies in the fact that the dimensions of the matrix
sensors are not standardized. So an objective is designated not by its focal length,
but by the FOV (Field Of View) angle at which the camera sees the thermal scene.
There are in fact two FOVs:

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-HFOV: horizontal angle
-VFOV: vertical angle
Starting from this, IFOV can be defined by the equation:
HFOV VFOV
IFOV (°) = =
ndH ndV
With:
-ndH: number of detectors on the horizontal of the matrix
-ndV: number of detectors on the vertical of the matrix
In practice, the IFOV is generally expressed at milliradians (mrad), which
corresponds to an elementary surface in mm seen at a distance of 1 m
(…mm@1m).
Whence the equation:
HFOV x π x 1000 VFOV x π x 1000
IFOV (mrad) = = = PRSO
ndH x 180° ndV x 180°
The IFOV corresponds to the spatial resolution of the camera, i.e. to the dimension
of the zone a detector can measure. This dimension depends on the camera's
distance from the target.
The closer the camera to the zone to be inspected, the smaller the IFOV and the
smaller the objects the camera perceives.

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Diagram summing up the various concepts:
Application: see appendix 3, exercise 6.
Measurement Spatial Resolving Power (PRSM).
For temperature measurements, as opposed to thermal imaging, it is necessary to
consider the metrological character of the camera.
This is because each detector is independent and makes a measurement of the
radiation received over the whole of its zone. The detector determines the mean of
the total radiation received and indicates the corresponding temperature to the
user.
Consider the case of determining the temperature of a wire.
square Δs
(seen by a
square detector)
Rectangular thermal view
(seen by the rectangular matrix)
IFOV
HFOV
VFOV