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Present by: Kausik Das.(0215)
Student of The assam Kaziranga university.

Pyrometers

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Transducers
Classification of Transducers
Application
Advantages & Disadvantages
Errors
Temperature and Heat
Pyrometer
Principle
Types
Advantages and disadvantages
Application
Conclusion

Contents

• Transducers is a device which convert mechanical force
into electrical energy. We can also define transducers as
device which transform energy from one form to
another.
 Example Photo conductor which converts light intensity into a change of
resistance.
 Thermocouple which converts heat energy into electrical energy.

Transducers

Transducers can be classified Primary and secondary
 Active and Passive
 Analog and Digital
 Inverse Transducers

Classification of transducers

 Primary Transducer: The Mechanical device which converts physical
quantity
to
be
measured
into
a
mechanical
signal.
Secondary Transducer: The Electrical device which converts this
mechanical signal to the electrical signal.
 Analog Transducer: These Transducers convert input quantity to an analog
output which is continuous function of time. Ex-Thermocouple or
Thermistor which gives analog output.
Digital Transducers- These converts the input quantity into an electrical
output which is in the form of pulses.
 Passive Transducers: These transducers which require an auxiliary power
source to produce their output. Hence they are also known as externally
power transducers. Ex-Resistive, Capacitive, Inductive.
Active Transducers: These transducers which do not require an auxiliary
power source to produce their output. Ex- Thermocouple, photo voltaic
cells, etc
 Inverse Transducers: These transducers converts an electrical quantity into
a non-electrical quantity. Ex-Piezo electric crystal.

• Antenna – converts propagating electromagnetic waves
to and from conducted electrical signals.
• Loudspeaker, earphone – converts electrical signals into
sound (amplified signal → magnetic field → motion → air
pressure)

Application

• Hydrophone – converts changes in water pressure into
an electrical signal.
• Microphone – converts sound into an electrical signal
(air pressure → motion of conductor/coil → magnetic
field → electrical signal)

Low Current consumption.
Operates in extremely cold temperature.
Power requirement is very low for controlling the
electrical or electronic system.

Advantages & Disadvantages

 The mass inertia effect are minimized.
 Effect of friction are minimized.
 Electrical and electronic system is easily controlled with a
very small power level.
 The
electrical
output
can
easily
be
used, transmitted, processed for the purpose of
measurement.

Advantages of Electrical
Transducers

• Scale Error
•Dynamic error

•Error due to Noise and Drift

Errors in transducers

• A Temperature is a numerical measure of hot or cold. Its
measurement is by detection of heat radiation or particle
velocity or kinetic energy, or by the bulk behavior of
a thermometric material.

Temperature

Heat

Temperature

Definition:

Heat is energy that is
transferred from one
body to another as the
result of a difference in
temperature.

Temperature is
a measure of hotness or
coldness expressed in
terms of any of several
arbitrary scales like
Celsius and Fahrenheit.

Symbol

Q

T

Unit

Joules

Kelvin, Celsius or
Fahrenheit

SI unit:

Joule

Kelvin

Particles:

Heat is a measure of how
many atoms there are in
a substance multiplied by
how much energy each
atom possesses.

Temperature is related to
how fast the atoms
within a substance are
moving.

Ability to do work:

Heat has the ability to do Temperature can only be
work.
used to measure the
degree of heat.

Temperature Vs Heat

Resistance
Thermometer

Thermistor
Thermocouple
and thermopile

Transducers for measuring
temperature

Pyrometer
A pyrometer is a type of thermometer used to
measure high temperatures. It is used for measuring
temperature without any physical contact. Its is used for
measuring body temperature by measuring its
electromagnetic radiation.

• Its principle depends upon the relationship between
temperature of a hot body and electromagnetic
radiation emitted by the body. When a body is heated it
emits thermal energy known as heat radiation. It is a
technique for determining a body temperature by
measuring its electromagnetic radiation.

Principle of Pyrometer

• It is used for high temperature measurement. At high
temperature other transducers such as thermometer may
melt due to direct physical contact but pyrometer can be
used for high temperature measurement without any
physical contact.

Pyrometer Vs other
temperature transducers

Radiation Pyrometer
Optical Pyrometer

Types of pyrometer

• It can measure very high temperatures as no contact
is required.
• They have high output and moderate cost.
• They possess fast response speed.
• It has a good accuracy.
• It is light in weight.

Advantages of Pyrometer

• It requires direct line of sight to the object (or furnace) which
the temperature is to be measured
• It is subjected to emissivity error
• The scale is non-linear
• It is expensive

Disadvantages of Pyrometer

• They can measure temperature above the range of
thermocouple.
• They can be use in the environment where the use of
thermocouple is limited.
• They are used for the target which would be damaged any
contact with primary elements like thermocouples.
• They are used for measurement of Average temperature
of large surface area.

Applications of Pyrometer

If you have any doubt regarding this slide just inform me.
I love to solve it…….thank you.

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Editor's Notes