1. Course Code: 2EC307 Review - 2
VRUSHABH SANGHAVI (09BEC115)
DEEP ADHVARYU (09BEC104)
UNDER THE GUIDANCE OF PROF. N. P. GAJJAR
2. What is Energy?
In Physics, energy is an indirectly observed quantity.
When matter is changed into energy (such as energy of
motion, or into radiation), the mass of the system does not
change through the transformation process.
Energy is the capacity of a system to do work.
The total energy contained in an object
cannot be created nor be destroyed in
accordance with the law of conservation
3. What are Sensors?
A sensor is a device that measures a physical quantity
and converts it into a signal which can be read by an
observer or by an instrument.
For accuracy, most sensors are calibrated against
Left: Thermocouple used as Temperature Sensor
4. A good sensor obeys the following rules:
Should be sensitive to the measured property
Should be insensitive to any other property likely to
be encountered in its application
Does not influence the measured property
Ideal sensors should be designed to be linear or linear
to some simple mathematical function of the
6. Factors taken into consideration while designing
Environmental Factors Economic Factors
Temperature Range Cost
Over range protection
Susceptibility to EM
Self test Capability
7. Energy Sensors
Sensor is a device,
which responds to
an input quantity by
output usually in the
form of an electrical
or optical signal.
Above: Pictures Of Energy Sensors
8. Importance Of Energy Sensors
Sensors are pervasive. They are embedded in our bodies,
automobiles, airplanes, mobile phones, chemical plants,
industrial plants and countless other applications.
Sensors are used in everyday objects such as touch-sensitive
elevator buttons (tactile sensor) and lamps which dim or brighten
by touching the base. There are also innumerable applications for
sensors of which most people are never aware. Applications
include cars, machines, aerospace, medicine, manufacturing and
9. Sensors are needed to convert physical data available in
the form of different kinds of energies for analytical and
control purposes into electrical signals.
10. Application Of Sensors
Sensors are used in:
Fire Alarms(in picture)
OTEC (Ocean Thermal Energy Conversion)
Wind Turbine Transmission Monitoring
Wind Turbine Lubrication Systems
11. • Hybrid Engine Testing
• Materials and Component Testing
• Hydraulic Systems Testing
• Handling Systems for Nuclear Fuel Rods
13. Classification Of Energy Sensors
Sensors may be classified according to the various
energies it can detect. They are:-
1. Mechanical Energy Sensors
2. Thermal Energy Sensors
3. Nuclear Energy Sensors
4. Solar Energy Sensors
5. Seismic Energy Sensors
14. Mechanical Energy Sensors
Mechanical Energy Sensors are the sensors that detect a
change in the mechanical energy of the system.
Mechanical quantities: displacement, Strain, rotation
velocity, acceleration, pressure, force/torque, twisting,
Here we will consider sensors for displacement, velocity,
15. Some of the mechanical energy sensors are:
Capacitive Accelerometer for Acceleration Sensing
Piezoelectric accelerometer for Acceleration Sensing
Metal foil strain-gauge based (load cell) for force sensing
LVDT (Linear Variable Differential Transformer)
Scanning Laser Vibratometry for velocity sensing
(a) Capacitive Accelerometer (b) Linear Variable
16. Capacitive accelerometer
SensingAccele Good performance over low frequency
ration Sensing range, can measure gravity!
Heavier (~ 100 g) and bigger size than
Measurement range up to +/- 200 g
More expensive than piezoelectric
Sensitivity typically from 10 – 1000
Capacitive Frequency bandwidth typically from 0
to 800 Hz
Operating temperature: -65 – 120 C
17. Piezoelectric accelerometer
Sensing Nonzero lower cutoff frequency (0.1 –
1 Hz for 5%)
Light, compact size (miniature
accelerometer weighing 0.7 g is
Measurement range up to +/- 500 g
Less expensive than capacitive
Sensitivity typically from 5 – 100
Broad frequency bandwidth (typically
0.2 – 5 kHz)
Operating temperature: -70 – 150 C
18. Metal foil strain-gage based (load cell)
Good in low frequency response
High load rating
Resolution lower than
Rugged, typically big size, heavy
19. Piezoelectricity based (force sensor)
lower cutoff frequency at 0.01 Hz
• can NOT be used for static load
Good in high frequency
Limited operating temperature
Piezoelectric Based (can not be used for high
Compact size, light
20. LVDT (Linear Variable Differential
Sensing Inductance-based electromechanical
limited by external electronics
Limited frequency bandwidth (250 Hz
typical for DC-LVDT, 500 Hz for AC-
No contact between the moving core and
no friction, no wear, very long operating
Accuracy limited mostly by linearity
Linear Variable Models with strokes from mm’s to 1 m
21. Scanning Laser Vibrometry
Sensing No physical contact with the test object;
facilitate remote, mass-loading-free
vibration measurements on targets
measuring velocity (translational or
automated scanning measurements with
fast scanning speed
However, very expensive (> $120K)
22. Thermal Energy Sensors
The Sensor used to detect heat energy is known as
Heat Energy Sensor or Thermal Sensors.
The simplest example of a heat energy sensor is a
thermocouple. It provides a voltage proportional to
the temperature across its junctions.
Sensors Thermistors have negative temperature
2 They are non-metallic made of metallic
Thermal Resistor oxides like manganese, nickel, cobalt or
The electrical resistance of material
change with temperature
They come in different forms:
25. Heat Flux Sensor
A heat flux sensor should measure the local heat flux density in
one direction. The result is expressed in watts per square meter.
The calculation is done according to:
Where Vsen is the sensor output and Esen is the calibration constant,
specific for the sensor.
Heat flux sensors generally have the shape of a flat plate
and a sensitivity in the direction perpendicular to the
26. Heat Flux The total heat flux is composed of a
Sensor conductive, convective and radiative part.
Depending on the application, one might
want to measure all three of these
quantities or single one out. An example of
measurement of conductive heat flux is a
heat flux plate incorporated into a wall.
Heat Flux Plate The gold sensor only measures
convective heat flux, the black sensor
measures radiative as well as convective
heat flux. A small air temperature sensor is
added to estimate local heat transfer
Heat Flux Sensor
27. a sensor sensitive to radiative as well as
convective heat flux is a Gardon or
Schmidt–Boelter gauge, used for studies
of fire and flames.
The Gardon must measure convection
perpendicular to the face of the sensor to
be accurate due to the circular-foil
construction, while the wire-wound
geometry of the Schmidt-Boelter gauge
Gardon or Schmidt can measure both perpendicular and
Boelter gauge showing parallel flows.
the instrument main
28. Nuclear Energy Sensors
Nuclear potential energy is the potential energy of
the particles inside an atomic nucleus.
This category of inventions has tremendous amount
There are a number of sensors or detectors which
were invented lately to detect nuclear potential energy.
sensors are engineered to the highest
standards in performance and reliability.
HVAC claims that it will help improve
facility’s environment while cutting utility
expenses and equipment costs
Radioactive sensors by
31. Solar Energy Sensors
The Solar Radiation Sensor, or solar pyranometer,
measures solar radiation, the sum at the point of
measurement of both the direct and diffuse components
of solar irradiance.
Left: Dual Solar Sensor from GE Electronics Sensing
32. The sensor’s transducer, converts incident
Pyranometer radiation to electrical current, is a silicon
photodiode with wide spectral response.
The transducer is an hermetically-sealed
silicon photodiode; the included amplifier
converts the transducer current into 0 to
33. Sensors from Hukseflux
Hukseflux manufactures and
sells pyranometers (global solar radiation),
pyrheliometers (direct solar radiation) and
albedometers (solar radiation balance)
The most common applications of these
instruments are in measurement of the
available solar energy (for use of solar
radiation as a source of renewable energy),
climatology (for assessing local climate and
Hukseflux energy balance) and building physics.
34. GE Sensors For Cars
The dual solar sensor uses two photo
diode cells inside of it to measure the
intensity of the light that enters into the
cabin of the vehicle. It then takes this
information and feeds it back to the
Dual solar Sensor by GE automatic temperature control (ATC) unit of
the vehicle's air conditioning system. The
air temperatures of the driver's side and
passenger side are then automatically
adjusted up or down depending upon the
amount of light entering both sides of the
35. Light Sensors
A light sensor detects presence of light.
The best example of light sensor is photodiodes.
Thorlabs' C-Series Photodiode Power Meter Sensors cover a
wide power and wavelength range. These sensors are offered
in standard, slim, integrating sphere, and compact fiber
versions to meet your specific application requirements.
36. • Light sensitive variable resistors.
resistors • Its resistance depends on the intensity of
light incident upon it.
– Under dark condition, resistance is
quite high (MΩ: called dark resistance).
– Under bright condition, resistance is
lowered (few hundred Ω).
• Response time:
– When a photo resistor is exposed to
light, it takes a few milliseconds, before
it lowers its resistance.
Photoresistors – When a photo resistor experiences
removal of light, it may take a few
seconds to return to its dark resistance.
37. Photo resistors exhibit a nonlinear
Resistors characteristics for incident optical
illumination versus the resulting
log10 R = α − β log10 P
101 102 103 104
Relative illumination (P)
38. Seismic Energy Sensors
Seismic Sensors have shown their applicability to target
bearing, range, and classification problems in the battlefield
monitoring and perimeter defense system.
This kind of sensor can perform accurate measurements of
small ground vibration and monitor seismic activity due to
their high sensitivity to dynamic strains induced by
Seismometers and Accelerometers are available for this
39. Seismic Sensors by HP and Shell
Hewlett-Packard Co. and Shell announced
that they are developing a new wireless
sensing system for acquiring high-resolution
Improved and increasingly powerful
computer technology has over the years
Microelectromechan enabled the seismic images to become
increasingly precise, with the possibility of
deploying thousands of sound detectors,
often in a grid pattern that enables
geophysicists to build a three-dimensional
image of the subsurface
40. Fiber Bragg grating sensors for
seismic wave detection
seismic sensors based on the optical
fiber Bragg grating. This kind of sensor
can perform accurate measurements of
the seismic activity due to their high
sensitivity to dynamic strains caused by
small ground vibrations.
Light weight and compact
125 micro centimeter in diameter
41. Seismic wave detection system based
Seismic on fiber optic sensor
Optical fiber sensors using fiber Bragg
grating have a number of advantages such
as immune to electromagnetic interference,
lightweight, and low power consumption.
The basic principle of the FBG seismic
sensing system is that it transforms the
acceleration of ground motion into the strain
signal of the FBG sensor through
mechanical design, and after the optical
demodulation generates the analog voltage
output proportional to the strain changes.