faculty of engineering & technology , gurukula kangri university , haridwar
DESCRIPTION
Topic:- Tachometer Description :- This is use to measure the speed of rotating machines in rpm.... Ashwini kumar Electrical Engineering [email protected] +919027134556TRANSCRIPT
TACHOMETERSubmitted by:-
ASHWINI KUMARBranch:- Electrical
Class:-B.Tech
Roll no:- 11Roll no:- 11
FACULTY OF ENGINEERING& TECHNOLOGY,GURUKULA KANGRI VISHWAVIDYALAYA
HARIDWARFriday, September 06, 2013
ACKNOWLEDGEMENT
I express my sincere gratitude to ……………………. , Pro. & Head, Department of, faculty of Engineering & technology GuruKula kangri Vishwavidyalaya, for his cooperation and encouragement.
I would also like to thank my seminar guide …………….. , (lecture, Department of EE), for
I would also like to thank my seminar guide …………….. , (lecture, Department of EE), for their invaluable advice and wholehearted cooperation without which this seminar would not have seen the light of day.
Gracious gratitude to all the faculty of the Department of EE & friend for their valuable advice and encouragement.
Friday, September 06, 2013
CERTIFICATEThis is to certify that ASHWINI KUMAR of B.Tech 2nd
year Electrical Engineering student delivered a seminar report on Tachometer.
His Performance in this seminar was excellent / very good/good.good/good.
Guided By
Mr. Kuldeep sir Friday, September 06, 2013
CONTENTS1. Introduction
2. Working principle
3. Types of tachometer
4. Comparison between analog and digital tachometer
5. Classification of tachometer5. Classification of tachometer
6 Digital tachometer
7. Specification of tachometer
8. Block diagram of tachometer
9. Analog tachometer 10. How to choose a tachometer
11. Calibration of tachometerFriday, September 06, 2013
Tachometer, What’s That?
�Tachometer is used for measuring the
rotational speed of machine
�Can be used to measure speed of a
rotating shaft of machinerotating shaft of machine
�Can also be used to measure flow of liquid
by attaching a wheel with inclined vanes
�Can also be used to measure the speed of
car or watchFriday, September 06, 2013
Working Principle�Pules are fed to the tachometer at the
frequency to be measured. A scale factor is
applied to produce readings of desired
types (linear speed, flow rates etc.).types (linear speed, flow rates etc.).
�Tachometer works on two basic principles:-
a) Principle of the fixed time base tachometer
b) Principle of the reciprocal tachometer
Friday, September 06, 2013
Principle of the fixed time base
tachometer
�The tachometer totals the no. of pules receive during fixed period of time known as time base. At the end of this period a value for frequency measured is shown on the display.
� The time base can be set at the time of installation. It is calculated by:-
B =
where:- B = time base
Nt = no. of revolution per minutes
Nd = no. of pules per revolution
V = value appear on display
V x 60Nt x Nd
Friday, September 06, 2013
Principle of the reciprocal
tachometer
�This tachometer measure the interval between
n count pules and then perform the
calculation:-
f = 1
f =
where:- f = frequency
T = no. of intervals
1T
Friday, September 06, 2013
What Are the Different Types of
Tachometer?
�Tachometers can be classified on the basis of
data acquisition – contact or non contact
types
�They can also be classified on the basis of the �They can also be classified on the basis of the
measurement technique – time based or
frequency based technique of measurement
�They can also be classified as analog or digital
type
Friday, September 06, 2013
Comparison Between Analog and
Digital Tachometers
Analog tachometer
�Has a needle and
dial type of interface
�No provision for
Digital tachometer
�Has a LCD or LED
readout
�Memory is provided �No provision for
storage of readings
�Cannot compute
average, deviation,
etc
�Memory is provided
for storage
�Can perform
statistical functions
like averaging, etc
Friday, September 06, 2013
Classification Based on Data
Acquisition Technique
�Contact type – The wheel of the
tachometer needs to be brought into
contact with the rotating objectcontact with the rotating object
�Non Contact type – The
measurement can be made without
having to attach the tachometer to
the rotating object
Friday, September 06, 2013
DIGITAL TACHOMETERSDIGITAL TACHOMETERSDIGITAL TACHOMETERSDIGITAL TACHOMETERSDIGITAL TACHOMETERSDIGITAL TACHOMETERSDIGITAL TACHOMETERSDIGITAL TACHOMETERS
Friday, September 06, 2013
Classification Based on Measurement
Technique
�Time Measurement – The
tachometer calculates speed by
measuring the time interval between measuring the time interval between
the incoming pulses
�Frequency Measurement – The
tachometer calculates speed by
measuring the frequency of the
incoming pulses Friday, September 06, 2013
Comparison Between Time and
Frequency Based Measurement
Time based
� The tachometer calculates speed by measuring the time interval between pulses
� More accurate for low speed
Frequency based
� The tachometer calculates speed by measuring the frequency of pulses
� More accurate for high speed measurement
� More accurate for low speed measurement
� Time to take a reading is dependent on the speed and increases with decrease in speed
� The resolution of the tachometer is independent of the speed of the measurement
measurement
� Time to take a reading is independent of speed of rotation
� The resolution of the tachometer depends on the speed of the rotating shaft
Friday, September 06, 2013
Typical Specifications of a Non Contact
Type Tachometer• Display 5 digits large LCD• Range: 2.5 - 99,999 RPM• Distance: 50 to 1,000 mm; 12 to 40 inches.• Resolution: 0.1 RPM<1000 RPM (2.5
to 9,999 RPM)1.0RPM >1000 RPM
• Measurement angle: at less than 120 • Measurement angle: at less than 120 degrees.
• Range selection: Auto• Laser Output Power: <1mW class II• Sampling Time: 1.0 seconds (over 60 RPM)• Memory: Last value, Max Value, Min. Value• Time base: Quartz crystal• Circuit: Exclusive one-chip LSI circuit• Battery: 4 X 1.5V AA• Weight: 300g/0.65lb• Size: 190 X 72 X 37 mm
Friday, September 06, 2013
Typical Specifications of a Contact Type
Tachometer• Display 5-digit LCD Display• Range selection Automatic range selection• Time Base 4MHz Quartz Crystal• Sampling Time 1 second (>60 rpm); >1
second (10 to 60 rpm)• Accuracy ± (0.1% of reading + 2 digits)• Photo Tachometer Distance 2 to 12” (5 to • Photo Tachometer Distance 2 to 12” (5 to
30cm)• Operating Temperature 32 to 122oF (0 to
50oC)• Operating Humidity 80% RH Max.• Power supply 9V Battery• Battery Life 40 hours (approx.)• Applicable standards EN 50081-1/1992 (EN
55022) EN 50082-1/1997 (EN 55024)• Dimensions 461700: 4.9 x 2.0 x 1.3” (124 x
51 x 33mm)• Weight 461700: 4.0 oz. (114g) Friday, September 06, 2013
Block Diagram of a Digital
Tachometer
Display
Microcontroller
Memory
Optical /
magnetic sensorSignal
conditioning
External
port (to
controller)
Block DiagramFriday, September 06, 2013
Optical Sensing
�It is used to generate pulses proportional to the
speed of the rotating shaft
�Can be achieved by the following ways:
– Attaching a disk, which has an alternate black – Attaching a disk, which has an alternate black
and white pattern, to the shaft and reading
the pulses by a IR module pointed towards it
– Using a slotted disk and a U shaped IR emitter
detector pair to generate waveforms
Friday, September 06, 2013
Magnetic Sensing
• Hall effect sensors – These make use
of the Hall effect to generate pulses
proportional to the speed of the proportional to the speed of the
shaft
• Passive magnetic sensors – These
make use of variable reluctance to
generate pulses
Friday, September 06, 2013
Signal Conditioning
• The output of the sensors may be
noisy
• The output may have to be amplified• The output may have to be amplified
• It has to be digitized. This is done by
Schmitt triggering so as to bring
voltage to TTL levels
Friday, September 06, 2013
Microcontroller
• Not essential, but is generally the norm to have a microcontroller
• Compute the speed
• Can store the readings• Can store the readings
• Can output values to a display unit
• Give out warning signal when speed reduces / increases beyond set margins
• Transfer data to external controller
Friday, September 06, 2013
Display Unit
• Used to output the values to the
operator
• Can be used to view the stored • Can be used to view the stored
values
Friday, September 06, 2013
ANALOG TACHOMETERANALOG TACHOMETER
Friday, September 06, 2013
Analog Tachometers
• These are generally the ones that
display the speed of your car
• The interface is needle and dial • The interface is needle and dial
arrangement
Friday, September 06, 2013
Analog Measurement
Techniques• Generally speed is converted to voltage
through the use of an external frequency to voltage converter
• The tachometer can also act as a generator • The tachometer can also act as a generator and produce a voltage that is proportional to the speed of the shaft
• This voltage is then displayed by an analog voltmeter
Friday, September 06, 2013
How To Choose a
Tachometer?• Accuracy
• Precision
• Range
• Acquisition Time• Acquisition Time
• Contact type / Non Contact type
• Portable / Fixed
• Digital / Analog
• Cost
Friday, September 06, 2013
Calibration
• Why calibrate?
– Wrong calibration = Wrong readings
– Calibration compensates for ageing, wear and tear
and other degrading effectsand other degrading effects
• How to calibrate?
– Calibration is done by comparing the reading from
tachometer to a standard speed
– Necessary changes are made so that the actual
reading matches the desired reading
Friday, September 06, 2013
THANK YOU☺
ASHWINI KUMARASHWINI KUMARASHWINI KUMARASHWINI KUMAR
ELECTRICAL ENGINEERINGELECTRICAL ENGINEERINGELECTRICAL ENGINEERINGELECTRICAL ENGINEERINGELECTRICAL ENGINEERINGELECTRICAL ENGINEERINGELECTRICAL ENGINEERINGELECTRICAL ENGINEERING
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Friday, September 06, 2013