A synchronous motor is electrically identical with an alternator or AC generator.
A given alternator ( or synchronous machine) can be used as a motor, when driven electrically.
Some characteristic features of a synchronous motor are as follows:
1. It runs either at synchronous speed or not at all i.e. while running it maintains a constant speed. The only way to change its speed is to vary the supply frequency (because NS=120f/P).
2. It is not inherently self-starting. It has to be run up to synchronous (or near synchronous) speed by some means, before it can be synchronized to the supply.
3. It is capable of being operated under a wide range of power factors, both lagging and leading. Hence, it can be used for power correction purposes, in addition to supplying torque to drive loads.
SYNCHRONOUS MOTOR STARTING METHODS, START करने के METHODS|DAMPER WINDING, AUX...Prasant Kumar
#YOUTUBE_LINK
https://youtu.be/sKrjXF5XfG0
# SYNCHRONOUS_MOTOR_STARTING_METHODS
#DAMPER_WINDING
#PONY_MOTOR
#SYNCHRONOUS_MOTOR_START करने के_METHODS
#STARTING_METHODS_OF_SYNCHRONOUS_MOTOR
#SYNCHRONOUS_MACHINE
#WHY_SYNCHRONOUS_MOTOR_IS_ NOT_SELF_ START
#AUXILLARY_MOTOR
#SAI_ACADEMY_OF_ELECTRICAL_ENGINEERING
#SAEE
#AJBROTHERS
#SIMPLE TRICK OF ELECTRICAL MACHINE
#ANIMATION
#SYNCHRONOUS_MOTOR_SELF_START क्यों नहीं होता है?
#STARTING_SYNCHRONOUS MOTOR
#WHY_SYNCHRONOUS_MOTOR_IS_NOT_SELF_START
#why synchronous motor is not self starting in hindi
#STARTING OF SYNCHRONOUS MOTOR
#SYNCHRONOUS MACHINE
#ELECTRICAL MACHINE
#BASIC ELECTRICAL ENGINEERING
#SAI ACADEMY OF ELECTRICAL ENGINEERING
#SYNCHRONOUS MOTOR FEATURRES
#SYNCHRONOUS CONDENSOR
#POWER FACTOR IMPROVEMENT BY SYNCHRONOUS MOTOR
The motor which runs at synchronous speed is known as the synchronous motor. The synchronous speed is the constant speed at which the motor generates the electromotive force. The synchronous motor is used for converting the electrical energy into mechanical energy.
he stator and rotor are the two main parts of the synchronous motor. The stator is the stationary part, and the rotor is the rotating part of the machine. The three-phase AC supply is given to the stator of the motor.
This presentation provides information about Synchronous Motor.
A synchronous motor is electrically identical with an alternator or AC generator.
A given alternator ( or synchronous machine) can be used as a motor, when driven electrically.
Some characteristic features of a synchronous motor are as follows:
1. It runs either at synchronous speed or not at all i.e. while running it maintains a constant speed. The only way to change its speed is to vary the supply frequency (because NS=120f/P).
2. It is not inherently self-starting. It has to be run up to synchronous (or near synchronous) speed by some means, before it can be synchronized to the supply.
3. It is capable of being operated under a wide range of power factors, both lagging and leading. Hence, it can be used for power correction purposes, in addition to supplying torque to drive loads.
SYNCHRONOUS MOTOR STARTING METHODS, START करने के METHODS|DAMPER WINDING, AUX...Prasant Kumar
#YOUTUBE_LINK
https://youtu.be/sKrjXF5XfG0
# SYNCHRONOUS_MOTOR_STARTING_METHODS
#DAMPER_WINDING
#PONY_MOTOR
#SYNCHRONOUS_MOTOR_START करने के_METHODS
#STARTING_METHODS_OF_SYNCHRONOUS_MOTOR
#SYNCHRONOUS_MACHINE
#WHY_SYNCHRONOUS_MOTOR_IS_ NOT_SELF_ START
#AUXILLARY_MOTOR
#SAI_ACADEMY_OF_ELECTRICAL_ENGINEERING
#SAEE
#AJBROTHERS
#SIMPLE TRICK OF ELECTRICAL MACHINE
#ANIMATION
#SYNCHRONOUS_MOTOR_SELF_START क्यों नहीं होता है?
#STARTING_SYNCHRONOUS MOTOR
#WHY_SYNCHRONOUS_MOTOR_IS_NOT_SELF_START
#why synchronous motor is not self starting in hindi
#STARTING OF SYNCHRONOUS MOTOR
#SYNCHRONOUS MACHINE
#ELECTRICAL MACHINE
#BASIC ELECTRICAL ENGINEERING
#SAI ACADEMY OF ELECTRICAL ENGINEERING
#SYNCHRONOUS MOTOR FEATURRES
#SYNCHRONOUS CONDENSOR
#POWER FACTOR IMPROVEMENT BY SYNCHRONOUS MOTOR
The motor which runs at synchronous speed is known as the synchronous motor. The synchronous speed is the constant speed at which the motor generates the electromotive force. The synchronous motor is used for converting the electrical energy into mechanical energy.
he stator and rotor are the two main parts of the synchronous motor. The stator is the stationary part, and the rotor is the rotating part of the machine. The three-phase AC supply is given to the stator of the motor.
This presentation provides information about Synchronous Motor.
VTU Notes for Testing and commissioning of Electrical Equipment Department of Electrical and Electronics Faculty Name: Mrs Veena Bhat Designation: Assistant Professor SDM Institute of Technology Subject: Testing and Commissioning of Electrical equipment Semester: VII
VTU Notes for Testing and commissioning of Electrical Equipment Department of Electrical and Electronics Faculty Name: Mrs Veena Bhat Designation: Assistant Professor SDM Institute of Technology Subject: Testing and Commissioning of Electrical equipment Semester: VII
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This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Palestine last event orientationfvgnh .pptxRaedMohamed3
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The Roman Empire A Historical Colossus.pdfkaushalkr1407
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Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
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Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
Eet3082 binod kumar sahu lecture_29
1. Electrical Machines-II
6th Semester, EE and EEE
By
Dr. Binod Kumar Sahu
Associate Professor, Electrical Engg.
Siksha ‘O’ Anusandhan, Deemed to be University,
Bhubaneswar, Odisha, India
Lecture-29
2. 2
Learning Outcomes: - (Previous Lecture_28)
To understand the basics of Synchronous Motor.
To know the working principle of poly-phase Induction Motor for its
performance comparison with Synchronous Motor.
3. 3
Learning Outcomes: - (Today’s Lecture_29)
Working Principle of Synchronous Motor.
To understand various methods of starting a Synchronous Motor.
4. 4
Working Principle of Synchronous Motor (Contd...): -
We have already discussed the various features of three-phase synchronous machine. It has a
three phase armature winding generally placed in stator and a field winding kept in the rotor.
In alternator, the synchronous machine receives mechanical power input from its prime
mover and a DC electrical input for field excitation. The mechanical energy is converted
into electrical energy. So alternator can also be called as a synchronous generator.
When the armature winding of the synchronous machine is connected to a 3-phase AC
supply and its field winding to a DC supply, the 3-phase AC electrical input is converted
into mechanical energy and the machine is said to be running as a synchronous motor.
Synchronous motor converts electrical energy into mechanical energy running at
synchronous speed irrespective of the loading condition.
The motor speed varies momentarily only at the instant of load variation.
5. 5
Working Principle of Synchronous Motor (Contd...): -
Synchronous motor works on the principle of the magnetic locking.
When two, unlike poles, are brought near each other, if the magnets are strong, there
exists a tremendous force of attraction between those two poles. In such condition, the
two magnets are said to be magnetically locked.
If now one of the two magnets is rotated, the other also rotates in the same direction
with the same speed due to the force of attraction i.e. due to magnetic locking.
When the stator/armature winding of the synchronous motor is connected to a 3-phase
supply, the current through the 3-phase winding stator winding produces a rotating
magnetic field which rotates at synchronous speed.
120 2
,s s
f f
N rpmor n rps
P P
6. 6
Working Principle of Synchronous Motor (Contd...) : -
Figure 1: Torque produced is clockwise. Figure 2: Torque produced is anticlockwise.
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.
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.
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R1
Y2B2
Y1
B1
R2
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ir
iy
ib
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N1
S2
S1
N2
X
X
.
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...
R1
R2
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Y2
X
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B2
.
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.
XX
.
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ir
iy
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7. 7
Working Principle of Synchronous Motor (Contd...): -
So, for the 2-pole machine, with 50 Hz supply, the speed of the rotating magnetic field
will be 3000 rpm or 50 rps. This effect is similar to the physical rotation of two poles
(N1 & S1) with a speed of 3000 rpm.
When the field winding on the rotor is excited with DC supply, it also produces two
poles (N2 & S2) which are stationary.
In figure-1, north pole of rotor (N2) is attracted by the south pole of stator (S1) and
south pole of rotor (S2) is attracted by the north pole of the stator (N1). So, the
electromagnetic torque is developed in clockwise direction.
8. 8
But within a small time interval (half of the time period) i.e. 10 msec or 0.01 sec, (for 50 Hz
supply) the stator poles (N1 & S1) will rotate by 1800 electrical i.e. they interchange their
positions, as the direction of current through stator coil automatically get reversed.
Due to inertia, before rotor hardly rotates in
clockwise direction, the stator poles change
their positions as shown in figure 2.
Now, the north pole of the rotor (N2) is
repelled by the north pole of the stator (N1),
and south pole of the rotor (S2) is repelled by
south pole of the stator (S1). So, the rotor
experiences a torque in anticlockwise
direction which is opposite to that in figure 1.
9. 9
So, the net torque exerted on the rotor is zero. Due to this, the synchronous motor cannot start
on its own.
Practically it is not possible for stator poles to pull the rotor poles from their stationary position
into magnetic locking condition.
This is because the speed with which rotating magnetic field is rotating, is so high that it is
unable to rotate the rotor from its initial position, due to the inertia of the rotor.
Therefore, a synchronous motor is not self starting.
So, to develop unidirectional torque, before connecting the field winding to a DC source, the
rotor must be rotated at synchronous speed or near synchronous by some means, so that the
relative velocity between the synchronously rotating stator field and rotor is zero.
Since, both rotor and stator field now are stationary with respect to each other, DC excitation
to field winding creates rotor poles which magnetically interlocks the stator poles.
11. 11
Different methods of starting a Synchronous Motor: -
We have seen that synchronous motors are not self starting. Before exciting it’s field
system, the rotor must be rotated at or nearer to synchronous speed by some means.
This can be accomplished by the following three methods:
i. Auxiliary motor starting (using pony motors): - Suitable for no load or light
load.
ii. Induction motor starting (using damper winding): - Suitable for no load or light
load.
iii. Synchronous induction motor starting: - Suitable for starting even with full load
condition.
12. 12
(i) Auxiliary Motor Starting: -
The purpose of the auxiliary motor is to bring the synchronous motor speed, near to its
synchronous speed. The auxiliary motor may be an Induction motor or a DC motor.
After bringing the main motor speed almost equal to its synchronous speed, the armature
winding of synchronous motor is also energised from 3-phase supply.
Now, when the field winding of synchronous motor is connected to DC source, the field
poles get magnetically locked with those produced by armature winding. As a result of this,
main motor starts running as a synchronous motor at synchronous speed.
Auxiliary motor (Induction motor/DC motor) can now be disconnected from three-phase
supply/DC supply or isolated from the main motor.
13. 13
Sometimes an induction motor with two poles, fewer than the synchronous-motor poles, is
used as an auxiliary motor. This induction motor runs the main motor above or equal to its
synchronous speed. After this, the induction motor is switched off and the synchronous
motor armature is switched on to 3-phase AC supply and field winding is energised from DC
supply.
If the main synchronous motor has 12 poles its synchronous speed is (120 x f)/P = 6000/12
= 500 rpm. If the auxiliary motor (induction motor) has also 12 poles, it cannot rotate the
synchronous motor at 500 rpm as induction motor always runs at a speed less than
synchronous speed.
So, if we take an auxiliary motor (induction) motor having 12-2 = 10 poles, its synchronous
speed will be 600 rpm. So this induction motor can run at a speed less than 600 rpm i.e. at
500 rpm which is the synchronous speed of the synchronous motor having 10 poles.
14. 14
If the synchronous motor is coupled with a DC machine, then dc machine is first run as a
DC motor. The main motor, now made to operate as a synchronous generator, is
synchronized with the 3-phase supply system.
If the DC motor is now switched off, the main motor starts running as a synchronous motor.
The disadvantage of this method of starting is that the motor can’t be started under load; in
case it is desired to do so, the auxiliary-motor rating has to be larger, thus increasing the
cost of the set. In view of this, the auxiliary-motor starting is used only for unloaded
synchronous motors.
Note: - During starting, the field winding of the synchronous motor is shorted by means of an
external resistance. Current through the field winding produces an additional torque just like in
induction motor, which helps the rotor to accelerate at a faster rate.
17. 17
(ii) Induction Motor Starting: -
In order to make the motor a self-starting synchronous motor, the amortisseur or
damper winding is embedded in the slots in the rotor pole faces. This winding is short-
circuited at both ends by metal rings. Thus the damper winding is exactly similar to the
squirrel cage winding of a 3-phase induction motors.
When armature is excited from 3-phase supply, a rotating magnetic field is established.
This rotating field and the damper winding develop induction motor torque, and rotor is
therefore, accelerated up to about synchronous speed.
The synchronous motor with damper bars in its rotor pole shoes, runs as a squirrel cage
induction motor, from standstill up to near its synchronous speed.
18. 18
If the field winding is now energised from a DC source, the rotor and stator poles will
magnetically lock together provided the rotor poles just approaching the stator poles
are of opposite polarity.
Once the rotor starts rotating at synchronous speed, no emf would be induced in
damper bars.
22. 22
(ii) Synchronous Induction Motor: -
The rotor of synchronous induction motor is similar to the rotor of wound-rotor
induction motor. At the time of starting, high resistance is inserted in the rotor circuit in
order to develop high starting torque as in a wound rotor induction motor.
As the motor speeds up, the external resistance is gradually reduced to zero.
Zero external rotor resistance would cause the rotor to rotate at a speed very near to
synchronous speed. At this time, rotor short-circuit is removed and rotor winding is
switched over to DC supply.
The rotor poles thus created would be magnetically locked with the stator poles and the
motor would start running as a synchronism motor.