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Do AC induction motors have back EMF?
asked
Mar 15, 2018
by
anonymous
Do AC induction motors have back EMF?
ac
induction
motors
back
emf
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asked
Mar 20, 2018
by
anonymous
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because?
Last answer:
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.
dc
shunt
motors
speed
back
emf
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1
answer
asked
Apr 27, 2020
by
anonymous
What is back emf?
What is back emf?
Last answer:
Back EMF: When a current carrying conductor is placed in a magnetic field it experiences a force; when it moves due to the force it (conductor) cuts the magnetic field due to which an emf is ... (hence the applied armature voltage) is opposed by the induced emf which is therefore called as Back emf.
what
is
back
emf
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asked
Mar 15, 2018
by
anonymous
What is back EMF of synchronous motor?
What is back EMF of synchronous motor?
back
emf
synchronous
motor
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answers
asked
Mar 15, 2018
by
anonymous
What is back EMF in inductor?
What is back EMF in inductor?
back
emf
inductor
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0
answers
asked
Mar 15, 2018
by
anonymous
What is the back EMF in Transformers?
What is the back EMF in Transformers?
back
emf
transformers
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answers
asked
Mar 15, 2018
by
anonymous
What is the back EMF of a dc motor?
What is the back EMF of a dc motor?
back
emf
dc
motor
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asked
Mar 15, 2018
by
anonymous
What is the back EMF of the motor?
What is the back EMF of the motor?
back
emf
motor
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asked
Mar 15, 2018
by
anonymous
What is the back EMF?
What is the back EMF?
Last answer:
When the armature of a d.c. motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence e.m.f. is induced in them as in a generator. The ... that energy conversion in a d.c. motor is only possible due to the production of back emf.
back
emf
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answer
asked
Mar 18, 2018
by
anonymous
The back emf of synchronous motor depends on?
The back emf of synchronous motor depends on?
Last answer:
The back emf of synchronous motor depends on load angle.
back
emf
synchronous
motor
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1
answer
asked
Mar 20, 2018
by
anonymous
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is?
Last answer:
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.
mechanical
power
shunt
motor
maximum
ratio
back
emf
voltage
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1
answer
asked
Mar 20, 2018
by
anonymous
What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
Last answer:
The armature may burn if the back e.m.f. of a D.C. motor vanishes suddenly.
back
emf
dc
motor
vanishes
suddenly
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1
answer
asked
Sep 3, 2019
by
anonymous
Why are DC motors used in trains and not AC motors ?
Why are DC motors used in trains and not AC motors ?
Last answer:
The reason is torque. torque is inversely proportional to speed..i.e when th knowe train comes to rest position to motion.. initial speed is zero..so it requires high starting torque for ... current will flow through field and armature coils then maximum torque is available at the intial condition.
dc
motors
trains
ac
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138
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1
answer
asked
Apr 29, 2018
by
anonymous
Which of the following motors can run on both AC and DC?
Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
Last answer:
Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
motors
ac
dc
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113
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1
answer
asked
Apr 28, 2018
by
anonymous
Slot harmonics are reduced in induction motors by using
Slot harmonics are reduced in induction motors by using (A) fractional-pitch windings (B) fractional-slot windings (C) integral-slot windings (D) distributed windings
Last answer:
Slot harmonics are reduced in induction motors by using fractional-slot windings
slot
harmonics
induction
motors
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61
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1
answer
asked
Apr 28, 2018
by
anonymous
Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as
Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as (A) One-third of their synchronous speed (B) One-fifth of their synchronous speed (C) One-seventh of their synchronous speed (D) One-ninth of their synchronous speed
Last answer:
Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as One-seventh of their synchronous speed
crawling
squirrel
cage
induction
motors
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1
answer
asked
Sep 9, 2017
by
anonymous
is induction motor ac or dc?
Last answer:
Induction motor is a AC motor it is also known as asynchronous motor .
induction
motor
dc
ac
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1
answer
asked
Mar 20, 2018
by
anonymous
The capacitors used in single-phase capacitor motors have no?
Last answer:
The capacitors used in single-phase capacitor motors have no polarity marking.
capacitors
used
single-phase
capacitor
motors
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105
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1
answer
asked
Mar 20, 2018
by
anonymous
Most of the fractional horsepower motors have either?
Last answer:
Most of the fractional horsepower motors have either plain or sleeve bearings.
fractional
horsepower
motors
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59
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1
answer
asked
Aug 17, 2019
by
anonymous
Self induced emf and Mutually induced emf
Self induced emf and Mutually induced emf
Last answer:
(i) Self-induced e.m.f.: The e.m.f. induced in a coil due to the change of its own flux linked with it, is called self-induced e.m.f. (ii) Mutually induced e.m.f.: The e.m.f. induced in a coil due to the changing current in the neighbouring coil, is called mutually induced e.m.f.
mutually
induced
emf
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1
answer
asked
Sep 7, 2018
by
anonymous
What is Phase sequence? Draw waveforms of 3 phase emf.
What is Phase sequence? Draw waveforms of 3 phase emf.
Last answer:
Phase sequence: It is the order in which the three phases reach their peak or maximum values. It is shown in below fig. the phase sequence is A-B-C (or R-Y-B). In the following waveforms, it is ... 120º, B- phase voltage attains its positive maximum value. So the phase sequence is R-Y-B.
phase
sequence
waveforms
emf
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1
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asked
Sep 4, 2018
by
anonymous
Compare statically induced emf with dynamically induced emf on any four points.
Compare statically induced emf with dynamically induced emf on any four points.
Last answer:
Statically induced emf Dynamically induced emf Emf is induced without any relative motion between conductor and magnetic field. Emf is induced due to relative motion between conductor ... induced in transformer windings e.g emf induced in Generator, Alternator armature windings
compare
statically
induced
emf
dynamically
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2
answers
asked
Aug 8, 2018
by
anonymous
Explain the term self induced EMF with a neat diagram.
Explain the term self induced EMF with a neat diagram.
self
induced
emf
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0
answers
asked
Aug 8, 2018
by
anonymous
Define: 1) statically induced EMF 2) dynamically induced EMF
Define: 1) statically induced EMF 2) dynamically induced EMF Write the names of equipments in which these two types of EMF get induced
Last answer:
Concept of statically induced emf: The emf induced in coil or conductors without any relative motion between it and magnetic field is called statically induced emf. When conductor is stationary and flux ... it. This emf is dynamically induced emf. e.g. Emf induced in generators, alternator.
statically
induced
emf
dynamically
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370
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3
answers
asked
Aug 8, 2018
by
anonymous
List the two types of induced EMF.
List the two types of induced EMF.
Last answer:
There are two types of EMF one is statically induced EMF and second is dynamically induced EMF.
induced
emf
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1
answer
asked
Mar 14, 2018
by
anonymous
Do cell phones use AC or DC current?
Do cell phones use AC or DC current?
Last answer:
DC of course.
cell
phones
use
ac
dc
current
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177
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2
answers
asked
Mar 11, 2018
by
anonymous
Why do we use AC current in our homes?
Why do we use AC current in our homes?
Last answer:
We used it for cooking rice, For washing clothes and for lights in the house.
use
ac
current
homes
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174
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3
answers
asked
Mar 15, 2018
by
anonymous
Why does induction motor have high starting current?
Why does induction motor have high starting current?
Last answer:
In induction motor , the flux produce is quadrature to the applied voltage. Since when we are going to start motor , there is no flux present inside . So in order to lets say compensate it ... times of current to further increase flux. So that is reason for high starting current in induction motor
induction
motor
high
starting
current
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115
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2
answers
asked
Apr 27, 2020
by
anonymous
Explain dynamic and static induced emf with neat diagram.
Explain dynamic and static induced emf with neat diagram.
Last answer:
Dynamically Induced EMF:- In this case, either coil moves or magnet moves, so that there is relative motion between coil & magnetic field. Thus magnetic field is cut by coil & emf is induced in it. The emf ... The expression for induced EMF is e= -L(di/dt) or = -N(dϕ/dt).
explain
dynamic
and
static
induced
emf
with
neat
diagram
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1
answer
asked
Dec 13, 2019
by
UMESH y
Emf definition
emf
definition
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117
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0
answers
asked
Apr 29, 2018
by
anonymous
The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors
The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is (1) 1000V (2) 100V (3) 600V (4) 10,000V
Last answer:
The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is 1000V
induced
emf
armature
lap-wound
four-pole
dc
machine
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161
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1
answer
asked
Apr 28, 2018
by
anonymous
The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is
The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is (A) 2/3 (B) 5/6 (C) 7/8 (D) 6/7
Last answer:
The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is 6/7
fractional-pitch
7th
harmonic
emf
wave
alternator
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289
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1
answer
asked
Dec 22, 2017
by
anonymous
What is the EMF equation of the transformer?
What is the EMF equation of the transformer?
Last answer:
E1 =2(3.142)fN1 (flux)1E2 =2(3.142)fN2(flux)2
emf
equation
transformer
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123
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1
answer
asked
Aug 17, 2019
by
anonymous
Suggest electric motors for i) traction ii) crane iii) lathe machine iv) domestic fan.
Suggest electric motors for i) traction ii) crane iii) lathe machine iv) domestic fan.
Last answer:
i) Traction :- DC Series motor ii) Crane :- DC Series motor iii) Lathe machine :- 3 phase Induction motor or DC shunt motor iv) Domestic fan :- 1 phase induction motor
electric
motors
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36
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1
answer
asked
Aug 17, 2019
by
anonymous
State which electric motors are generally used in electro agro systems with reason.
State which electric motors are generally used in electro agro systems with reason.
Last answer:
1) 3 phase induction motor is used in electro agro system for water pumping from wells as 3 phase ac supply is easily available, cost of induction motor is less, maintenance free being rugged ... as 1 phase ac supply is easily available for domestic purpose, repair is simple and easily available.
electric
motors
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66
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1
answer
asked
Aug 17, 2019
by
anonymous
State factors for selection of motors as drive.
State factors for selection of motors as drive.
Last answer:
Following Factors governing / or are considered while selecting electric drive (Motor) for particular application: Factors to be considered for selection of Electrical Drives: 1) Nature of Supply:- ... level, load equalization 7) Cost: - Capital, Running and maintenance cost should be less.
motors
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1.2k
views
2
answers
asked
Jul 30, 2019
by
anonymous
Compare variable reluctance and permanent magnet motors.
Compare variable reluctance and permanent magnet motors.
Last answer:
Variable reluctance Motor Permanent magnet motors The rotor is not magnetised The rotor is magnetised High torque to inertia ratio Low torque to inertia ratio ... rotor has salient pole construction The rotor has mostly smooth cylindrical type of construction.
variable
reluctance
permanent
magnet
motors
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2.4k
views
1
answer
asked
Jul 30, 2019
by
anonymous
What are the factors to be considered while selection of motors for different drives?
What are the factors to be considered while selection of motors for different drives?
Last answer:
Following Factors are considered while selecting electric drive (Motor) for particular application: Factors to be considered for selection of Electrical Drives: 1) Nature of Supply:- Whether supply ... , load equalization 7) Cost: - Capital, Running and maintenance cost should be less.
motors
different
drives
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66
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1
answer
asked
Jul 24, 2019
by
ZAHID
3 phase motor 42 hp same ratting two motors but pole change 2 and 4 pole tell me difference amp of both motors
3 phase motor 42 hp same ratting two motors but pole change 2 and 4 pole tell me difference amp of both motors
motors
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2.5k
views
0
answers
asked
Mar 11, 2018
by
anonymous
How do induction heaters work?
How do induction heaters work?
induction
heaters
work
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31
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0
answers
asked
Mar 18, 2018
by
anonymous
Which motor have more efficiency, synchronous motor or induction motor?
Which motor have more efficiency, synchronous motor or induction motor?
Last answer:
Synchronous motor has more efficiency.
efficiency
synchronous
induction
motor
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61
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1
answer
asked
May 8, 2018
by
anonymous
A relay used for protection of motors against overload is :
A relay used for protection of motors against overload is : (A) Impedance relay (B) Electromagnetic attraction type (C) Thermal relay (D) Buchholz's relay
Last answer:
A relay used for protection of motors against overload is : Thermal relay
relay
used
protection
motors
overload
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232
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1
answer
asked
Apr 29, 2018
by
anonymous
Damper winding is provided in 3 phase synchronous motors to :
Damper winding is provided in 3 phase synchronous motors to :
Last answer:
Damper winding is provided in 3 phase synchronous motors to : provide starting torque and prevent hunting
damper
winding
3-phase
synchronous
motors
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69
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1
answer
asked
Apr 29, 2018
by
anonymous
Stepper motors are used in
Stepper motors are used in (1) printers (2) lifts (3) amplifiers (4) oscillators
Last answer:
Stepper motors are used in printers
stepper
motors
used
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46
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1
answer
asked
Apr 28, 2018
by
anonymous
Which of the following test is usually conducted to determine the efficiency of traction motors ?
Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.
Last answer:
Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.
traction
motors
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205
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1
answer
asked
Apr 26, 2018
by
anonymous
Which of the following motors is being extensively used in servo applications ?
Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these
Last answer:
Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these
motors
servo
applications
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146
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1
answer
asked
Mar 20, 2018
by
anonymous
During rheostat braking of D.C. series motors?
Last answer:
During rheostat braking of D.C. series motors motor is run as a generator.
rheostat
braking
dc
series
motors
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62
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1
answer
asked
Mar 20, 2018
by
anonymous
D.C. shunt motors are used for driving?
Last answer:
D.C. shunt motors are used for driving machine tools.
dc
shunt
motors
used
driving
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68
views
1
answer
asked
Mar 20, 2018
by
anonymous
Why are the D.C. motors preferred for traction applications?
Last answer:
The D.C. motors preferred for traction applications beacuse the speed is inversely proportional to the torque and the torque is proportional to square of armature current.
dc
motors
traction
applications
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96
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1
answer
asked
Mar 20, 2018
by
anonymous
In case of conductively compensated D.C. series motors, the compensating winding is provided?
Last answer:
In case of conductively compensated D.C. series motors, the compensating winding is provided in series with armature winding.
dc
motors
series
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71
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1
answer
asked
Mar 20, 2018
by
anonymous
A direct online starter is used for starting motors?
Last answer:
A direct online starter is used for starting motors up to 5 H.P.
direct
online
starter
starting
motors
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1
answer
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