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Hot questions in Electrical Machines
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1
GATE2014238
A 20pole alternator is having $180$ identical stator slots with $6$ conductors in each slot. All the coils of a phase are in series. If the coils are connected to realize singlephase winding, the generated voltage is $V_1$. If the coils are reconnected to realize threephase starconnected ... layer winding, the ratio $V_1$/$V_2$ is $\frac{1}{\sqrt{3}}$ $\frac{1}{2}$ $\sqrt{3}$ $2$
asked
Feb 12, 2017
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Electrical Machines
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makhdoom ghaya
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9.3k
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gate2014ee2
fullpitchedwinding
generator
0
votes
0
answers
2
GATE2014311
In a synchronous machine, hunting is predominantly damped by mechanical losses in the rotor iron losses in the rotor copper losses in the stator copper losses in the rotor
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Feb 12, 2017
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Electrical Machines
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makhdoom ghaya
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gate2014ee3
damperwinding
corelosses
0
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0
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3
GATE2014327
The mean thickness and variance of silicon steel laminations are $0.2 mm$ and $0.02$ respectively. The varnish insulation is applied on both the sides of the laminations. The mean thickness of one side insulation and its variance are$0.1 mm$ and $0.01$ respectively. If the transformer core is made ... are $30 mm$ and $0.22$ $30 mm$ and $2.44$ $40$ mm and $2.44$ $40 mm$ and $0.24$
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Electrical Machines
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makhdoom ghaya
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gate2014ee3
insulation
core
0
votes
0
answers
4
GATE2014237
A threephase slipring induction motor, provided with a commutator winding, is shown in the figure. The motor rotates in clockwise direction when the rotor windings are closed. If the rotor winding is open circuited and the system is made to run at rotational speed fr with the help of primemover in anti ... $f$ $f_r$ and $f$ $f$  $f_r$ and $f$+$f_r$ $f$ + $f_r$ and $f$$f_r$
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Feb 12, 2017
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Electrical Machines
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makhdoom ghaya
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9.3k
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gate2014ee2
primemover
sliprings
commutator
0
votes
0
answers
5
GATE201343
The following arrangement consists of an ideal transformer and an attenuator which attenuates by a factor of $0.8$. An ac voltage $V_{WX1}=100V$ is applied across $WX$ to get an open circuit voltage $Y_{YZ1} $ across $YZ$. Next, an ac voltage$V_{YZ2}=100V$ ... respectively, $125/100$ and $80/100$ $100/100$ and $80/100$ $100/100$ and $100/100$ $80/100$ and $80/100$
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Feb 12, 2017
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piyag476
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gate2013ee
turnratio
primary
secondary
0
votes
0
answers
6
GATE2015149
A DC motor has the following specifications: $10$ hp, $37.5$ A, $230$ V; flux/pole = $0.01$ Wb, number of poles = $4$, number of conductors = $666$, number of parallel paths = $2$. Armature resistance = $0.267 \Omega$. The armature reaction is negligible ... W. The motor operates from a $230$ V DC supply. If the motor runs at $1000$ rpm, the output torque produced (in Nm) is ________.
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Feb 12, 2017
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Electrical Machines
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9.3k
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gate2015ee1
armatureresistance
outputtorque
numberofparallelpaths
numericalanswers
0
votes
0
answers
7
GATE2014312
A single phase induction motor is provided with capacitor and centrifugal switch in series with auxiliary winding. The switch is expected to operate at a speed of $0.7$ $Ns$, but due to malfunctioning the switch fails to operate. The torquespeed characteristic of the motor is represented by
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gate2014ee3
torquespeed
characteristic
auxiliarywinding
0
votes
0
answers
8
GATE2014239
For a single phase, two winding transformer, the supply frequency and voltage are both increased by $10%$. The percentage changes in the hysteresis loss and eddy current loss, respectively, are $10$ and $21$ $10$ and $21$ $21$ and $10$ $21$ and $10$
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Electrical Machines
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gate2014ee2
hysterisisloss
eddycurrentloss
0
votes
0
answers
9
GATE201320
The angle $\delta$ in the swing equation of a synchronous generator is the angle between stator voltage and current. angular displacement of the rotor with respect to the stator. angular displacement of the stator $\text{mmf}$ with respect to a synchronously rotating axis. angular displacement of an axis fixed to the rotor with respect to a synchronously rotating axis.
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Feb 12, 2017
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Electrical Machines
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piyag476
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1.5k
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gate2013ee
magnetomotiveforce
cagetyperotor
0
votes
0
answers
10
GATE2014113
A star connected $400\:V, 50\:Hz, 4$ pole synchronous machine gave the following open circuit and short circuit test results: Open circuit test: $V_{oc} = 400\: V (\text{rms}, \text{linetoline})$ at field current, $I_f = 2.3 A$ ... $I_f = 1.5 A$ The value of per phase synchronous impedance in $Ω$ at rated voltage is __________.
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Feb 12, 2017
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Electrical Machines
by
makhdoom ghaya
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9.3k
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gate2014ee1
opencircuittest
shortciruittest
numericalanswers
0
votes
0
answers
11
GATE2015134
A $3$phase $50$ Hz square wave ($6$step) VSI feeds a $3$phase, $4$ pole induction motor. The VSI line voltage has a dominant $5^{th}$ harmonic component. If the operating slip of the motor with respect to fundamental component voltage is $0.04$, the slip of the motor with respect to $5^{th}$ harmonic component of voltage is _________.
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Feb 12, 2017
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Electrical Machines
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makhdoom ghaya
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gate2015ee1
harmonic
slip
numericalanswers
0
votes
0
answers
12
GATE2014340
The parameters measured for a $220V$/$110V$, $50$ $Hz$, singlephase transformer are: Self inductance of primary winding = $45$ $mH$ Self inductance of secondary winding = $30$ $mH$ Mutual inductance between primary and secondary windings = $20$ $mH$ Using the above parameters, the ... , $20mH$ and $40mH$ $5mH$, $80mH$ and $40mH$ $25mH$, $10mH$ and $20mH$ $45mH$, $30mH$ and $20mH$
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Feb 12, 2017
in
Electrical Machines
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makhdoom ghaya
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9.3k
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gate2014ee3
stepdowntransformer
corelosses
0
votes
0
answers
13
GATE2014111
An $8$ – pole, $3$ – phase, $50\: Hz$ induction motor is operating at a speed of $700\:\text{rpm}.$ The frequency of the rotor current of the motor in $Hz$ is _________.
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Feb 12, 2017
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Electrical Machines
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9.3k
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gate2014ee1
motorwinding
rotorcurrent
revolutionperminute
numericalanswers
0
votes
0
answers
14
GATE2014112
For a specified input voltage and frequency, if the equivalent radius of the core of a transformer is reduced by half, the factor by which the number of turns in the primary should change to maintain the same no load current is $1/4$ $1/2$ $2$ $4$
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Electrical Machines
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makhdoom ghaya
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gate2014ee1
transformationratio
corelosses
0
votes
0
answers
15
GATE2014138
A $3$ phase, $50$ $Hz$, six pole induction motor has a rotor resistance of $0.1\: Ω$ and reactance of $0.92\: Ω$. Neglect the voltage drop in stator and assume that the rotor resistance is constant. Given that the full load slip is $3\%$, the ratio of maximum torque to full load torque is $1.567$ $1.712$ $1.948$ $2.134$
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Feb 12, 2017
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Electrical Machines
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makhdoom ghaya
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gate2014ee1
inductionmotor
windingresistance
0
votes
0
answers
16
GATE2014325
The torquespeed characteristics of motor $(TM)$ and load $(TL)$ for two cases are shown in the figures $(a)$ and $(b)$. The load torque is equal to motor torque at points $P$, $Q$, $R$ and $S$ The stable operating points are $P$ and $R$ $P$ and $S$ $Q$ and $R$ $Q$ and $S$
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Electrical Machines
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gate2014ee3
tarque
speed
0
votes
0
answers
17
GATE2014336
An open circuit test is performed on $50$ $Hz$ transformer, using variable frequency source and keeping $V/f$ ratio constant, to separate its eddy current and hysteresis losses. The variation of core loss/frequency as function of frequency is shown in the figure The hysteresis and eddy current losses of the ... $62.5$ $W$ $312.5$ $W$ and $62.5$ $W$ $312.5$ $W$ and $250$ $W$
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Feb 12, 2017
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Electrical Machines
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gate2014ee3
corelosses
opencircuittest
0
votes
0
answers
18
GATE2014225
In a constant $V/f$ control of induction motor, the ratio $V/f$ is maintained constant from $0$ to base frequency, where $V$ is the voltage applied to the motor at fundamental frequency $f$. Which of the following statements relating to low ... from its rated value. At low frequency, the motor saturates. At low frequency, the stator flux remains unchanged at its rated value.
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Electrical Machines
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makhdoom ghaya
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9.3k
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gate2014ee2
frequencydrives
frequencyharmonics
0
votes
0
answers
19
GATE201321
Leakage flux in an induction motor is flux that leaks through the machine flux that links both stator and rotor windings flux that links none of the windings flux that links the stator winding or the rotor winding but not both
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gate2013ee
magneticflux
statorwinding
0
votes
0
answers
20
GATE2014313
The noload speed of a $230$ $V$ separately excited $dc$ motor is $1400$ $rpm$. The armature resistance drop and the brush drop are neglected. The field current is kept constant at rated value. The torque of the motor in $Nm$ for an armature current of $8$ $A$ is ____________.
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gate2014ee3
excitation
armaturewinding
tarque
numericalanswers
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