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Hot questions in Electrical Machines
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21
GATE Electrical 2013 | Question: 9
A single-phase transformer has no-load loss of $64W$,as obtained from an open-circuit test.when a short-circuit test is performed on it with $90\%$ of the rated current flowing in its both $LV$ and $HV$ winding,the measured loss is $81W$.The transformer has maximum ... $80.0\: \%$ of the rated current. $88.8 \:\%$ of the rated current.
A single-phase transformer has no-load loss of $64W$,as obtained from an open-circuit test.when a short-circuit test is performed on it with $90\%$ of the rated current f...
piyag476
1.5k
points
piyag476
asked
Feb 11, 2017
Electrical Machines
gate2013-ee
efficiency
winding
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–
0
votes
0
answers
22
GATE Electrical 2014 Set 3 | Question: 39
The load shown in the figure absorbs $4$ $kW$ at a power factor of $0.89$ lagging. Assuming the transformer to be ideal, the value of the reactance $X$ to improve the input power factor to unity is ___________.
The load shown in the figure absorbs $4$ $kW$ at a power factor of $0.89$ lagging.Assuming the transformer to be ideal, the value of the reactance $X$ to improve the inpu...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-3
loss-less-transformer
transformation-ratio
numerical-answers
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–
0
votes
0
answers
23
GATE Electrical 2014 Set 3 | Question: 13
The no-load 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 ____________.
The no-load 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 c...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-3
excitation
armature-winding
tarque
numerical-answers
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–
0
votes
0
answers
24
GATE Electrical 2014 Set 2 | Question: 39
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 $10$
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 ...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-2
hysterisis-loss
eddy-current-loss
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0
votes
0
answers
25
GATE Electrical 2014 Set 1 | Question: 13
A star connected $400\:V, 50\:Hz, 4$ pole synchronous machine gave the following open circuit and short circuit test results: Open circuit test: $V_{oc} = 400\: V (\text{rms}, \text{line-to-line})$ 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 __________.
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{r...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-1
open-circuit-test
short-ciruit-test
numerical-answers
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–
0
votes
0
answers
26
GATE Electrical 2015 Set 2 | Question: 22
The figure shows the per-phase equivalent circuit of a two-pole three-phase induction motor operating at $50$ Hz. The “air-gap” voltage, $V_{g}$ across the magnetizing inductance, is $210$ V rms, and the slip, $s$, is $0.05$. The torque (in Nm) produced by the motor is _________.
The figure shows the per-phase equivalent circuit of a two-pole three-phase induction motor operating at $50$ Hz. The “air-gap” voltage, $V_{g}$ across the magnetizin...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2015-ee-2
slip-speed
motor
winding
numerical-answers
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–
0
votes
0
answers
27
GATE Electrical 2014 Set 3 | Question: 37
A non-salient pole synchronous generator having synchronous reactance of $0.8$ $pu$ is supplying $1$ $pu$ power to a unity power factor load at a terminal voltage of $1.1$ $pu$. Neglecting the armature resistance, the angle of the voltage behind the synchronous reactance with respect to the angle of the terminal voltage in degrees is ________.
A non-salient pole synchronous generator having synchronous reactance of $0.8$ $pu$ is supplying $1$ $pu$ power to a unity power factor load at a terminal voltage of $1.1...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-3
pitch-factor
distribution-factor
numerical-answers
+
–
0
votes
0
answers
28
GATE Electrical 2015 Set 1 | Question: 48
A separately excited $DC$ motor runs at $1000$ rpm on no load when its armature terminals are connected to a $200$ ... , the speed rises to $520$ rpm. Neglecting the rotational losses, the full load armature current (in Ampere) is ____________.
A separately excited $DC$ motor runs at $1000$ rpm on no load when its armature terminals are connected to a $200$V DC source and the rated voltage is applied to the fiel...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2015-ee-1
separately-excited
no-load-armature-current
numerical-answers
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–
0
votes
0
answers
29
GATE Electrical 2014 Set 3 | Question: 38
A separately excited $300$ $V$ $DC$ shunt motor under no load runs at $900$ $rpm$ drawing an armature current of $2$ $A$. The armature resistance is $0.5$ $Ω$ and leakage inductance is $0.01$ $H$. When loaded, the armature current is $15$ $A$. Then the speed in $rpm$ is _____
A separately excited $300$ $V$ $DC$ shunt motor under no load runs at $900$ $rpm$ drawing an armature current of $2$ $A$. The armature resistance is $0.5$ $Ω$ and leakag...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-3
series-connection
synchronous-speed
numerical-answers
+
–
0
votes
0
answers
30
GATE Electrical 2014 Set 1 | Question: 36
The core loss of a single phase, $230/115\:V, 50\:Hz$ power transformer is measured from $230\:V$ side by feeding the primary $(230\: V \: \text{side})$ from a variable voltage variable frequency source while keeping the secondary open circuited. The core loss is measured to ... and $542\:W$ $468\:W$ and $582\:W$ $498\:W$ and $552\:W$ $488\:W$ and $562\:W$
The core loss of a single phase, $230/115\:V, 50\:Hz$ power transformer is measured from $230\:V$ side by feeding the primary $(230\: V \: \text{side})$ from a variable v...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-1
core-losses
primary-winding
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–
0
votes
0
answers
31
GATE Electrical 2015 Set 2 | Question: 5
Match the following: ... $P-1; Q-3; R-1; S-2$ $P-1; Q-2; R-3; S-3$ $P-3; Q-1; R-2; S-1$
Match the following:$\begin{array}{|l|l|l|l|} \hline & \textbf{Instrument Type} & & \textbf{Used for} \\ \hline P. & \text{Permanent magnet moving coil} & 1. & \text{DC...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2015-ee-2
instrumentation
electric-machines
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–
0
votes
0
answers
32
GATE Electrical 2014 Set 1 | Question: 37
A $15\: kW, 230\: V\:dc$ shunt motor has armature circuit resistance of $0.4\: Ω$ and field circuit resistance of $230\: Ω.$ At no load and rated voltage, the motor runs at $1400$ ... , the motor draws a line current of $70\: A.$ Neglect armature reaction. The full load speed of the motor in rpm is _________.
A $15\: kW, 230\: V\:dc$ shunt motor has armature circuit resistance of $0.4\: Ω$ and field circuit resistance of $230\: Ω.$ At no load and rated voltage, the motor run...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-1
eletrical-machines
armature-winding
revolution-per-minute
numerical-answers
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–
0
votes
0
answers
33
GATE Electrical 2014 Set 2 | Question: 36
A $250$ $V$ $dc$ shunt machine has armature circuit resistance of $0.6$ $Ω$ and field circuit resistance of $125$ $Ω$. The machine is connected to $250$ $V$ supply mains. The motor is operated as a generator and then as a motor separately ... in both the cases is $50$ $A$. The ratio of the speed as a generator to the speed as a motor is ____________.
A $250$ $V$ $dc$ shunt machine has armature circuit resistance of $0.6$ $Ω$ and field circuit resistance of $125$ $Ω$. The machine is connected to $250$ $V$ supply main...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-2
core-resistance
armature-winding
numerical-answers
+
–
0
votes
0
answers
34
GATE Electrical 2015 Set 2 | Question: 23
A $4$-pole, separately excited, wave wound $DC$ machine with negligible armature resistance is rated for $230$ V and $5$ kW at a speed of $1200$ rpm. If the same armature coils are reconnected to form a lap winding, what is the rated voltage (in volts) and ... field circuit is left unchanged ? $230$ and $5$ $115$ and $5$ $115$ and $2.5$ $230$ and $2.5$
A $4$-pole, separately excited, wave wound $DC$ machine with negligible armature resistance is rated for $230$ V and $5$ kW at a speed of $1200$ rpm. If the same armature...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2015-ee-2
lap-winding
armature-core
revolution-per-minute
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–
0
votes
0
answers
35
GATE Electrical 2014 Set 2 | Question: 14
A single phase induction motor draws $12$ $MW$ power at $0.6$ lagging power. A capacitor is connected in parallel to the motor to improve the power factor of the combination of motor and capacitor to $0.8$ lagging. Assuming ... reactive power drawn by the motor remains same as before, the reactive power delivered by the capacitor in $MVAR$ is __________.
A single phase induction motor draws $12$ $MW$ power at $0.6$ lagging power. A capacitor is connected in parallel to the motor to improve the power factor of the combinat...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-2
induction
magnetic-flux
numerical-answers
+
–
0
votes
0
answers
36
GATE Electrical 2014 Set 2 | Question: 13
A three-phase, $4$-pole, self excited induction generator is feeding power to a load at a frequency $f_1$. If the load is partially removed, the frequency becomes $f_2$. If the speed of the generator is maintained at $1500$ $rpm$ ... $f_2> 50 Hz$ $f_1,f_2< 50Hz$ and $f_2> f_1$ $f_1>50 Hz$ and $f_2< 50 Hz$
A three-phase, $4$-pole, self excited induction generator is feeding power to a load at a frequency $f_1$. If the load is partially removed, the frequency becomes $f_2$. ...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Feb 11, 2017
Electrical Machines
gate2014-ee-2
revolution-per-minute
winding
+
–
0
votes
0
answers
37
GATE Electrical 2016 Set 1 | Question: 25
If an ideal transformer has an inductive load element at port $2$ as shown in the figure below, the equivalent inductance at port $1$ is $nL \\$ $n^{2}L \\$ $\dfrac{n}{L} \\$ $\dfrac{n^{2}}{L}$
If an ideal transformer has an inductive load element at port $2$ as shown in the figure below, the equivalent inductance at port $1$ is$nL \\$$n^{2}L \\$$\dfrac{n}{L} \\...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Jan 29, 2017
Electrical Machines
gate2016-ee-1
turn-ratio
inductive-load
coil
+
–
0
votes
0
answers
38
GATE Electrical 2016 Set 2 | Question: 3
The following figure shows the connection of an ideal transformer with primary to secondary turns ratio of $1:100$. The applied primary voltage is $100 V$ (rms), $50 Hz, AC$. The rms value of the current $I$, in ampere, is _________.
The following figure shows the connection of an ideal transformer with primary to secondary turns ratio of $1:100$. The applied primary voltage is $100 V$ (rms), $50 Hz, ...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Jan 29, 2017
Electrical Machines
gate2016-ee-2
isolation
windings
turn-ratio
numerical-answers
+
–
0
votes
0
answers
39
GATE Electrical 2016 Set 2 | Question: 17
A $50$ MVA, $10$ kV, $50$ Hz, star-connected, unloaded three-phase alternator has a synchronous reactance of $1$ p.u. and a sub-transient reactance of $0.2$ p.u. If a $3$-phase short circuit occurs close to the generator terminals, the ratio of initial and final values of the sinusoidal component of the short circuit current is ________.
A $50$ MVA, $10$ kV, $50$ Hz, star-connected, unloaded three-phase alternator has a synchronous reactance of $1$ p.u. and a sub-transient reactance of $0.2$ p.u. If a $3$...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Jan 29, 2017
Electrical Machines
gate2016-ee-2
reactive-power-supplier
field-emf
electrical-angle
mechanical-angle
numerical-answers
+
–
0
votes
0
answers
40
GATE Electrical 2016 Set 2 | Question: 22
The direction of rotation of a single-phase capacitor run induction motor is reversed by Interchanging the terminals of the AC supply. Interchanging the terminals of the capacitor. Interchanging the terminals of the auxiliary winding. Interchanging the terminals of both the windings.
The direction of rotation of a single-phase capacitor run induction motor is reversed byInterchanging the terminals of the AC supply.Interchanging the terminals of the ca...
makhdoom ghaya
9.4k
points
makhdoom ghaya
asked
Jan 29, 2017
Electrical Machines
gate2016-ee-2
pitch-factor
coil-span
stator-slots
flux-per-pole
+
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