Hot questions in Electrical Machines / GO Electrical

0 votes

0 answers

1

A transformer is rated at 100kVA. At full load, its copper loss is 1200W, and its iron loss is 960W.

jeetmoni

120 points

jeetmoni asked Oct 28, 2022

0 votes

0 answers

2

GATE Electrical 2014 Set 2 | Question: 38
A $20$-pole 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 single-phase winding, the generated voltage is $V_1$. If the coils are reconnected to realize three-phase ... $V_1/V_2$ is $\dfrac{1}{\sqrt{3}} \\$ $\dfrac{1}{2} \\$ $\sqrt{3} \\$ $2$

A $20$-pole 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 real...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

3

GATE Electrical 2014 Set 3 | Question: 27
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 ... $0.22$ $30 \: mm$ and $2.44$ $40 \: mm$ and $2.44$ $40\: mm$ and $0.24$

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....

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

4

GATE Electrical 2014 Set 2 | Question: 37
A three-phase slip-ring 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 ... $f$ $f-f_r$ and $f$ $f-f_r$ and $f+f_r$ $f+f_r$ and $f-f_r$

A three-phase slip-ring induction motor, provided with a commutator winding, is shown in the figure. The motor rotates in clockwise direction when the rotor windings are ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

5

GATE Electrical 2014 Set 3 | Question: 25
The torque-speed 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 $S$

The torque-speed 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 point...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

6

GATE Electrical 2014 Set 3 | Question: 11
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

In a synchronous machine, hunting is predominantly damped bymechanical losses in the rotoriron losses in the rotorcopper losses in the statorcopper losses in the rotor

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

7

GATE Electrical 2013 | Question: 43
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$V_{YZ2}=100V$ is applied ... , $125/100$ and $80/100$ $100/100$ and $80/100$ $100/100$ and $100/100$ $80/100$ and $80/100$

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 $WX$ t...

piyag476

1.6k points

piyag476 asked Feb 11, 2017

0 votes

0 answers

8

GATE Electrical 2015 Set 1 | Question: 49
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 ... The motor operates from a $230$ V DC supply. If the motor runs at $1000$ rpm, the output torque produced (in Nm) is ________.

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 pa...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

9

GATE Electrical 2014 Set 3 | Question: 40
The parameters measured for a $220V/110V$, $50 \: Hz$, single-phase 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, ... $10 \: mH$ and $20 \: mH$ $45 \: mH$, $30 \: mH$ and $20 \: mH$

The parameters measured for a $220V/110V$, $50 \: Hz$, single-phase transformer are:Self inductance of primary winding $= 45 \: mH$Self inductance of secondary winding $=...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

10

GATE Electrical 2014 Set 1 | Question: 12
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 $1/4$ $1/2$ $2$ $4$

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 prim...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

11

GATE Electrical 2014 Set 2 | Question: 25
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 ... its rated value. At low frequency, the motor saturates. At low frequency, the stator flux remains unchanged at its rated value.

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 fundam...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

12

GATE Electrical 2015 Set 2 | Question: 21
A shunt-connected $DC$ motor operates at its rated terminal voltage. Its no-load speed is $200$ radian/second. At its rated torque of $500$ Nm, its speed is $180$ radian/second. The motor is used to directly drive a load whose ... . Neglecting rotational losses, the steady-state speed (in radian/second) of the motor, when it drives this load, is _________.

A shunt-connected $DC$ motor operates at its rated terminal voltage. Its no-load speed is $200$ radian/second. At its rated torque of $500$ Nm, its speed is $180$ radian/...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

13

GATE Electrical 2013 | Question: 20
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 ... a synchronously rotating axis. angular displacement of an axis fixed to the rotor with respect to a synchronously rotating axis.

The angle $\delta$ in the swing equation of a synchronous generator is theangle between stator voltage and current.angular displacement of the rotor with respect to the s...

piyag476

1.6k points

piyag476 asked Feb 11, 2017

0 votes

0 answers

14

GATE Electrical 2014 Set 1 | Question: 38
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 $1.567$ $1.712$ $1.948$ $2.134$

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...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

15

GATE Electrical 2014 Set 3 | Question: 12
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 torque-speed characteristic of the motor is represented by

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 \:...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

16

GATE Electrical 2014 Set 3 | Question: 36
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 ... $62.5$ $W$ $312.5$ $W$ and $62.5$ $W$ $312.5$ $W$ and $250$ $W$

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 ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

17

GATE Electrical 2015 Set 1 | Question: 34
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 _________.

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 operat...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

18

GATE Electrical 2013 | Question: 21
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

Leakage flux in an induction motor isflux that leaks through the machineflux that links both stator and rotor windingsflux that links none of the windingsflux that links ...

piyag476

1.6k points

piyag476 asked Feb 11, 2017

0 votes

0 answers

19

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

0 votes

0 answers

20

GATE Electrical 2015 Set 1 | Question: 21
A separately excited $DC$ generator has an armature resistance of $0.1 \Omega$ and negligible armature inductance. At rated field current and rated rotor speed, its open-circuit voltage is $200 V$. When this generator is operated at half the rated speed, with ... capacitor is connected will the voltage across it reach $25 V$? $62.25$ $69.3$ $73.25$ $77.3$

A separately excited $DC$ generator has an armature resistance of $0.1 \Omega$ and negligible armature inductance. At rated field current and rated rotor speed, its open-...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017