Interview Questions Answers in Electrical Engineering

Questions / { psilamparasan }

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Answers / { psilamparasan }

how does electrical train works and what type of motors are
used to drive the train?
which level of supply voltage is used?

Answer

First the train receive 25KV supply from the overhead
transmission line and it step down and converts it into D.C
voltage. And given to D.C series motor. Because the motor
needs heave starting torque to move the stationary train.

Anybody kindly give e a feedback.

Is This Answer Correct ?

166 Yes

19 No

Question { 8894 }

wha tis the ac motor used for traction system

Answer

SlipRing induction motor, because we can get high starting
torque by adding resistor to it's rotor.
We can change the torque as per our requirement.

Is This Answer Correct ?

4 Yes

3 No

Question { Jindal, 29820 }

Why HT cable have only 3 core ?

Answer

Basically the HT cable is used for transmission line only
not in distribution line. Because we are using delta
connection (Three phase Three wire system) for transmission
and star connection (Three phase Four four wire system). So
that's why the HT cables have three cores only.

Is This Answer Correct ?

58 Yes

5 No

Question { L&T, 19010 }

if we use fuse in neutral what will happen?

Answer

Fuse is used to limit overcurrent. So we have to use fuse
in phase only.

Neutal is for pass, if any faulty current or unbalanced
current. We dont know how much Ampere current flows through
the neutral during any fault or unbalance, it may be high
current also. If we use fuse in neutral during faulty
current the fuse in neutral will blown and it will camage
the unbalanced power system. And it will damage yje
components.

Is This Answer Correct ?

33 Yes

3 No

Question { 10664 }

Motor and transformer working with same principle so why
motor rotates while transformer not?

Answer

Because it is a stationary device so it will not ratate.
That's why the transformer is a most efficiency electrical
machine compare with motors.

Is This Answer Correct ?

3 Yes

5 No

Question { 24348 }

how to diffrentiate between ac & dc motors from a distance

Answer

We can identify the motor its A.C or D.C by their physical
appearance. Basically the A.C motors are shaply in round
because it has only stator winding as 4pole or 6pole. But
the motors are shaply in rectangle because it has poles as
well as interpoles to compensate the flux leakages. So we
can find out a motor it is A.C or D.C by their physical
appearance.
Anybody kindly give me a feedback about my
answere.

Is This Answer Correct ?

9 Yes

21 No

Question { 7715 }

1.wat is the purpose (or)function of regulator?

2.wat is the purpose of stabiliser?

Answer

Function Of Regulator: Regulator is a device is used to
control the speed by variying the input voltage.

Function Of Stabilisher: Stabilisher is a device used to
stabilise the supply voltage from low voltage or voltage
high voltage to a electronic system like T.V, Fridge, etc.
But in stabilisher we can not vary the voltage.

Is This Answer Correct ?

13 Yes

1 No

Question { Pricol, 20916 }

what is meant by power factor ?

Answer

POwer Factor is a cos angle between Voltage and current.

Is This Answer Correct ?

51 Yes

6 No

Question { NTPC, 56656 }

why the motor running in delta connection ? it can be in star?

Answer

Because the voltage in star connection is Vph=VL/square
root of three.
But in delta connection Vph=VL.
So in star connection is only for starting a motor.
But to run a motor through a delta winding. Becaus then
only full voltage given to motor and it will run in full
speed.

Is This Answer Correct ?

55 Yes

26 No

Question { BSL, 50028 }

what is the difference between concentrated winding and
Distributed winding in motor?

Answer

For Example:

Concentrated winding-Transformer

Distribution winding-Induction motor

Is This Answer Correct ?

39 Yes

58 No