Interview Questions Answers in Electrical Engineering

Question { 11532 }

How many types Switchgears?

Answer

high , medium and low voltage switchgears as far as i know

Is This Answer Correct ?

14 Yes

5 No

Question { 5678 }

what is the working principle of induction motor

Answer

3 phase induction motor:

v giv 3phase supply to 3 phase stator winding, rotating
magnetic field running at synchronus speed is
produced.initially rotor is at standstill position (@ zero
rpm).this rotating magnetic field vil sweep over rotor.
thus there is cutting of flux lines. an emf is induced.
bcoz of this emf,a current is induced.now A CURRENT
CARRYING CONDUCTOR PLACED IN A MAGNETIC FIELD PRODUCES A
TORQUE.thus motor runs.

Is This Answer Correct ?

5 Yes

0 No

Question { 3803 }

what is busbar. how many types of starter.what appartus
will be used to improve voltage.what is the function of
starter.what is b.h.p.what material is used for earthing.

Answer

busbar- is the one which has non-variable voltage and
frequency throughout.

starter-
dol starter, star delta, auto transformer,rotor rheostat
starter(only for slip ring type)..

function of a starter- to start a machine, to limit the
starting current, to provide overload protection, also to
provide undervotage protection.

Is This Answer Correct ?

4 Yes

0 No

Question { 5312 }

why do you give the dc supply to field of alternator

Answer

The rotor of alternator consists of a coil of wire wrapped
around an iron core. Current through the wire coil -
called "field" current - produces a magnetic field around
the core. The strength of the field current determines the
strength of the magnetic field. The field current is D/C,
or direct current so that the current flows in one
direction only, and is supplied to the wire coil

Is This Answer Correct ?

2 Yes

1 No

Question { Bhel, 9999 }

Why HT voltages are expressed in 11KV,22KV,33KV and so on? (ie
in times of 11)

Answer

every1 say the reason is form factor 1.1....but the actual
reason is,according to the international stds, for every
100V, 10% of voltage is added for the compensation of
transmission loss.

Is This Answer Correct ?

10 Yes

4 No

Question { 5892 }

What is the difference
between Earth and
Neutral?

Answer

earth is to carry fault currents whereas neutral carries
leakage current(durin star connection).

Is This Answer Correct ?

27 Yes

5 No

Question { Siemens, 4098 }

transform oil how going to act like ainsulation purpose

Answer

transformer oil is a mineral based oil that should have an excellent dielectric breakdown stength which makes it to withstand the electical stresses.its bond or interfacial tension is so strong that it does not give way for conduction till a particular limit of high voltage.main properties of a transformer oil is dielectric breakdown strength,acid number,colour,presence of water and interfacial tension

Is This Answer Correct ?

9 Yes

0 No

Question { SSIL, 7409 }

what is difference of electrical and electronics

Answer

electrical is field of engineering that deals with high
voltage and high current .i.e, simply telling applications
of high power systems.whereas electronics deals vid mainly
low power applications

Is This Answer Correct ?

7 Yes

3 No

Question { Essar, 11195 }

in transfomer which type of oil is use!

Answer

a highly refined mineral oil

Is This Answer Correct ?

16 Yes

2 No

Question { 8789 }

why there is a humming noise in transformer

Answer

simply speakin its because of the magnetostriction effect.

hey guys, i found the following link to be more informative
n understandable. to ave more knowledge on tis topic,plz
check it out without fail...

http://www.federalpacific.com/literature/drytrans/10transfor
mernoise.pdf

Is This Answer Correct ?

6 Yes

1 No

Question { Pepsi, 7854 }

what kind of battery is used in laptops

Answer

lithium ion batteries

Is This Answer Correct ?

11 Yes

0 No

Question { 4120 }

In separately excited m/c,we excite the field by a dc
source,what not with ac source?

Answer

in order to have stationary poles (fixed N and S),we use dc
source.

Is This Answer Correct ?

4 Yes

3 No

Question { 8631 }

What is meant by a linear
circuit and what is a non-
linear circuit?

Answer

any circuit that obeys ohm's law are called as linear
circuit n those that doesn't obey are called non-linear
circuit.

Is This Answer Correct ?

7 Yes

4 No

Question { 7194 }

WHY THE TRANSFORMER VALUE MEASURES IN KVA INSTEAD OF KW.

Answer

any device that acts as a source vil be rated in kva,n
hence transformer,generator,ups etc are rated in kva. n its
not becoz of copper loss n iron loss stories as mentioned
in some books.coz when i answered like this, i was told
wrong.if any improved answer, plz notify me.

Is This Answer Correct ?

5 Yes

2 No

Question { 3575 }

what is the difference b/w conductor and semicoductor

Answer

conductors are the substance that has mobile electrons which
moves from one atom to another CONSTANTLY(juz imagine line
of people passing the ball constantly as they get the ball
to their hand)..but semiconductors are those substance in
which the electrons does'nt move readily unless it is
doped(here distance between the people is large,so people
become lazy to pass the ball...this is case for undoped ..)

Is This Answer Correct ?

1 Yes

1 No

meenakshi