Interview Questions Answers in Electrical Engineering

Question { 3739 }

If two hack saw blades, seperated by 1mm thick paper,are
connected across 230volts, and immersed in water,then they
start getting heat. This is fact,i dont know how they get
heated.Blades are not directly connected together.
Please if anybody knows the fact ,revert back to me

Answer

The water in between acts as a resistance /heater coil

Is This Answer Correct ?

0 Yes

0 No

Question { TATA, 6803 }

In a star-star connected h.t transformer why we use NGR on
the secondary (l.t)side.

Answer

NGR connected on primary does not limit the earth fault
current .

Is This Answer Correct ?

0 Yes

0 No

Question { 2058 }

in 220 kv substation,what is the mean of avr voltage reading?
means at oltc temp. 36 the avr voltage was 109v.so what the
mean of 109v

Answer

PT voltage

Is This Answer Correct ?

0 Yes

0 No

Question { HCL, 3853 }

electricity board have asked me what size meter i need fitted
in my garage, its a 415volt supply and i want to run six 20amp
supplies tolifts and things plus ten florry lights , what kva
meter do i need??

Answer

The total current will be 120A and you have to employ CT's
whose secondary current will decide the rating of meter. The
ETVM measures kva also .

Is This Answer Correct ?

1 Yes

1 No

Question { 3765 }

why can tv operate at low voltage??

Answer

Because of SMPS ( switch mode power supply )

Is This Answer Correct ?

0 Yes

0 No

Question { 4837 }

what do you mean by star point.its importance in ct & pt

Answer

Neutral point as in 3 phase transformer

Is This Answer Correct ?

0 Yes

0 No

Question { 2699 }

Three phase star connected PT transformer primary side one
phase fuse is blown what will be the output in secondary
side(Secondary side also three phase star connected)

Answer

One phase missing in secondary also

Is This Answer Correct ?

0 Yes

0 No

Question { 3914 }

What is proximeter? where it is used and why?

Answer

I think they are used in digital cameras for zooming

Is This Answer Correct ?

0 Yes

0 No

Question { Bhel, 6700 }

Can we use 11kv Trivector Metre or Energy metre instead
33kv Metre at 33kv Over Head Line metering purpose?

Answer

The voltage input to both the meters is 110 V.So, you can
use and pre-set meter constant is to be considered

Is This Answer Correct ?

2 Yes

1 No

Question { 4020 }

Why Nutral CT rating for Earth Fault Protection of Transformer neutral shall be 20% of Full load Current of Transformer

Answer

CT rating is the same as that of line CTs .Only the relay
setting for earth fault is 20 % of OCR

Is This Answer Correct ?

1 Yes

0 No

Question { Bhel, 4760 }

What is a soft start?

Answer

It is an electronic stater using thyristors for limiting
voltage by varying the firing angle

Is This Answer Correct ?

2 Yes

0 No

Question { 2028 }

can we use optical fibre to electrical power transmission ?

Answer

Yes ,for communication

Is This Answer Correct ?

1 Yes

0 No

Question { 4141 }

what is the difference between arc and spark

Answer

Arc is like a 'line' and spark a 'dot '

Is This Answer Correct ?

2 Yes

0 No

Question { 4267 }

Can we use generator transformer as step down transformer?
How?

Answer

Yes. If the aux tr is connected to GT and there is no generation ,the GT is back charged with grid duly isolating gen, for aux supply .

Is This Answer Correct ?

0 Yes

0 No

Question { Maruti Suzuki, 5919 }

why DOL starter is use in induction motor as it is not reduce
the starting torque

Answer

DOL starter is used for small motors having thin winding
wire of considerable resistance .Hence starting current will
not be very high.

Is This Answer Correct ?

5 Yes

0 No

k.prakashchandra