Interview Questions Answers in Electrical Engineering, Power Plant Engineering

Question { 7060 }

Simple calculation of improving power factor?

Answer

KVA^2 =KW^2 + KVAr^2. Reduce KVAr to improve pf

Is This Answer Correct ?

3 Yes

0 No

Question { 6540 }

A circuit breaker is a

Answer

Switch gear

Is This Answer Correct ?

0 Yes

0 No

Question { Power Plant, 32018 }

What is the use of NULL meter on AVR panel

Answer

To indicate that auto-tracking is on . i.e. manual channel excitation is equal to that of auto channel, in case auto fails .

Is This Answer Correct ?

11 Yes

0 No

Question { 6571 }

If we have 15000kw connected load in a factory than how much
power demand sanction should be taken from electricity board.
Pls provide complete calculation.

Answer

Only the connected is mentioned and not the peak load.
Maximum demand is registered only if that apparent load
lingers for more than 15 to 30 minutes (as set).You have to
consider load factor(?) also .Apply for 12000 KVA MD
initially and you can apply for higher ,later.Once you get
the MD sanctioned, you can not get it reduced during the
agreement period.

Is This Answer Correct ?

1 Yes

0 No

Question { 5813 }

Why 30°phase shift occur in star-delta transformer between
primary and secondary?

Answer

There has to be a shift ,just overlap vector diagrams and see

Is This Answer Correct ?

2 Yes

5 No

Question { 2240 }

can anibody tel me on what basis the transformer vector
groups are determined????

Answer

Coil end connections

Is This Answer Correct ?

0 Yes

0 No

Question { HNG, 5160 }

what is creep of energy meter?

Answer

Creep is slow continuous rotation of the disc at no load, with potential coil energized.

Is This Answer Correct ?

5 Yes

0 No

Question { Bhel, 5374 }

Excat meaning of
burden in only one word?

Answer

The load on it in VA

Is This Answer Correct ?

0 Yes

2 No

Question { 2820 }

why the manufacturer provide M and C terminals ? why they will
not internally short them ?

Answer

For using PT for potential coil

Is This Answer Correct ?

0 Yes

0 No

Question { 9442 }

What is the difference between Contactor and Circuit
breaker ?

Answer

Opening and closing are done manually in case of contactors
and for cb it is electrical

Is This Answer Correct ?

0 Yes

3 No

Question { 9442 }

What is the difference between Contactor and Circuit
breaker ?

Answer

My above answer appears to be wrong.Contactors are for
closing circuit and are to be opened manually.Circuit
breaker has a tripping (opening) mechanism and may have
closing mechanism also.

Is This Answer Correct ?

0 Yes

1 No

Question { 9442 }

What is the difference between Contactor and Circuit
breaker ?

Answer

You can add that contactors are to be operated off-load only

Is This Answer Correct ?

0 Yes

1 No

Question { 2582 }

For these 2 devices what their power ratings are ?

1) single phase : AC 220V & starting amps 3Amps (i.e.
starting torque) and the stabilized amps 2A ... For deep
freezer
2) single phase : AC 220V & starting amps 2.7Amps (i.e.
including the starting torque of a CRT monitor) and the
stabilized amps 1 Amps

thanks

Answer

Ignore the starting current as it is momentary

Is This Answer Correct ?

0 Yes

0 No

Question { 3782 }

We have .ht motor which is 60Hz.we run on 50Hz.so that it's speed reduce
but we had one prob.that motor winding temp increase up to 135 deg.we
want reduce this temp.what to do?we arrange ext.cooling fan but not much
effect.we want reduce this temp. Inhouse without affecting much.cost. also
don't want reWINDING OF MOTOR?

Answer

As you have reduced the speed ,the cooling effect of the
shaft mounted cooling fan is also reduced .Either you have
to reduce the load by about 10% or replace cooling fan .

Is This Answer Correct ?

0 Yes

0 No

Question { 3782 }

Answer

You may have to reduce the load more till you get the
desired temp rise

Is This Answer Correct ?

1 Yes

0 No

k.prakashchandra