Interview Questions Answers in Electrical Engineering

Question { 4770 }

if the stetor speed (N S) increase by 20% then the rotor speed will be increased by 20% is it true. ?

Answer

Stator rotating ?

Is This Answer Correct ?

0 Yes

0 No

Question { 3095 }

what is function of reactor coil in Power factor correction
panel

Answer

To compensate for leading pf

Is This Answer Correct ?

4 Yes

0 No

Question { 4195 }

what r the tests on the 3 phase transformers

can any one explain how to test using megger on transformers

thx

Answer

With all the connections removed 1.Primary to body 2. Sec to
body 3.Between Pr and Sec .Find PI value also

Is This Answer Correct ?

1 Yes

0 No

Question { 3260 }

How to calculate amount of copper used in a motor (AC&DC), generator and transformer? Datasheet provides power rating and mass of the equipment....can we somehow use this available info.

Answer

Total Number of turns,Av length of turn ,sectional area ,density

Is This Answer Correct ?

3 Yes

0 No

Question { 2878 }

what is the MF if CT ratio is 500/5 and in meter
specification is 3.75 REVS/KWH?

Thanks and Regards
Selvendran.N

Answer

M.F.has nothing to do with rev/KWH

Is This Answer Correct ?

4 Yes

0 No

Question { 3574 }

Why relay connected R
phase and B phase.?

Answer

OCRs are connected to R and B phases in series, generally
and they can be connected any two phases

Is This Answer Correct ?

2 Yes

0 No

Question { 2453 }

If ct ratio is 250/1 and mtr is of 5 amp, what will be mf?

Answer

If the rating of meter is 5 A max ,MF will be 250 only as the rating of meter has no bearing on MF . Not advisable to use for accuracy at low loads .

Is This Answer Correct ?

2 Yes

0 No

Question { 5412 }

i HP = ??
746 watts or 735.5
and how??

Answer

It is 746 w ,but rounded off to 750 w

Is This Answer Correct ?

1 Yes

12 No

Question { HB, 3408 }

Why not connect relay
Y phase for over
current and earth fault

Answer

You can provide OCR to Y phase . EFR is connected to any
phase . In case of 2 OCR + 1 EFR scheme ,EFR is not
connected to Y phase . You think so ,as OCR s are provided
to R and B phases

Is This Answer Correct ?

0 Yes

1 No

Question { 4521 }

why write 500v on line tester (Test pen)

Answer

You can safely test up to 500 V

Is This Answer Correct ?

1 Yes

0 No

Question { 2708 }

How much width of the land shall have to be left below the
EHT line of 440 kv as per the rule. i am told that a
corridor of 35 M width is to be left free below 220 kv line.
please confirm

Answer

52M for 400 KV line

Is This Answer Correct ?

0 Yes

0 No

Question { 4405 }

I have a generator of 300kw.400V,50hz . what is means
can i assume the load Red Phase with Neutral 300kw.Yellow phase with neutral 300kw and Blue with neutral also 300Kw. or - red with neutral 100kw same as yelloe and blue phase also giving 100kw with neutral respectively

Answer

It is the total load .i.e . 100 x 3

Is This Answer Correct ?

2 Yes

0 No

Question { 3462 }

Why we are testing cables with dc?

Answer

To build up a steady voltage (potential)between test points

Is This Answer Correct ?

4 Yes

0 No

Question { 2987 }

why using earth testing rod 15 meter 30 meter long to each
other?

Answer

1 : 2 ratio is to be maintained .You can go in for 30 and 60
and that will be more accurate

Is This Answer Correct ?

3 Yes

0 No

Question { Ambuja, 2872 }

L&T ACB C-POWER OF 800A FAULS TRIPING AT THE TIME OF 110KW
MOTOR STARTS WITH EARTH FAULT RELEASE

Answer

If it is new and under test ,CT might have been provided on
neutral instead of phase.If not , mostly due to pole
discrimination ( all poles not closing simultaneously ).
Disable instant element while closing .

Is This Answer Correct ?

0 Yes

0 No

k.prakashchandra