Interview Questions Answers in Electrical Engineering

Question { 3099 }

Auto transformer starter gives the same effect as star/delta
strater if its turn ratio =
A 0.5 B 0.67
C o.66 D 0.577

Answer

D - 1/1.732

Is This Answer Correct ?

1 Yes

0 No

Question { 7342 }

A transformer has negative voltage regulation when its load
PF is
A zero B unity
C lagging D leading

Answer

D . Leading

Is This Answer Correct ?

22 Yes

0 No

Question { 9825 }

Why we use two wattmeter during block rotor test and no load test of
3phase induction motor? And how can we understand the neat power
requirement of from this test?

Answer

As the pf is very low, one of the 3 watt meters will show
negative reading

Is This Answer Correct ?

7 Yes

1 No

Question { 6496 }

What is the type of electrical earthing recommended in hard
rock area

Answer

6" dia deep( up to 75 m) bores ,40mm dia MS rod as
electrode and Bentonate clay for filling

Is This Answer Correct ?

1 Yes

2 No

Question { 4247 }

What will happen if we give the 3 phase supply to the rotor
of slipring induction motor?

Answer

Motor rotates but heavy is current is drawn resulting in
tripping of CB or fuse blow off .

Is This Answer Correct ?

0 Yes

0 No

Question { GTS, 3526 }

why some transformer without breather.

Answer

If it is also without conservator , it is vacuum sealed
transformer.Vacuum inside ,allows for expansion of oil

Is This Answer Correct ?

1 Yes

1 No

Question { 3327 }

what is the difference between H.T Or HV lines...?

Answer

HV and HT are one and the same

Is This Answer Correct ?

1 Yes

0 No

Question { 22659 }

The maximum demand of consumer is 2 kW and his daily energy
consumption is 20 units. Its Load Factor is
(1) 10.15% (2) 41.6 % (3) 50 % (4) 60%

Answer

Load factor = av load / peak load 20/24 kw is the av load .
Ans is (2)

Is This Answer Correct ?

20 Yes

17 No

Question { ABC, 4618 }

we have 3 phase 4 wire supply 230/415 V.AC and our
distribution is single phase or we have all single phase
220 v,ac operated appliances. and noted the current with
help of clamp meter Red to N = 20 Amps. Yellow to N = 45Amps
and Blue to N = 30 Amps ( total is 95 Amps ) what will be
neutral current on the main .

Answer

The currents measured are phase currents without reference
to neutral. The current in the neutral will be the vector sum

Is This Answer Correct ?

1 Yes

0 No

Question { Suzlon, 6636 }

KVA transformer of different frequencies of
50hz,100hz,500hz&1000hz. which one of these transformer has
big size? Give reason

Answer

In transformers back emf should be almost equal to the
applied voltage . For the same voltage ,less flux is
required at higher frequency. The core will be smaller ,and
hence the size

Is This Answer Correct ?

2 Yes

0 No

Question { 2619 }

Is there any relation between
transformer capacity and its
bdv?

Answer

No ,only the voltage.

Is This Answer Correct ?

0 Yes

0 No

Question { 7288 }

What is the difference between a Distribution Transformer
and a Power Transformer.

Answer

AS POWER TR SUPPLIES POWER TO DIST TRS

Is This Answer Correct ?

1 Yes

5 No

Question { 3989 }

12.5 KVAR capacitor 440V gas filled, Its used for windmill
purpose, How can i know about microfarad value for this
capacitor

Answer

Find the current and > Xc . Use the formula Xc= 1/Cw to get
the value of C

Is This Answer Correct ?

1 Yes

0 No

Question { 2687 }

I am getting above 60 V as open delta voltage against single
phase unit ICT at tertiary delta formed and ICT getting
trippped on NDR. ICT tested and found in order. PTs provided
on tertiary are tested and in order. what may be the reason?

Answer

The question is vague

Is This Answer Correct ?

0 Yes

0 No

Question { Motwane, 4963 }

11kv = LT 440v , how many amp.supose 440v side 5000 amp
curent drown

Answer

200 A

Is This Answer Correct ?

4 Yes

1 No

k.prakashchandra