Interview Questions Answers in Electrical Engineering

What is the major difference between P.T. & C.V.T ? Why CVT
is used in HT Transmission line in place of P.T.?

Answer

PT we are using at low voltgae and CVT we are using at EHV
line , CVT has more accuracy than PT
capacitor divider drop the voltage

Is This Answer Correct ?

12 Yes

31 No

Question { 7989 }

How can be decreased the size of transformer?

Answer

what we require , if we want to increase the flux density

the core we are using is CRGO

and what about the voltage

Is This Answer Correct ?

1 Yes

0 No

Question { L&T, 18865 }

What is Electrical Engineering?

Answer

electriacal engineering is ffield of electricity
generation , taransmission , distribution , and give the
electricity to our commercial , industrial , domestic
consumers with protection

Is This Answer Correct ?

1 Yes

0 No

Question { 5225 }

what is grounding & what is the value of groumding rod 2.5m?

Answer

grounding is very neccesary

in 1960-80 we are not prefering ground , then what happen???
see in 3phase system , ur phase to phase touch and current
will increase ,and it takes more cuurent and damage the
insulation of equipment

but when ur using grounding , then u r using grounding ,
the current will flow through the ground and not affect the
insulation of equipment

i want to describe with that drawing but there is no place

Is This Answer Correct ?

2 Yes

0 No

Question { DRJ ARDE, 4751 }

can I connect step down transformer(25KvA,240V Phase to
phase)to output of online UPS(15KvA,440V PHASE TO PHASE)
Load connect to TRANSFORMER is 13KvA,240V PHASE TO PHASE.
please brief if it is wrong

Answer

no u r not connect the 440v ups , rating is not matched, ur
rating should be matched

Is This Answer Correct ?

2 Yes

2 No

Question { 11467 }

Why we use Y-Y connection in power transformer (8-10 MVA,
132 kV to 11 KV)and D-y in distribution transformer (2 MVA,
11 KV to 440 Volts)?

Answer

ok u r using any transformer , anywhere but
the important is what is ur need ?
if u want , in distribution u need 440v -phase to neutral
u r using star connection

u need 11kv hv , u use delta connection

the important is u r using neutral or not generally line
side transformer has delta connected

Is This Answer Correct ?

6 Yes

5 No

Question { 14106 }

A 11000/415V distribution transformer is fed 415V upon it's LT
side,Do I get 11000V upon it's Primary side ?

Answer

yes u get

Is This Answer Correct ?

3 Yes

0 No

Question { 49276 }

Why transformer neutral earthing? What is advantages?

Answer

neutral is grounded in transformer

1) is for REF (resricted earth fault protection)
2) to eliminate the archinng ground fault

Is This Answer Correct ?

10 Yes

2 No

Question { Bhel, 105359 }

what is tertiary winding in transformer?What is its purpose?

Answer

tertiary winding , when we require low voltage in
switchyard , we use 3 -winding auto transformer
220/132/11 kV
100/125/200 mva

Is This Answer Correct ?

13 Yes

17 No

Question { Alstom, 23769 }

I HAVE A 1 MVA TRANSFORMER, I WANT TO KNOW THE FAULT LEVEL OF
THE SYSTEM ( WHAT IS FAULT LEVEL PLEASE EXPLAIN WITH EXAMPLE)

Answer

the above answer is right

Is This Answer Correct ?

10 Yes

3 No

Question { L&T, 81786 }

what is the main purpose of line PT and bus PT?

Answer

pt is use for metering and protection purpose
line PT is a government line
and bus pt is customer pt
we have to synchronise that both
generally pt protect the line with undervoltage ,
overvolateg protection

Is This Answer Correct ?

5 Yes

30 No

Question { 12604 }

what is meant by phase &line voltage, how its differ from
each other ?

Answer

VL = 1.73* Vph

Is This Answer Correct ?

5 Yes

1 No

Question { Siemens, 24161 }

How you calculating the current for a 2.5 Sqmm cable.
A 30 Hp 3 phase AC motor of power what size of cable is
used for this motor.

Answer

we are measure through SWG ( standard wire guage
it measure the crossection of wire
2.5sqmm

Is This Answer Correct ?

13 Yes

20 No

Question { 5812 }

HOW DEFINE THE IP FOR ELECTRICAL EQUIPMENT AND WHAT IS THE
IP OF PANELS USING IN HAZARDOUS AREA ?

Answer

ip meaans ingress protection which we are standardf panels
IP 54 is using for panel , IP 54 means it protects through
moisture ,dust and water(not oil)

we are using heater in panel to dry the contacts of
switches and relays

Is This Answer Correct ?

6 Yes

0 No

Question { 18290 }

how can we find CT coil not working ?

Answer

check the DGA of OIL
check the PPM value
check the other gas value
check the IR value

Is This Answer Correct ?

2 Yes

8 No

malav