Interview Questions Answers in Electrical Engineering

Question { 16173 }

We have laid the single core Armoured cable 7 nos ( 2 each
phase & 1 neutral ) to cater our electrical load .
the issue is though we have Glanded the cable both the end
also givan the earthing to the panel both the end we are
facing a heavy sparking at the gland side. what could be
the reason.

Answer

Guys,

let me clear that the earthing is proper we get the value
0.1ohm. We have used double compress gland which is fixed
in proper way, there no such thing like looping, but still
the problem is there . please share what else can be the
cause ?

Is This Answer Correct ?

0 Yes

1 No

Question { 5427 }

is it possible to use a tranformer to regulate an unstable
system voltage?

Answer

Yes, you can maintain the desired voltage by using a
automatic voltage regulator .

Is This Answer Correct ?

3 Yes

2 No

Question { 8001 }

how to convert kw in to unit

Answer

KWH ( Unit ) = Kw * Hour

Is This Answer Correct ?

8 Yes

2 No

Question { TCS, 12620 }

what is frequancy

Answer

A magnitude of the voltage in one cycle.

Is This Answer Correct ?

2 Yes

5 No

Question { 12765 }

what is the formula to calculate kva genset required for a
given load in kw.

Answer

Kva Required is = KW/0.8( Power factor )
& as the DG set is prefered to run at 80% load of the total
capacity then the Rated capacity is KVA/0.8

If the load is 100 KW rhen KVa is 100/0.8 = 125 KVa & the
rated kva is 125/0.8 = 156.25 KVA say 160 kva D.G set is
required.

Is This Answer Correct ?

34 Yes

6 No

Question { 8000 }

Hello friends i am facing one problem in lighting panel.
Frequently neutral link near to MCCB is burning(firing. What
may be the reason for this one. Please answer me.

Answer

Mr. sunil.

The possible causes are.

1. Unbalance load
2. loose connection
3. Harmonics in the system

Is This Answer Correct ?

14 Yes

0 No

Question { 5795 }

how convert kvar to microfarade?
circuit diagram of infrared transmiter and receiver?

circuit diagram of Fm transmiter and receiver?

Answer

Kvar = vP x IC / 1000

Where IC = 2x 3.15 x f x c x v

where c is the capacitance.

Is This Answer Correct ?

3 Yes

1 No

Question { 6962 }

we have two 11/.433 kv. distribution Transformer rating as
1000 kva & 500 kva , i wants to run parallel both transformer.
both transformer impendence voltage is 5.24%, How can we run
both t/f, & how sharing the load

Answer

As mentioned if the capacity, the vectror group ,
Impedance is equall you can connect both the transformet
in parrel just make sure that the Phase sequence for both
the transformer is same at the time of parallel & as the %
impedance is same the laad sharing will be equall.

Is This Answer Correct ?

0 Yes

1 No

Question { 11954 }

in our transmisison sub station why we step down firstly
132kv\33kv then 33kv to 11kv. can we direct step down 132kv
to 11kv.

Answer

Dear Mottaleb

You can certenly step down the voltage from 132 KV to 11
kv , however in Distribution Substation diffrent level of
voltage comes across so as in your case your substation
should have a diffrent outgoin feeders of 33 kv so your
distribution is 132KV / 33 KV / 11 KV...

Is This Answer Correct ?

2 Yes

4 No

Question { 19262 }

what is the difference between delta-delta, delta-star
transformer???

Answer

Delta - de;ta transfomer is used at Gnerating station or a
receiving station for Change of Voltage , generally it is
used where the Voltage is high & Current is low.
where Delta star is a distribution kind of transfoemr where
from secondary star neutral is taken as a return path .
this configuration is used for Step down voltage phenomina

Is This Answer Correct ?

26 Yes

0 No

Question { Birla, 14053 }

why not use capacitor in Dg sets.

Answer

Because receative power generated by Capacity may harm the
AVR this is the only reason.

Is This Answer Correct ?

1 Yes

2 No

Question { 5475 }

wat s the electronic device used in the fan regulators
recently?

Answer

Most important part is triac

Is This Answer Correct ?

7 Yes

0 No

Question { 11373 }

what is the cable size we can use for 11kv and 33kv ?

Answer

size of the cable is based on current carring Capicity only
as on load. how ever 11KV & 33 KV can be considered for
insulation purpose only( phase to phase insulation ). for
that you can chose XLPE cable.

At first sight your question is completly out of phase....

Is This Answer Correct ?

14 Yes

4 No

Question { HCL, 19875 }

What is the working principle of VFD

Answer

In additon to what Pushpendra said VFD mean variable
frequency drive ( means a speed control my controlling
frequency ) as N= 120*F/P

If the frequency is decreased flux will increase hence
speed will decress . at the other hand if frequency will
increase flux will decrease & speed will increase...

Is This Answer Correct ?

31 Yes

6 No

Question { 6837 }

my 10 hp submersible pump is tripping when connected
through ELCB.I have checked the megger value of the coil's
with body.It was found to be 0.2mega ohm.that is leakage is
there.But when connected to mccb it is not tripping.no
leakage current in the motor.Is it safe to connect to mccb?
what are the problem's will arise if future?also tell me in
ELCB no neutral is connected to motor.than how ELCB was
working?

Answer

There may be a minor leakage in , also please check the
mAmp of the ElCB if it is 100ma then there is a possible
chance of tripping on minor leakage.. i suggest you to try
with 300ma ELCB even if get tips then you have to check the
motor winding & connecting cable thoroly.

Is This Answer Correct ?

9 Yes

1 No

virendra