Interview Questions Answers in Electrical Engineering, Electronics Communications, Mechanical Engineering, Automobile Engineering

what is reactive power?

Answer

satisfied with RAMA KRISHNA, the power which is returned to the supply is called the reactive power
actual power consumed is active power while total of both these is apparent power

Is This Answer Correct ?

0 Yes

0 No

Question { Polycab, 36397 }

Why do we give DC excitation to AC Synchronous motor??

Answer

because only dc current can produce the fixed pole i.e. the
poles produced by the dc current does not change with time
as in the case of the poles produced by ac current.
now when the stator of the machine is supplied the ac
current the rotating magnetic current is produced.
the dc excitation is necessary so that the poles produced
by the dc current and ac current both attrect each other
which will be responsible for the production of the torque.

Is This Answer Correct ?

46 Yes

6 No

Question { 6763 }

to improve the existing power factor whether capacitors
have to be added in series or parallel.and why

Answer

as we all know that the capacitor takes the leading current
thus the total current taken by the device also have a
leading current....as generally our load is inductive in
nature, which takes the lagging current, thus the
capacitive current also compensate the lagging current
causing the powert factor to improve

Is This Answer Correct ?

3 Yes

0 No

Question { 10339 }

1.Defination of Graund earth and neutral
2.

Answer

ground and earth are same things
these have zero potential.
under normal conditions(when the device is not in use) the
neutral can also be treated as at zero potential,but when
it is working then it has some potential with respect to
the EARTH

while in 3 phase star system ,the neutral got some voltage
if there exists an unbalance condition.......
for delta connection the earth is used as a neutral

Is This Answer Correct ?

0 Yes

0 No

Question { 10659 }

in trains i have seen the terminal which is connected at
the top of the train is positive .where is negative ?
track? i dont think so

Answer

it is right that the track itself acts as the return path for the current.
now what happen when u touch the railway track is "let me remind u that current always follows the path having minimum resistance" and the resistance of ur body will always b > the track

so u did't feel the shock.
ok

Is This Answer Correct ?

2 Yes

0 No

Question { 13826 }

WHY SECONDARY OF CT SHOULD NEVER BE KEPT OPEN CIRCUITED?

Answer

it ceases the back emf produced by the secondary of ct
this led to heavy inrush of current through primary as
there is no opposing emf
this may harm the person performing the experiment

Is This Answer Correct ?

3 Yes

10 No

Question { Reliance, 11162 }

Can we get the shock if Power system is unearth means delta
type take an rated voltage as 6.6 KV?

Answer

yes in this case
as the voltage is very high
the current flows through our body to earth

Is This Answer Correct ?

4 Yes

0 No

Question { 7017 }

what is frequency? and its importance

Answer

it ensures change of magnetic field
it produces varying magnetic fields

Is This Answer Correct ?

2 Yes

0 No

Question { 4770 }

I know current,volt,powerfactor of an electrical line. In
this line how I will calculate Active power and Reactive power

Answer

active power is V.I.cos(theta)
while reactive power is V.I.sin(theta)

Is This Answer Correct ?

6 Yes

1 No

Question { 14155 }

in our sub station why we step down firstly 33kv\11kv then
11kv to 430v. can we direct step down 33v to 430.v.

Answer

it will be dangerous as the transformers which converts 11
kv to 430 volts cant be installed in colonies

Is This Answer Correct ?

0 Yes

8 No

Question { KSEB, 8033 }

does over charging of a battery reduce its life?

Answer

yes

Is This Answer Correct ?

7 Yes

4 No

Question { TCS, 12620 }

what is frequancy

Answer

altering of value of current in cycles per second

Is This Answer Correct ?

3 Yes

5 No

Question { Ashok Leyland, 24174 }

wat happens if u use petrol in diesel engine

Answer

the petrol will not burn due to the absence of the spark plug

Is This Answer Correct ?

6 Yes

8 No

Question { 30477 }

what will happen when excitation of a synchronous machine
is suddenly reduce to zero when it is running at full
load..??

Answer

as the motor is in full load therefore it will stops
because the damper windings can not fulfil full load
requirements

Is This Answer Correct ?

2 Yes

5 No

Question { 5569 }

why we are using2 wave trap in a feeder?

Answer

we don't use wave trap in feeder, it's used in the GSS for creating connection between two GSS's.
actually we use the same power line for sending our voice and power both.

thus wave trapper is used to modulate our voice to the frequency of our power, i.e. 50 hz.

Is This Answer Correct ?

4 Yes

0 No

ghanshyam