Interview Questions Answers in Electrical Engineering

Questions / { ashok reddy reguri }

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In IDMT RELAY the term minimum (M) indicates what?

7 Electrical Engineering 10005

Answers / { ashok reddy reguri }

what is a relay?

Answer

relay is a sensing device.
when the fault occurs more current flows thro the relay coil
produces sufficient field to attract circuit breaker
contacts,so that ckt is opened

Is This Answer Correct ?

2 Yes

2 No

Question { 24101 }

ON WHAT BASIS LOADS ARE CLASSIFIED AS RESISTIVE,INDUCTIVE
AND CAPACITIVE LOADS?.GIVE PRACTICAL EXAMPLES FOR EACH

Answer

they r classified based on the response of the element to
alternating voltages or currents(e.g inductor will oppose
the change in current so it allows voltage first and then
after 90 degrees it allows current to pass thro it
resistive loads- heaters, owens
inductive loads -induction motors
capacitive loads-synchronous condensors,capacitor banks

Is This Answer Correct ?

21 Yes

2 No

Question { 10654 }

What about Reactive power.and role of that one?

Answer

reactive power is the power absorbed by the reactive element
If ac power is required to be transferred there must be
reactance,there must be reactive power.
power transferred p= (EV\X)sin(delta)
so for power transfer we have to see that reactive power
must be present and for transferring more active power we
have to see that reactive power must be minimum.

Is This Answer Correct ?

3 Yes

1 No

Question { Bhel, 20207 }

Why current flows in nutral? As per theory there should be
no current in 3 ph explain.

Answer

In single phase systems current flows thro the neutral as
it is the return path
In three phase systems w.r.t individual phases there is
neutral current .(Ir0,Iy0,Ib0)
For balanced system Ir0+Iy0+Ib0=0
For unbalanced system Ir0+Iy0+Ib0 not equal to zero

Is This Answer Correct ?

4 Yes

0 No

Question { 75741 }

what is the function of a starter in a motor?
explain RLC circuit.

Answer

Function of starter is to limit the starting current and
make the motor start in a desired and safe way.
For dc motor we can go for resistance starters(3-point,4-
point)
For 3phase induction motors we can go for
DOL STARTING ,STAR DELTA STARTING,RESISTANCE STARTING,AUTO
T\F STARTING.

Is This Answer Correct ?

41 Yes

10 No

Question { L&T, 67530 }

what is the difference between power and distribution
transformer?

Answer

power transformer generally operated at full load. Hence,
it is designed such that copper losses are minimal.
however, a distribution transformer is always online and
operated at loads less than full load for most of time.
Hence, it is designed such that core losses are minimal.

Is This Answer Correct ?

125 Yes

5 No

Question { 27931 }

why current increases when voltage decreases in ac
system

Answer

current increases when voltage decreases in any system at
the condition that KVA is constant

Is This Answer Correct ?

12 Yes

5 No

Question { 16748 }

what will happen when choke in tube light circuit was not
working???

Answer

For the tube light to turn on an initial surge is required
which is produced by the choke
if there is no choke tube light will not turn on
Anothe purpose of choke is to limit the current during
running conditions.it will not serve the purpose

Is This Answer Correct ?

8 Yes

1 No

Question { APGenco, 78656 }

what happen when dc shunt motor field is sudden open in
running condition

Answer

When field ckt is opened field current will be zero,flux
will be zero,as speed is inversly proportional to speed
becoz of zero flux motor tries to rotate at maximum
(infinite),dangerous speed .motor will be damaged(un rooted
etc..)

Is This Answer Correct ?

72 Yes

12 No

Question { 26957 }

what is the frequency standard with tolerance level for India?

Answer

50 hz is the standard frequency
with a tolerance of +\- 1.5

Is This Answer Correct ?

16 Yes

5 No

Question { NTPC, 75811 }

what is the function of a commutator in a dc generator?

Answer

its function is like a rectifier(ac to dc converter)

Is This Answer Correct ?

53 Yes

9 No

Question { 36126 }

how we are measuring the winding temperature of the
transformer?

Answer

sumpners test

Is This Answer Correct ?

14 Yes

13 No

Question { 32635 }

what is the higest transmission voltage and generated
voltage in india

Answer

765 KV TRANSMISSION VOLTAGE
21 OR 22 KV AT RAMAGUNDAM (CLARIFY PLEASE)

Is This Answer Correct ?

15 Yes

5 No