Interview Questions Answers in Electrical Engineering

Questions / { deepak mishra }

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Answers / { deepak mishra }

what is the differance of acb and mcb and mccb

Answer

mcb-miniature circuit breaker- 6amp to 63amp
mccb-moulded case circuit breaker- upto 1600amp
acb- air circuit breaker- above 1600amp
regards deepak

Is This Answer Correct ?

3 Yes

5 No

Question { 17374 }

why we cant use AC supply products in DC supply?

Answer

we can use pure resistive circuit to both ac and dc supply
but in case of induction type instrument we cant use dc bcz
induction principle is applicable to only ac. example are
induction motor and transformer

Is This Answer Correct ?

0 Yes

0 No

Question { HSL, 8853 }

What is the acceptable earth resistance for Commissioning
the Transformer?

Answer

as per IS it should be less than 5Ohm

Is This Answer Correct ?

1 Yes

1 No

Question { 6778 }

What happens if ac is applied to dc systems and vice versa?

Answer

if dc supply is given to ac system than equipment like
transformer and motor(which works on induction principle)
burns. it is due to so much heat generated in windings as
flux does not vary in dc supply. while giving ac to dc
system there will be a increse in losses and material.

Is This Answer Correct ?

6 Yes

0 No

Question { 4486 }

what will happen if field winding supply of synch generator
accidently got disconnected?

Answer

if field winding is disconnected then generator is not
build up bcz there is no any flux in the air gap so no flux
will be cut by armature conductor and at the same time no
emf will be induced
i think raghavendram wrong bcz obove condition occur when
prime mover is disconnected and excitation remains on..

Is This Answer Correct ?

1 Yes

0 No

Question { Divis Laboratories, 8628 }

how much cuurrent flow through human body effected ????

Answer

above 9mA cane cause sensation to human body

Is This Answer Correct ?

0 Yes

0 No

Question { A2Z Group, 5429 }

Why does not AC excitation use in rotor of AC Generator
instead of DC excitation?

Answer

actually in rotor of ac generator we require fixed
alternate north and south pole for generation of ac, theese
are electomagnet.theese poles are acheived by direct
current bcz in case of ac pole changes there polarity in
each half cycle.

Is This Answer Correct ?

1 Yes

0 No

Question { 4215 }

what is the working principle of induction motor

Answer

i am adding just one thing additional to above statement-
torque will produce and as per lenz law the rotor rotates
in the same direction as the rotating field.

Is This Answer Correct ?

1 Yes

0 No

Question { 3596 }

why in an electrical lab a bulb connected to supply goes off
slowly when the main supply is switched off?

Answer

in our electrical system alwys there is capacitance as in
case of capacitor. it is well known, capacitance is the
electric charge storing capacity, actually it store
electric energy in the form of electric field.
when switch is off then this stored energy is discharge so
bulb goes off slowly. but remember this stored energy is
too less.

Is This Answer Correct ?

1 Yes

0 No

Question { Oil India, 5591 }

What is the maximum load an electric engine can pull??

Answer

i think your question is not a complete one, as the load is
decided by the motor rating and and no. of moter connected
and there arrangement.

Is This Answer Correct ?

2 Yes

0 No

Question { 4542 }

What is single break or Double break related to MCB?

Answer

in double break mcb both phase and neutral are disconnected
from the mains

Is This Answer Correct ?

5 Yes

2 No

Question { 4554 }

Can we use same copper cable for both AC & DC power.

Answer

it basically depends on area of aplication suppose in dc
transmission line we are using cu cable but for same
voltage in ac transmission we require more cross sectional
area as there is skin effect and lossed are more. while in
simple circuit like lighting we can use same cu wire.

Is This Answer Correct ?

7 Yes

0 No

Question { 3840 }

Why used in netural grounding transformer for netural side

Answer

nutral is grounded for balancing of current. in case when
there is leakage in equipment and if it is earthed then
circuit will complete through neutral grounding.

Is This Answer Correct ?

8 Yes

1 No

Question { 3808 }

what is the slip of synchronous motor

Answer

actually slip is there in case of induction motor and it is
(Ns-N) the difference b/w the synchronous speed and the
actual speed of motor.
as synchronous motor run always with synchronous speed so
slip is Zero in case of synchronous motor.

Is This Answer Correct ?

18 Yes

0 No

Question { 5212 }

which metal is use in shunt

Answer

manganin metal is used in the instrument shunt.

Is This Answer Correct ?

3 Yes

1 No