Interview Questions Answers in Electrical Engineering

Questions / { sanjay }

Questions Answers Category Views Company eMail

how is control wiring coding is done in a CRP panel ?

Genus, Havells, Hindustan Power Projects,

Electrical Engineering 1524

What is ideal IR values for ground and neutral.

Hindustan Power Projects,

Electrical Engineering 1280

Answers / { sanjay }

Question { HBL Power Systems, 129933 }

what is phase to phase voltage? what is line to line voltage

Answer

Line voltage and phase voltage depend upon connection, if the system is in star connection the line voltage and phase voltage will be equal while in delta connection the line voltage is 1.732 times of phase voltage.

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Question { 4151 }

our company have 750 kva oil transformer.still we have
facing a problem that is when voltage is 11.5 kv coming
from HT side then LT-side voltage is 420v or above at tape
1.please give me best solution to decrease the voltage.

Answer

File a case against the seller if transformer values are different than those mentioned on specification plate.

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Question { Suzlon, 9912 }

parallel operation for tansformer which condition fill fil
for that

Answer

following
1- KVA rating should be same
2- Voltage should be same and
3- frequency should be same

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Question { Super Max, 6588 }

What are the types of circuit breakers ?

Answer

Depending upon arc quenching method they are for types

Air cb
Vaccum cb
Oil cb
SF6 cb

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Question { 3411 }

HI, I want to buy a new Xformer to my plant. what are the
main parameter should I check ( Xformer rating is 16 MVA)

Answer

The MVA Rating here shows that you require a transformer which converts 11 kv to 66 kv. If you want to buy such a heavy transformer , then the seller will itself provide all the details

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Question { 4871 }

1. What is differential relay? How it operates?

Answer

Diffrential relay is used in transformer winding protection, it calculates the current of secondary side with transformer turn ration, if the current on other side is very slightly diffrent it does not trip but when iy crosses a fixed percent of defined protection it trips the circuit.

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Question { 5652 }

If a ACB breaker is tripping and closing problem, then what will we check internal..?

Answer

Check the overload current settings, and also check if any cable is faulty or grounded?.

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Question { 13665 }

What is phase in electrical engineering?

Answer

Phase is vectorial representation of line voltage like
Vsin@

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0 Yes

1 No

Question { 5345 }

why do transformer make a sound

Answer

it is due to magnetisation and demagnetisation of core according to friquency and voltage.

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Question { Bhel, 10272 }

Why transformer rating is represent in KVA?

Answer

Because the only thing which doesn't change both side is multiplication of voltage and current. So if any one can calculate the other side values if he have n1 : n2 ratio and any 1 value, ie voltage or current.

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Question { NTPC, 7918 }

why do mostly prefer to generate and distribute electricity in 3 phase..not in 4 phase or 5 phase.??

Answer

The power generates due to change of flux passing through armature, in 3 phase system the displaced flux at equal angle gives max output without hindering other flux path. That is why 3 phase generation is in practice. It is also very economical.

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Question { Standard Chartered, 3236 }

What is the inside of ACB & VCB & SF6 breaker's pls tell me about this

Answer

Above answer is correct , but acb is used for voltage less than 1100 v, vcb is used for voltage less than 33kv and sf6 breaker is used for voltage above 33 kv.

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Question { Rancho, 2424 }

circuit breaker is ...............connected with circuit

Answer

faulty current protection device

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Question { 3227 }

why ground cannot be used as neutral as ground also provides close path for current flowing ?

Answer

the ground has always zero voltage with zero resistance, so if we connect any voltage it will draw huge current. But neutral has some resistance which balance the current flow .

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2 Yes

1 No

Question { Modern Terry Towels, 2056 }

i have ht transformer of 142 kva with air cooled facility,having secondary voltage 7850volt, and secondary connected full way bridge rectifier .i faced the problem repeatedly that transformer one coil and rectifier diode of two phase was burnt two times. i checked all the secondary ckt. no any short ckt found,then what will be the cause side

Answer

First open all the cables and take megger of all cables , there must be some earthed cable which is causing this problem.

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1 Yes

0 No