Interview Questions Answers in Electrical Engineering

Question { SCPL, 2789 }

We are installing a 1.6 MVA transformer at our crusher plant and the feeder of HPSEBL is 2 km away at substaion .
and a VCB is installed in the substaion which is 2 km away from transformer so we need another VCB near the transformer.

Answer

VCB in the MUSS is for line protection and you need another for transformer protection

Is This Answer Correct ?

3 Yes

0 No

Question { 2361 }

In D O l starter motor starts as a star connected ,then in star delta starter also motor initially starts as star how come star delta is preferred from dol

Answer

Instead of bulbs voltmeters can be employed

Is This Answer Correct ?

0 Yes

1 No

Question { Ofer, 2353 }

How to parallel a alternator without using synchro scope or lamp methods

Answer

Use voltmeters instead of lamps

Is This Answer Correct ?

1 Yes

0 No

Question { Techno Electric and Engineering, 8645 }

What is purpose of APFC panel?

Answer

It maintains the set pf

Is This Answer Correct ?

4 Yes

0 No

Question { College School Exams Tests, 3135 }

Why there is restriction to generated voltage to certain limit for example (now 18kv) ?

Answer

Insulation

Is This Answer Correct ?

2 Yes

0 No

Question { 7852 }

In Energy meter How many rotation Equal to one unit.

Answer

It is given on the dial / nameplate

Is This Answer Correct ?

9 Yes

2 No

Question { MSETCL Maharashtra State Electricity Transmission Co Ltd, 4823 }

Why battery rooms painted with dark colour

Answer

Mainly ,to absorb the heat generated

Is This Answer Correct ?

18 Yes

2 No

Question { Roman, 2984 }

What is balance beam relay ?

Answer

1 distance relay 2 Battery over current relay - Voltage vs current

Is This Answer Correct ?

1 Yes

0 No

Question { 3278 }

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

Answer

Earth resistance can not be made as low as that of conductor economically .

Is This Answer Correct ?

1 Yes

1 No

Question { Wipro, 2003 }

I need to calculate the Battery bank back up for below configuration:-
UPS - 120 KVA
Battery Bank - 200Ah
Volt of each cell - 12 V
Total No of cell - 34 No's
Can you please help me to get the battery back up time for above configuration...? along with formula

Answer

Energy stored in each battery = 12 x 200 WH ( VAH) ,total stored energy = 12 x 200 x 34 WH . Divide this by load in W to get ' Back up time' in hours (approx)

Is This Answer Correct ?

0 Yes

0 No

Question { Metro, 4095 }

how to check the continuity of a cable with a megger

Answer

Do not check continuity with megger , use multi meter

Is This Answer Correct ?

0 Yes

0 No

Question { 2028 }

How to calculate percentage impedance of a power transformer.

Answer

(Irated x Z / Vrated )x 100

Is This Answer Correct ?

1 Yes

0 No

Question { 2052 }

why we earth only one side of a power cable. And which side is advisable to earth.

Answer

Only one side of armour is earthed to avoid circulating current in the armour

Is This Answer Correct ?

0 Yes

0 No

Question { BWSSB, 1943 }

When PRV operated at power transformer ,can anybody tell me particular pressure for 50mva transformer plzzz.

Answer

PRV is provided to prevent tr from bursting due to the internal pressure . It could be from 0.4 Kg/cm2 to 4 Kg /cm2. The older tr s had explosion vent with copper foil

Is This Answer Correct ?

0 Yes

0 No

Question { 2093 }

difference between local breaker backup relay or backup protection relay ?

Answer

LBB relay is for failure of breaker to trip , and back up protection relay ( usually EM ) is for failure of main relay ( usually electronic )

Is This Answer Correct ?

0 Yes

0 No

k.prakashchandra