Electrical Engineering Interview Questions
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I have 480V Single phase and I am trying to figure how big of a transformer (KVA's) and Primary breaker size I need to provide 200 Amps at 240V for a building.


1 791

what will happen when power factor is leading in distribution of power?

Power Grid, AMET, JTO,

10 14862

In CDG type IDMTL realy O/L , E/F, O/C which are used for out going feedrs,on R-phase o/c element, Y-phase , e/f elecment and on b -phase o/c element will be connected . Why the earth fault on center phase only, why not on other two phases?

2 6752

which fault is severe and why?between lll fault and lllg fault which fault is severe and y?



what happen if we give 220 volts dc supply to d bulb r tube light?


9 16239

suppose generator rating is 50 kw,load is 25 kw,hw much d generator ll generate?what about d remainin power?


2 3006

if d gen is 50kw,load is 60 kw,hw d gen ll supply d remaining power?


3 2536

What is the significance of vector grouping in Power Transformers??

3 4015

how we do Vector group ,magnetic balance and tap changer test in Transformer?

HPL, BSL, Afcons,


which type of motor is suitable for water suction pump ?

4 3077



6 26229

for 5KW resistive load can anyone please suggest me whether to go for UPS/Inverter or Generator depending upon cost calulations


Define motor & pump?

3 7933

I am designing new project sub station with 220 kV / 11 kV, 40 MVA capacity. This project have many recifier sets, which can generate 3rd harmonics. Now I have to select vector group of This transformer. To minimise 3rd harmonics, what care should I take in selection of Transformer Vecrtor group? If it is Y-Y with open Delta tertiary then what should be the rating & voltage of Tertiary Winding?


why we not connect the 12 V batteries in parallel to get the more backup supply for an UPS ? wheter off line or on line UPS ?

2 2356

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Un-Answered Questions { Electrical Engineering }

how can I calculate charging current of cable/overhead conductor? what is roll of voltage in it ?


what is self capacitance of inductor


what size steel armoured cable is required to support 1500kva capacity. would 70mm squared be enough or would I need 90 or 120mm squared 3c plus earth


. How to calculate the Short Circuit Impedance in Transformer? How to calculate the Short Circuit Impedance in Transformer?


can anyone give an idea about dia calculation in cold rolling mill


what is the step by step formula for calculating bus bar phase and neutral size of a panel board.suppose the incomer of panel board is 100A..???step by step answer please


What is mean by STUB protection?


We need to current density & short circuit calculation at 65kA for aluminium & copper busbar.


Name of the relay of low lub oil presuure in DG sets


how hazordious area is classified at an oil & gas plant and categorise suitable class of electric equipment in that area like induction motors, LCS, Lighting Fixtures Fluerescent/Flood lights Mercury& sodium lights, J.Bs, Power Cables etc


In constant power region of 3-phase IM torque-speed characteristics, if frequency increases slip A does not alter B decreases C increases D none of above


This is reqd for a 1MW Solar power plant..We have 2DC outputs from the solar panels Connected to 2INVERTOR panels.. Output from invertor is 3ph,280v,500kva,50hz.These are connected to individual ACB.This has to be stepped up to 11KV ,1250KVA SYSTEM.Now can I use (1) one more ACBTO GIVE A COMBINED OUTPUT OF 1000KVA,280V & STEP UP THE OUTPUT BY USING a single two winding 3 ph transformer 11kv/1250kva. or (2)use the two outputs and connect to one three winding transformer of above rating..Pls suggestwith details.


is it possible to have dc motors on single chip


What is the lower limit of break-down voltage of converter transformer.


Control wiring of a dol starter for forward and backward