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 Bhel aptitude test questions  Bhel Aptitute Test Questions (6)  Bhel placement papers  Bhel Placement Papers (3)  Bhel technical test questions  Bhel Technical Test Questions (23)  Bhel interview questions  Bhel Interview Questions (59)
 
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Question   HOW TO FIND OUT 1. LINE CURRENT, 2. PHASE CURRENT IN AN ALTERNATOR / TRANSFORMER WHICH IS FEEDING A I)STAR LOAD ii) DELTA LOAD, USING A CLAMP METER. NORMALLY WHEN WE USE CLAMP METER IN A DG SET THEN WHAT DO WE GET?? PHASE CURRENT OR LINE CURRENT. Rank Answer Posted By  
 Interview Question Submitted By :: Vivek
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Answer
line current means the current flowing through the AC 
supply lines.phase current means current flowing through 
each phases like R or Y or B phases.relation between line & 
phae currents are 

star connected system: phase current =linecurrent
delta connected system: phase current ={ linecurrent/√3}

for balanced 3Ф 4W system current flowing through the 
neutral will be sum of phase currentsand will equal to zero.
ie Ir+Iy+Ib =0 =In
 
0 Sudheer
 
 
Answer
dear sudheer, the question was to find it out practically, 
as i wrote, using the clamp meter ..... theory we all know 
but thequestion is how to apply the knowledge .... let me 
ask the question in a different way..... where exactly 
would u put the clamp meter in order to measure the line 
curren and phase current?? because phase current passes 
through the neutral and the line current through two 
phases. .... so i guess one might need to open theload or 
the source especially in order to measure the phase 
current ....if anybody knows a link from where i can get 
practical knowledge like this then pl let me know.... 
thanks.
 
0 Vivek
 
 
Answer
u can find the phase current from the CT out going. then u 
calculate the line current herewith
 
0 Rahul
 
 
 
Question   what is the capacitance of a single conductor Rank Answer Posted By  
 Interview Question Submitted By :: Ram
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Answer
The capacitance of the single conductor depends on size and 
length
 
0 Swetha
 
 
Question   What is the function of Lightning Arrester & Wavetrap in Power system ?? Rank Answer Posted By  
 Interview Question Submitted By :: Crmeena
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Answer
Wave Trap,

This is varying the impedance...

The Application is PLCC(power line career communication)

Linghtining Arrester:

This is grounding the surge voltage.....
 
0 Sivasamy83
 
 
Question   how percentage impedence effect on the size of the power transformer? Rank Answer Posted By  
 Interview Question Submitted By :: Jraj
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Answer
% impedence is use to determine the max fault current the 
transformer is capable of delivering to a downstream short 
circuit. 
Fault current=FLC*100/%imp.
this fault current is use to cal fault MVA 
Fault MVA = 1.732 x fault current x V.

eg: If transformer of 2000kVA,5%imp having flc of around 
1200A is use to supply to a motor of same flc carrying 
capacity and if the voltage drop at transformer terminal is 
more than the permissible voltage drop (+- 10%)during 
stating of motor then the above transformer will be of 
lower rating hence we have to select the transformer rating 
higher than 2000kVA eg:-3000kVA (In other words transformer 
having higher SC current capability ).If voltage remain 
within the rated voltage of the motor then no oversizing of 
tranformer is required.
 
0 Jaswinder
 
 
Answer
hieght of winding effect on impedane
 
0 Akr
 
 
Question   What is the acessaries distribution transformer ? Rank Answer Posted By  
 Interview Question Submitted By :: Rajkumar Pal
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Answer
radiator,conservator,breather,buchozrelay,hvwinding,lvwindin
g
 
0 Guest
 
 
Answer
conservator,radiator,hv wdg, lv wdg,tap changer,buchoz relay
oti relay, wti relay
 
0 Chetan
 
 
Answer
CONSERVATOR,RADIATORS,BUCHCHOLZ RELAY,WTI CT,NEUTRAL 
CT,PRESSURE RELIEF VALVE(PRV),MAGNETIC OIL GUAGE
(MOG),THERMOBULB,DRAIN VALVE,FILTRATION VALVE,SAMPLING 
VALVE....
 
0 Giri
 
 
Answer
Accessories of Distribution Transformers are
1. Conservator with oil level Indicator,
2. Silicagel Breather filled with blue silicagel.
3. Oil Temperature Indicator
4. Winding temperature Indicator
5. Buccholz Relay
6. HT & LT Bimettalic clamps/ incoming & outgoing terminals.
7. Tap Changer if required.

 HT/LT Windings, valves,are part of Transformer & tank .
 
0 Zahid Noor
 
 
Answer
Accessories of Distribution Transformer are-
Conservator,magnetic oil guage, oil guage, filtering & 
drain valves, sampling valves, gaskits,marshaling box, hv 
cable box, lv cable box, hv & lv bushings, neutral bushing, 
Buccholz relay, feed pipe assembly, hv busbar, lv busbar,i. 
e incoming & outgoing terminals,  thermobulb, pressure 
relief valve (PRV), Winding temp.indicator, oil temp. 
indicator, neutral ct. radiator, breather filled  with blue 
silica gell, transformer wheels, hv wdg, lv wdg, Tap 
changer.
 
0 Sabale.dnyaneshwar@gmail.com
 
 
Answer
1.Tank with Radiator
2.Conservator with top cover
3.core
4.core channel and base channel
5.cotton tape and webbing tape
6.lv and hv coils
7.runner and dove tail runner
8.earth foil
9.MPC wire
8.kraft paper
9.transformer oil
10.press board
11.tie rod
12.clamping rod
13.muts and bolts
 
0 E.saravanan
 
 
Answer
Tank with Radiator
2.Conservator with top cover
3.core
4.core channel and base channel
5.cotton tape and webbing tape
6.lv and hv coils
7.runner and dove tail runner
8.earth foil
9.kraft paper
10.transformer oil
11.nuts and bolts
 
0 Shashikant
 
 
Answer
BUCHOLZ RELAY, WINDING/OIL TEMP INDICATORS ETC ARE SEEN ONLY
IN POWER TRANSFORMERS. IN DISTRIBUTION TRANSFORMERS, THERE
WILL BE TR. TANK WITH CONSERVATOR, BREATHER, BUSHINGS ETC.
PROTECTION IS PROVIDED WITH D.O. FUSE IN PRIMARY AND
ORDINARY PORCELAIN FUSE IN SECONDARY. PROTECTION AGAINST
LIGHTNING IS PROVIDED THROUGH LIGHTNING ARRESTORS.
 
0 Sanoj
 
 
Question   What type of motor is used inside computer CPU. Rank Answer Posted By  
 Interview Question Submitted By :: Manmohan Mahapatra
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Answer
high speed spindle motor
 
0 Ree
 
 
Answer
stepper motor
 
3 Pradeep
 
 
Answer
only stepper motor used
 
0 Sanjay Chaudhary
 
 
Answer
ac servo motor is used
 
0 Niranajn
 
 
Answer
stepper motor becoz stepper motor rotation(step) can be 
contoled accordingly.
 
0 Adesh Bandhu
 
 
Question   if any body selected in bhel et oct 08'pl tell me how to be selected Rank Answer Posted By  
 Interview Question Submitted By :: Guest
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Answer
i hav joined bhel as et in nov 2008.
u should write ur branch, only then one can advice u what 
to do n how.my branch is civil so i can advice u on civil. 
but if u hav other, i will ask my frn 2 help u.
 
0 Lalit Kumar
 
 
Question   a 3 phase motor was running with delta connected, suddenly one phase winding got burnt off, what will be the effect ? Rank Answer Posted By  
 Interview Question Submitted By :: Rvg
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Answer
the effect ---single phasing...  motor oveload protection 
or MCB will trip  and open the circuit.
 
0 B.v. Reamon
 
 
Answer
delta connected winding, one winding burnt off means, its 
open circuited. So the motor will work as open delta system 
and run normaly with non uniform torque.
The max. load that can carry will be reduced to 57.7% of 
full load.
If the motor is connected through a phase faliure relay, 
the relay will trip the total ckt.
 
0 Rvg
 
 
Question   why motor starting current is High ? Rank Answer Posted By  
 Interview Question Submitted By :: Rvg
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Answer
at starting rotor is stationary, due to its inertia it will 
require more torque to rotated and torque is proportional 
to armature current
so requires more starting current
 
0 Gajanan
 
 
Answer
Dear Mr. Gajanan, as you are dealing with more machineries, 
i want to stress some points:
During starting of motor:

the armature(rotor) is stationary, and it does not having 
any magnetic property to resist the applied rotational 
frequency at that time.

so it will act as a conductor fixed at rotating magnetic 
field and produce some eddy current loss, and with in short 
period of time, it will develope some anti rotional effect 
to resist the rotational field, ie: rotating with same 
direction to reduce the eddy curent.Thats why after 
starting current reduces.

inertia of the rotor also having some major role on the 
starting current. The gap between rotor and stator having 
role on the starting current and initial power factor.
 
0 Rvg
 
 
Answer
as in the initial conditions the motor is at rest,the speed 
of the motor is zero.
           
        using KVL equation,
                           V=Eb+IaRa,Eb=back EMF
                                     Ia=armature current
                                     Ra=armature resistance
(very small),V=input supply(around 220V dc)
      Initially speed=0
    implies Eb=0
      Ia=(V/Ra)   which is very high value,since V is high 
and Ra is very small.
            Hence starting resistance or 3 point starter 
are used.
 
0 Y.v.vsurya Teja
 
 
 
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