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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. |
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Answer Posted By |
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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 |
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| 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 |
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| Answer |
u can find the phase current from the CT out going. then u
calculate the line current herewith  |
0 | Rahul |
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| Question |
what is the capacitance of a single conductor |
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Interview Question Submitted By :: Ram |
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The capacitance of the single conductor depends on size and
length  |
0 | Swetha |
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| Question |
What is the function of Lightning Arrester & Wavetrap in
Power system ?? |
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Answer Posted By |
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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 |
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| Question |
how percentage impedence effect on the size of the power
transformer? |
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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 |
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| Answer |
hieght of winding effect on impedane  |
0 | Akr |
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| Question |
What is the acessaries distribution transformer ? |
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Interview Question Submitted By :: Rajkumar Pal |
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| Answer |
radiator,conservator,breather,buchozrelay,hvwinding,lvwindin
g  |
0 | Guest |
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| Answer |
conservator,radiator,hv wdg, lv wdg,tap changer,buchoz relay
oti relay, wti relay  |
0 | Chetan |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| Question |
What type of motor is used inside computer CPU. |
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Answer Posted By |
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Interview Question Submitted By :: Manmohan Mahapatra |
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| Answer |
high speed spindle motor  |
0 | Ree |
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| Answer |
stepper motor  |
3 | Pradeep |
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| Answer |
only stepper motor used  |
0 | Sanjay Chaudhary |
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| Answer |
ac servo motor is used  |
0 | Niranajn |
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| Answer |
stepper motor becoz stepper motor rotation(step) can be
contoled accordingly.  |
0 | Adesh Bandhu |
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| Question |
if any body selected in bhel et oct 08'pl tell me how to be
selected
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Answer Posted By |
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Interview Question Submitted By :: Guest |
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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 |
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| Question |
a 3 phase motor was running with delta connected, suddenly
one phase winding got burnt off, what will be the effect ? |
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Answer Posted By |
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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 |
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| 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 |
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| Question |
why motor starting current is High ? |
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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 |
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| 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 |
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| 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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