Answer Posted / guest

whats the basic concept is to provide accurate protection
against fault for the system!
for alternator:
to do so we need to consider the extreme part from top of
the phase to neutral (as potential near neutral and earth is
low the most chances of such fault is to occur near the
neutral). now if the fault occurs near the neutral point,
the covered winding between the fault point and neutral
produce small magnitude of the fault current;
to measure that small signal current we require extreme
sensitive relay system!
if we use such then it ll also detect the unnecessary faults
such as inaccuracy of C.T or saturation of C.T etc. to avoid
malfunction: this is the reason why we protect only 80 to 85
% of winding and left 15% of winding from neutral side
unprotected!
so only the differential protection is not suffice!!
REF: to protect this remaining 15% we need other type of
earth fault protection scheme(neutral connected through
resistor or neutral connected via transformer)! (restricted
earth fault protection is designed to 15% of rated phase
current)

what is the difference between STAR and DELTA connection and application wise how it can be utilizedd

1737

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can u tell me the promotion from oiller to enginer

1428

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percetans

1713

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1.how many earth pits are required for 1000 k.w plant include substion , transformer ? 2. how many earth pits are required for 500kva generator.what is formula to calcute?

2295

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how can decide the current rating of oltc

1864

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What are the advantage of free wheeling diode in a full wave rectifier?

650

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is it possible for different brand of H.V transformers to run or operate in parallel to each other? if so how much disturbance can this affact the H.V bus bar?

1649

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we have earthmat at 110KV substation.we would like to take earth resistance.b some says that by connecting earth megger terminals (C1,P1) at middile point of earthmat (at riser) will cause voltage gradient at other earthmat nods and dont get exat earth resistance.when connecting at end nods will get exat value . is it correct .please explain

1723

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what is the significance of terminal voltage and phase sequence in the operation of paralleling of two generators?

2024

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how r charge carriers produced

1635

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sir, what is the importance of Fault MVA. how to calculate fault mva of 33kv substation connected by 6.5 km line(single circuit with equal spacing) with 110/11kv transformer in 110kv susbstation.the fault mva on 11 kv bus in 110kv susbstation is 208mva.

2489

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How we calculate the size of ht cable for any transformer

1562

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star delta starter contorl circuit... drawing..

1670

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how many parameters can integrate with fire alarm basically ?

1497

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give single line diagram of D.G distribution form alternator to main L.T panel?

7039

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