Answer / rvg

The most frequent faults are short ckt faults and earth
leakage faults and insulation breakdown.. Due to these,
some part of the cable( specifically, underground) get
heated up and burst.
Locating such faults, some wheastons bridge system can be
used.
2. the earth wire above the conductor can protect the live
conductor from lightning surges.up to 30 deg.down max it
can protect from horizontal level. In distribution system
normaly does not require bcz the height of such post may be
as small as 11 mtr, but that of 33kv or 220kv may be as
high as 28 or 35 mtr.
3.transmission losses are copper heat loss and corona loss
and insulation loss.( refr Power system by UPPAL)
4.6-12%

Answer / rahul maddineni

1)The most frequent fault in under ground cables is Short
circuit(phase to phase)due to insulation layer gets heated
and burst.It can be tested by using Megger and fault
locatoin can be detected by Cable Detector.
2)Earth wire will protect the conductors from Lightening
surges and it provide the low resistance path for the over
currents during lightening.
3)Transmission losses are a)I^2R losses b)Corona losses.
4)May be 5% to 10% and also depends up on the type of alloy
of material

Answer / akhil

1)i think that line to line faults happen in cables.by
noting the variation in current reading we can locate the
faults.



2) to save insulators and also to make insulators effective
between line and ground.

to save cost ,as providing earthing(coal & salt) to
particular tower for huge current is costly.
also huge current (in case of short circuit)can charged the
surrounding area.
how much area it can protect ? elabrote
3) refer some book

4) 8-10%

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