what is the procedure for cable sizing or on what basis we
will calculate the size of cable?????

Answer Posted / raghavendran.r

Thanx to all for giving useful answer on that subject.I
would like to add that cable selection is also influenced
by certain factors like the Derating Factor.

A cables Current carrying capacity is reduced by the
following factors

a) Soil thermal resistivity.

b) Grouping Factor.

c) Ambient Temperature factor.

d) And the Depth at which Cable is to be laid.

Based on All these factor the current carrying capacity is
calculated and that also decides the number of runs of
cable to be laid.

Apart from this what Mr Matharu has stated is taken care of.

Formula to calculate SQMM is

Max short Ckt withstand current*sqrt[T(fault time)] /K.

for EX = 40 KA*sqrt(.25)/(.0928)

Is This Answer Correct ?    4 Yes 2 No



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