Answer Posted / s. patel

the equation of Power:

P=VICos (phi)
for single phase:- if load is 128 kw for single phase
then...Iph=(p/vph Cos(phi)(assume:p.f=1)
= 128000/(240x1)
=533Amp so this need 400-500sq mm 1 core of copper ok...

and if 3 phase is there
then

p=1.73xVLxILxCOS(phi)
IL=128000/(1.73x415x1)
=178Amp

if it may p.f is down up to 0.85 then current rating will increase by 200 to 210 Amps

so we have to select the cable as per their current carrying capacity up to 210 amp for three phase connection.
So we have to select 95 sq mm x 3 core...ok

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