Question { MEIL, 411516 }

I want formula to calculate cable size as per load given in
kw & amp.I searched many sites but didn't right answer.Plz
reply me asap.

Answer

as u know power=v*i*power factor
the load is given in KW
SUPPOSE THE LOAD IS 30KW
FOR THREE PHASE VOLTAGE IS 440V
THEN, 30*1000=440*I*O.9(SUPPOSING PF)
30*1000=396*I
THEN, I=75AMP
FOR ALUMINIUM CABLE 1Sq.mm=1.5 amp of current
for copper cable 1sq.mm=5 amp of current
then, your cable size is 15sq.mm for copper cable