Power Cable Selection

There are multiple factors which must be taken into account during calculating the cable such as;

1) What is the length of cable (>100mtrs de-rates the cable)?

2) How to lay, direct in ground or in open air? (temperature factor)

3) Are there any more cables in the route of this cable (grouping factor)

4) What is the max temperature of the area where it would lay?

5) Would the cable be armored or simple?

Hi,

If it's a motor use I=p/root 3*V*cosphi

FOR 850KW THE CURRENT CARRYING CAPACITY WILL BE 1500AMPS.SO YOU CAN USE 300SQMM OF ALUMINUM OF EQUAL LENGTH

What kind of machinery? Anyway, for normal load of 850KW, 415V, 50Hz, and PF = 0.8 :

I = 1480A

Icb(%age) = 1700A

The standard manufacturer size of CB = 2000A

And the cable size required would be:

11 X 1C X 630 mm^2 XLPE/SWA/PVC/CU + 2 X 1C X 300 mm^2 PVC/CU/ECC

:-)

Now again, you may also use a CB size of 1600A and the cables,

8 X 1C X 630 mm^2 XLPE/SWA/PVC/CU + 2 X 1C X 300 mm^2 PVC/CU/ECC.

But for machinery high inrush current, selecting CB of 2000A would be a better choice. It seems a little oversizd, though?

You have failed to mentioned the machinery type?