Suppose load is 100KW, length 50m, how to calculate cable size. If we know current Is any easy mathod to calculate cable size.
15 MT length 2x1.5mm how much Kw ?
Cable sizes aren't easily calculated. That's why standard sizes appeared ; like NEC IEC. You can search for tables of standard size of cables in the internet. For the above case, I think u'll have to use 3 phase circuit. So Calculate the current in each phase then accordingly get the corresponding cross section area from the standard table. Anyway, here below I found a table for you. : Cross section area (mm2) Amp (A) 2 10 315 4 22 6 28 10 35 16 42 25 65 35 80 50110 Don't blame me if it blew up :)
There are two issues to consider, cable heating and voltage drop. Of the two, voltage drop is by far the easiest. You need to determine what the allowable voltage drop in you cable is. The voltage drop is just I x R where I is the current and R is teh round trip cable resistance. The specification of 100 kW isn't enough. If its a high tension 100 kV line, the current is only 1 amp and a run of 16 AWG wire would deliver about 99,999 volts out of the original 100,000 volts to your load. If its a 100 volt system then a 4 AWG wire would only deliver only 20 volts to the load. The formula for wire resistance (in AWG) is that 10 AWG has 0.001 ohm/ft. Each increase of 1 in the gauge increases resistance by the cube root of 2 (about 25%). You calculate by picking what voltage drop you can live with, for the known current figure the resistance, knowing the length figure the resistance per foot, and then pick the AWG using the above. The second concern is wire heating. Although you could do the heat transfer calculations, instead look up the allowable ampacity for any wire in an electrical engineers or NEC handbook.
