Underground Electricity

you would have to know how much current you will be drawing. then depending on the distance you will want to compensate with the correct gauge wiring. larger gauges are more expensive but allow for less resistance, inturn a smaller voltage drop across your AC line. look up a wire gauge table.

16mm x 1200meters

Theoratically there is no limit to the length of underground electrical cable.

An aboveground junction box is required at the end of each roll of electrical wire. Underground splices are not allowed and would be rather unwise.

The bigger the conductor area the smaller the voltage drop. If the cable is too small than the cable itself will become the circuit protective device (a "fuse"), in which case it will need digging up and replacing every time it blows, assuming it doesn't cause collateral damage or hurt someone in so doing...

This question was more or less asked in another thread. Fill in your data in the formulas. These formulas are made with the percentage of power loss in mind.

Ud = voltage drop
UL = line voltage
I = current
R = total resistance of cable
L = lenght cable
ρ (rho) = resistance per meter per square milimeter of copper wire (0,0175)
a = diameter (in mm²) of cable.

UL = 400V, I = 63A, L=630m

Ud = 400 x 4%

Ud = I x R

Ud = 63 x R

Ud = UL x 4%

R = (L x ρ) / a

UL x 0,04 = I x (L x ρ) / a

a x UL x 0,04 = I x L x ρ

a = I x (L x ρ) / UL x 4%

a = 63 x 630 x 0,0175 / 400 x 0,04

a = 63 x 11,O25 / 16

a = 43 mm² > in reality : 50 mm²

you need a cable of 4 x 50 mm² to run your motor(s)

are these all of the materials you need