Hi voltage power transmission

[thinfourth2]

Way back when i was at school i was taught that higher voltage is better for moving power.

To make this easy we use AC

Today i heard that they re now using high voltage DC on subsea lines from wind farms


So without the normal wind power will destroy everything

Why are they using DC instead of AC

[thinfourth2]

Max_Torque said:

Fundatentally, the efficiency of "high voltage" is actually one of "low current". Where wire and transmission systems have resisitive losses, and the power lost to heat is IsquaredR. So as current goes up your losses go up as the square. For a given power, the lowest current is achieved with the highest voltage. The reason for AC is really to enable cheap and simple passive transformers to be used to, er, transform between various voltages as required. DC voltage level transfers are much more difficult to do. So apure DC system has to compromise on it's peak transmission voltage, to a level that is still usable at the comsumer end (because no easy DC transformer exists), whereas an AC systen distribute at say 400KV, and then step down in stages to the 240V we use domestically.

So they are using DC as AC is cheaper and easier