High voltage DC lines are typically over head.
Capacitance is why all long distance lines are above ground. If they were under ground the wire insulation would absorb so much energy on a 750kv, 60Hz system that only after 25 or 26 miles no power would make it to the other side of the line. The lines capacitance would equal the transmission capacity at that distance.
Brazil currently has the longest DC transmission line. Something like 600 to 700 miles with almost no line loss.
The old solution was to use 25Hz for long distance transmission and rotary convert it back to 60Hz. But with better cheaper faster electronics converting very high voltage DC back to AC isn't a challenge like it was 30 or 40 years ago.
Quote:
Originally Posted by UFO
It's not necessary to move power that distance.
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You are correct, there should be no need to move power that distance, but when a (failed) government refuses to build power plants within a very large state, voilą stupidity prevails and demand is created for that which defies logic.
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