Originally posted by SwissGambit
Wire loss or line loss is through heat. Line loss occurs because of the voltage divider effect. The formula for the voltage drop across the wire is
Vloss = Rwire/(Rwire + Rload) * Vsupplywhere R is resistance. The power loss from the wire is
P = Vloss*Vloss/Rwire
Superconductor means R in the 'wire' is very close to 0 - so Vloss will also tend to go to 0 and thus very little power is lost/heat dissipated.
Not quite. It does lose through heat but if you have a long transmission line running 50 or 60 hertz, that means it is an antenna and a good fraction of it is actually transmitted as 50 or 60 Hz radio waves. That is a radio wave with a wavelength of over 3000 miles, close to 5000 Km. If you have a wire length of 1500 miles, that represents close to 1/2 wavelength and if precautions are not taken ( you can engineer out most of that radiation) you would lose a lot more than the 10% now lost in long distance lines. If you wanted to radiate that energy you could transmit more than 90% of it as radio waves. Fortunately you can prevent most of that loss by having two lines close together, one the + and the other the - (AC but one will be the opposite polarity), then it becomes a transmission line and not a whole lot is lost but some still leaks out.
Some energy is also lost to corona discharges off dirty insulators which, at 1 million volts for the big guys, is quite a problem. Corona discharge is where the electrons spit themselves right off a conductor if the voltage is high enough and the radius of curvature of the conductor is small enough which in this case could be a damp piece of dirt sticking out of a high voltage insulator where the voltage gradient builds up higher than the insulator can hold back, huge local electric fields literally accelerate electrons right into the sky.
When that happens and you are nearby with an old AM radio you can hear it hissing and buzzing for miles around. They fix that when the find it by taking a helicopter and spraying the insulator with some cleaning liquid. A very dangerous job as you can imagine. The pilot is flying the thing very close to the lines and a long nozzle dangles out of the chopper and sprays the insulator to clean it.
Not a job I would lust after.....