DIYbanter - View Single Post - Ideal electrical systems (just idle curiosity)

The Natural Philosopher[_2_]

On 27/07/14 21:40, wrote:
Nightjar wrote:
AC for simple long-distance transmission...
Except for underwater cables, where it can cause unacceptable
transmission losses.

How does immersing a 11kV AC cable in water increase transmission
losses? This isn't a joke question, I can't see how the medium
surrounding a cable changes the action of the cable itself, other
than cooling effects.

The conductive medium surrounding it means that unlike a 132kV cable
string 50 meters in the air, there is considerable capacitance to
ground. Only the cable insulation stand between it and ground, and a
conductive - a very conductive - ground.

The pout of phase current isn't loss in itself, but it does mean higher
currents in the wire for the same power output at the far end and higher
currents mean higher resistive losses.

jgh

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