Thread: Big storm and no power in SA

I was actually (sloppily) including both capacitance and inductance losses together. I have not analysed the situation to see which is the principal factor, but I suspect both are involved.

A long distance point to point HVDC transmission scheme generally has lower overall investment cost and lower losses than an equivalent AC transmission scheme. HVDC conversion equipment at the terminal stations is costly, but the total DC transmission line costs over long distances are lower than AC line of the same distance. HVDC requires less conductor per unit distance than an AC line, as there is no need to support three phases and there is no skin effect.


Depending on voltage level and construction details, HVDC transmission losses are quoted as about 3.5% per 1,000 km, which are 30 – 40% less than with AC lines, at the same voltage levels. This is because direct current transfers only active power and thus causes lower losses than alternating current, which transfers both active and reactive power.

Originally Posted by JDNSW

I was actually (sloppily) including both capacitance and inductance losses together. I have not analysed the situation to see which is the principal factor, but I suspect both are involved.

Yes, there are both capacitive and inductive losses in a three phase transmission system.

If I'm understanding you correctly Eevo, we should be using dc power.

If I remember correctly , Nicola Tesla , shot the whole DC generating and power transmission plans to pieces in favour of AC. He made some real enemies out of it and send some investors bankrupt.

Originally Posted by ramblingboy42

If I'm understanding you correctly Eevo, we should be using dc power.

If I remember correctly , Nicola Tesla , shot the whole DC generating and power transmission plans to pieces in favour of AC. He made some real enemies out of it and send some investors bankrupt.

And how are you going to achieve that? Mechanically and economically? Where are you going to get the amount of copper required?
Or, are you going to use superconductors? How are you going to supply the energy for the refrigeration required? I doubt we have enough coal reserves to do that.

I suggest you read up on "skin effect" an "bundling" in relation to AC transmission networks.

HVDC vs. HVAC transmission | electricaleasy.com

All I can say is, it's 39 here today, so I hope whatever system we have keeps working. Rain would also be nice.

Originally Posted by ramblingboy42

If I'm understanding you correctly Eevo, we should be using dc power.

only for long range transportation.