On 16/02/2021 19:18, Paul wrote:
Roger Hayter wrote:
On 16 Feb 2021 at 14:50:21 GMT, "newshound"
wrote:

On 16/02/2021 14:12, Clive Arthur wrote:
Â*On 16/02/2021 13:57, Paul wrote:

Â*Explanation snipped

Â*Thanks for that.

+1

Thirded.Â* But I really cannot stop myself quibbling about reactive
"power",
though I suspect you didn't mean it.


The units of measure are volt-ampere-reactive.

To quote the instructor "reactive power sloshes around in the network,
between the load and the generator". The current flow makes some
of the conductors warmer as a result. It's not consumed as such.

https://energyinnovationproject.com/...eactive-power/


Â*Â* "Reactive power - the delay between voltage and current at a given
point - is
Â*Â*Â* subjected to transmission constraints. As a result, it is often
necessary to
Â*Â*Â* produce reactive power close to the location where it is needed."

To carry reactive power, you still need the wire size for it. That's
the transmission constraint.

Â*Â* Paul

Perhaps another example might be helpful. Most of the UK first
generation civil nuclear reactors (Magnox) had to be down-rated after
the discovery of unexpected corrosion problems. So the generators were
operating at somewhat below their original design conditions. This meant
that the copper windings in the rotor and stator were thicker than they
needed to be. This in turn meant that they could be operated so as to
generate extra "reactive power". Although the volts and amps are a bit
out of phase, the resistive heating in the windings is just related to
the current; thicker windings mean they can carry more current, and
hence export MegaVARs as well as Megawatts, helping to contribute to
grid stability. Under the original pool system I don't think MegaVARs
were actually traded, there was some sort of fudged "Ancilliary
Services" payment. I believe that under NETA MVars are traded similarly
to MW.