The Western HVDC Link

I bet that Pole 1 refers to the conductor of the opposite polarity...


Can you get Drummond Test Lamps with an internal diode to find out which is which?  ?

Clive

What would be the current of a 400Kv grid circuit? I'm guessing about 4000 amps per phase is this a sensible guess? Also I've noticed the pylons round here have 3 conductors per phase

It is 400kV line to line remember, not line to neutral (which is not distributed)  so 3 lines carrying 1kA each is  more like 3* 230kV * 1000A  is 690 MVA per kilo-amp.


A  GVA or few is indeed the upper practical  limit, both for dissipation, and robustness against faults - more and it becomes worth a second line. It is also a similar level to the practical upper limit for a power station.

Thanks mapj1 for the information when you look into distribution and grid level power and voltage it all gets into very big numbers all very impressive stuff. I looked at the cable catalogue mentioned further up the page I like the names they used for there products thought they were tree mendouse

Overhead lines at 400kV will use bundled conductors, not single conductors - that is, for each phase 3 or 4 conductors held in a spaced bundle.  The spacing is both to improve cooling and also to increase the effective diameter of the conductor bundle to reduce corona discharge.  In addition the spacers, which are flexible, help to damp vibrations.

In the UK 400kV lines are most commonly either 3 x 400 mm2 ACSR (Zebra) or 4 x 400 mm2 ACSR (Zebra), the 3 bundle rated about 1200MVA and the 4 bundle rated about 1800MVA.  [ACSR = aluminium conductor steel reinforced, that is aluminium strands laid around a stranded steel core for tensile strength]

Thanks John Russell  the grid lines near hear are 3 per phase on one side and four per phase in the other direction one line goes west the other east not sure which is which. Also what's the significance of zebra? Thanks regards Kelly

The west line goes thru Devon and in to Cornwall then it loops round to north Devon then into Wales the east one goes to Southampton then eventually onto dunganess  I don't know which way power flows.

the grid lines near hear are 3 per phase on one side and four per phase in the other

Not sure if it's a similar situation as a line of pylons near me. A couple of years ago it all six conductors had a bundle of 4 cables each - then the summer before last they "rewired" one side and it ended up with bundles of 3 instead of the original 4 - then last summer the rewired the other side so that has bundles of 3 now as well. So for a year they looked a bit odd.

   - Andy.