EMF

[openspaceman]

20 minutes ago, Steven P said:

 

Not sure if they are dong another link but the Norway - UK link lands at Blyth - allows the UK to buy spare hydroelectricity from Norway... and in reverse we could sell them spare wind power to top up their hydro reserves.

 

 

 

Efficiency: At higher voltages you need less current (amps) to send the same power down the line. It is the current that causes most power losses - such as heating the wires - so if you can reduce the current it is more efficient. We can't go high voltage in the house else Mrs Miggins would blow her head off doing the toast in the morning, most of the power supplies in or around towns are no where near the 400kV in the question (You'd know if they were, the substations for that is quite large). 40KV will generally be well away from the population - soiling the view perhaps going over the endless plantations of spruce.

The under sea ones are all HVDC because the capacitance of the water would increase losses for AC. The buzzing from HVAC is worse in wet weather and represents transmission losses. I think AC is cheaper  overland up to1000km but because of planning concerns there will be undersea cables to avoid some overland connections from the north.

[GarethM]

6 minutes ago, openspaceman said:

The under sea ones are all HVDC because the capacitance of the water would increase losses for AC. The buzzing from HVAC is worse in wet weather and represents transmission losses. I think AC is cheaper  overland up to1000km but because of planning concerns there will be undersea cables to avoid some overland connections from the north.

I'm not sure about the AC in water thing, as the cables are that well isolated. But marine life such as sharks etc might be more liable to attack it.

 

One assumes DC effectively cancels itself out, plus also allows better isolation as UK voltage and frequency is different to the continent.

 

Tom Scott did a video about it ages ago, as the EU network is so large it varies, causing clocks to run at a different operating frequency.

[Steven P]

The capacitance in a cable is within it - between the phases rather than it's surrounds, sea water won't affect it much. The way a cable is made up will - a larger subsea cables and so on. HV DC cables are electrically more efficient however each end of the cable - the conversion AC to DC and back again is trickier. For a long distance cable the conversion is acceptable to lower the losses and running costs. Within Europe, including Norway here, we all should have compatible electrical systems and interconnections (domestic, my fridge and TV will work just well on Belgian electricity, 230V AC, 50Hz)

 

AC cables are cheaper to install to get the same power transmitted - been a few years since that college course, but think it was something like DC and 2 phase AC needs 3 cables (phase, phase or neutral and earth), 3 phase AC needs 3 cables (3x phases). 3 phase has 1/3 more power through the copper. We can build smaller transmission towers. For long distances though I think the worry is power losses and to get enough power at the far end to make it worthwhile and not eaten up along the route in losses.

[GarethM]

Oh it's compatible, but UK power has always been a bit spicier than the EU. 

 

Generally it's 220/380 with very little change in the EU, here it's 240/415 and even then it can be 250 depending on the time of day

[Steven P]

20 minutes ago, GarethM said:

Oh it's compatible, but UK power has always been a bit spicier than the EU. 

 

Generally it's 220/380 with very little change in the EU, here it's 240/415 and even then it can be 250 depending on the time of day

 

Can I be all anal, I usually am... officially 230V +10% or -6%.. (same for 3 phase domestic) - which let the UK just keep going at 240V... but officially it is 230... (I think my house generally goes at 244V and new LED bulbs every 6 months). Appliances have to accept the range 215V - 250V, something like that

[Johnsond]

2 hours ago, Steven P said:

 

Not sure if they are dong another link but the Norway - UK link lands at Blyth - allows the UK to buy spare hydroelectricity from Norway... and in reverse we could sell them spare wind power to top up their hydro reserves.

 

 

 

Efficiency: At higher voltages you need less current (amps) to send the same power down the line. It is the current that causes most power losses - such as heating the wires - so if you can reduce the current it is more efficient. We can't go high voltage in the house else Mrs Miggins would blow her head off doing the toast in the morning, most of the power supplies in or around towns are no where near the 400kV in the question (You'd know if they were, the substations for that is quite large). 40KV will generally be well away from the population - soiling the view perhaps going over the endless plantations of spruce.

You might want to have a look at the size of what they are building in the North east in regards the  sub stations and the routes before you pass it off as going over endless spruce plantations. Educate yourself on this one. 

[Steven P]

Pretty sure 2 power lines and a substation arn't gong to ruin the aesthetics of Blyth

[Johnsond]

7 hours ago, Steven P said:

Pretty sure 2 power lines and a substation arn't gong to ruin the aesthetics of Blyth

Educate yourself as I advised. 

I live in Aberdeenshire the North East of Scotland, the links I put up reference SSEs activities in “ The North East of Scotland “ look up “ New  Deer” sub station. 

Regarding the Blyth comment, that town after a long hard period of neglect t is on the  up big time which is nothing but a good thing, as for aesthetics there is a lot more that can and should be done From Lynemouth heading south down the coast to improve things but removing the scars of the areas industrial past ain’t a simple fix. 

[Steven P]

ok

[openspaceman]

10 hours ago, Steven P said:

The capacitance in a cable is within it - between the phases rather than it's surrounds, sea water won't affect it much

 

 

"Long undersea or underground high-voltage cables have a high electrical capacitance compared with overhead transmission lines since the live conductors within the cable are surrounded by a relatively thin layer of insulation (the dielectric), and a metal sheath. The geometry is that of a long coaxial capacitor. The total capacitance increases with the length of the cable. This capacitance is in a parallel circuit with the load. Where alternating current is used for cable transmission, additional current must flow in the cable to charge this cable capacitance. This extra current flow causes added energy loss via dissipation of heat in the conductors of the cable, raising its temperature. Additional energy losses also occur as a result of dielectric losses in the cable insulation. For a sufficiently long AC cable, the entire current-carrying ability of the conductor would be needed to supply the charging current alone. This cable capacitance issue limits the length and power-carrying ability of AC power cables" Donald G. Fink, H. Wayne Beatty, Standard Handbook for Electrical Engineers 11th Edition, McGraw Hill, 1978, ISBN 0-07-020974-X, pages 15-57 and 15-58 via wikipedia