Quite an interesting article in E&T:
How a lack of joined-up thinking could block EV charging expansion | E&T Magazine (theiet.org)
I thought that UK substation fuses were more that 200 - 300A (800A??).
Is the unbalanced phase problem realistic?
Does the 'car to grid' feeding in to the cable and potentially causing an unmonitored overload also apply with other local generation such as solar PV?
Interesting - a lot of goods points there.
Do many DNO cables really have a reduced N? I thought that in modern concentric cables the copper 'armour' would have pretty much the same resistance as one of the line cores - it might have a smaller c.s.a. in some cases but that just balances out the increased resistance of the aluminium cores. All the old PILC cables I've seen looked to have a same-sized core for N, and the sheath/armour originally for PE only - even when converted to PME the original N core is retained in parallel. Were there lots of CONSAC cables with smaller Ns?
The phase imbalance issue/knowing which phase a customer is on ... I wonder if there might be some natural compensation where multicore/ABC cables are used - i.e. if one core is nominally overloaded but other cores are running cool, then heat from the overloaded core would find it easier to escape than if all the other cores were at a similar temperature, so overall temperatures might be still acceptable. e.g. a 185mm2 SWA might be rated at 243A 3-phase, but that goes up to 292A for a similar cable with only 2 loaded cores - so there may be some margins there.
In some ways the EV issue isn't entirely new - we've had areas with lots of electric storage heating for instance - and seem to have managed in the past without a 'booking system'. Overall there will be a considerable amount of natural diversity - not everyone will need to fully charge theor car every night, just like not everyone fills up with petrol every day. On average EVs will need charging less often or for far shorter durations. The actual numbers are still a bit of an unknown though, so certainly still worth keeping in mind until the evidence becomes available.
- Andy.
Interesting - a lot of goods points there.
Do many DNO cables really have a reduced N? I thought that in modern concentric cables the copper 'armour' would have pretty much the same resistance as one of the line cores - it might have a smaller c.s.a. in some cases but that just balances out the increased resistance of the aluminium cores. All the old PILC cables I've seen looked to have a same-sized core for N, and the sheath/armour originally for PE only - even when converted to PME the original N core is retained in parallel. Were there lots of CONSAC cables with smaller Ns?
The phase imbalance issue/knowing which phase a customer is on ... I wonder if there might be some natural compensation where multicore/ABC cables are used - i.e. if one core is nominally overloaded but other cores are running cool, then heat from the overloaded core would find it easier to escape than if all the other cores were at a similar temperature, so overall temperatures might be still acceptable. e.g. a 185mm2 SWA might be rated at 243A 3-phase, but that goes up to 292A for a similar cable with only 2 loaded cores - so there may be some margins there.
In some ways the EV issue isn't entirely new - we've had areas with lots of electric storage heating for instance - and seem to have managed in the past without a 'booking system'. Overall there will be a considerable amount of natural diversity - not everyone will need to fully charge theor car every night, just like not everyone fills up with petrol every day. On average EVs will need charging less often or for far shorter durations. The actual numbers are still a bit of an unknown though, so certainly still worth keeping in mind until the evidence becomes available.
- Andy.
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