Diesel Car Ban

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bobins
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Re: Diesel Car Ban

Post by bobins »

Mandrake wrote:
25 Aug 2017, 14:54

I hear that the National Grid couldn't possibly cope with electric cars, if everyone plugged in at 6pm it'd just go into meltdown
Yeah but that's what happens when you read rags like the daily mail or the sun. :lol: The whole factually incorrect scaremongering stories doing the rounds saying "don't use your kettle while you charge your car" have been well and truly debunked, it's just absolute nonsense and is based on out of context quotes cherry picked by ignorant journalists from a national grid article. Guess what, I use my 3.6kW kettle while my EV charges - no problems... in fact I use the 10kW electric shower too, or the oven... ;)




That's not strictly true in all circumstances though. There are surveyed and documented towns / streets / areas where it would be a concern if everyone opted to turn on their 'medium powered' car chargers at once. I think the figure given at the time was that these streets / areas only had 1 - 2kW of headroom per household before the local area feed and/or transformer became overwhelmed. In some areas there needs to be work on the local infrastructure [1] before everyone can charge their cars at whatever rate they want wnenever they want without having to think about it.
The sources for this are back in a Govt report I linked to back in a previous discussion about EVs and local electricity infrastructure.

1 - assuming there is a high take up of EVs in that area.

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bobins
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Re: Diesel Car Ban

Post by bobins »

EDC5 wrote:
25 Aug 2017, 16:11
A house may have a 100A breaker... but if more than a few people on the same circuit (street) try pulling 100A the lights will soon go out.....


You only have to look at the numerous videos of exploding pavements in London to see what happens when you stretch the local supply infrastructure that little bit too far :shock:

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Re: Diesel Car Ban

Post by EDC5 »

^^Indeed!

Personally as long as electric cars are recharged during the normal UK power demand 'trough' overnight I can see only advantages. We could rely more on nuclear as the demand would be more constant and not have to burn so much gas for load following CCGT's.

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Re: Diesel Car Ban

Post by Mandrake »

elma wrote:
25 Aug 2017, 15:50
Mandrake wrote:
25 Aug 2017, 15:42
An 11kW (or 22kW) EV charger needs a 3 phase supply - which almost no residential UK property even has. .

That isn't strictly true.
For example if you look at a terrace of houses usually the first one (relative to the electric supply) has 3 phase coming to a box. From the box each single phase will supply 1/3 of the terrace.
There might be 3 phases going to the terrace as a whole, but within each house there will only be one phase going to the meter and consumer unit of that house. So you only have one phase at your disposal to connect an EV charger to, so it doesn't really change my point - the vast majority of residential UK properties will only ever get single phase EV chargers which are limited to 7.2kW, but that's OK as its more than enough.

A 7.2kW charger can add up to 30 miles of range per hour of charging - 10 hours of charging would completely charge a battery that could do 300 miles. So unless you're doing 300+ miles per day in a car with a 100kWh battery, not an issue! Of course if you only did say 60 miles a day, it would only take 2 hours of charging to top up, which could easily be done after midnight on a timer. Going above 7.2kW doesn't really offer much benefit - I'd argue that its better to spread out a lower load over more hours than have everyone trying to charge really rapidly at the same time when they get home.
Older large houses often have 3 phase as well but only one is brought to the meter. It's very cheap and easy to comission the other 2.

This isn't always the case but with EVs looming it may well become a factor in valuing a house soon. It's also possible to use capacitors to convert 1ph to 3ph, having not investigated I'm not sure if this offers reduced amps/watts but I expect so.
That's interesting, but I don't think 3 phase charging at home is necessary unless you were a real road warrior, see my calculation above.
Of course the media have taken that horribly out of context. Each phase would have its own fuse so they are implying that domestic properties have 3ph with 20-30amps available per phase. I might look at ev charger installer certification actually. Could be a good certificate to have.

There's probably good money in it while the grants last - if you are OLEV certified the UK government will pay you, the installer, up to £500 directly towards the installation cost, also in Scotland there is an additional grant of up to £500 on top of that which the Energy Savings trust will pay the owner who is getting the installation done. (in the form of a re-reimbursement)

It looks like most installers pad the cost up to take full advantage of the grants... :wink: [-X

For example the installer I originally looked at who can only do the OLEV part was going to charge me about £200 for the installation, (so they get £700) but I found one in Scotland who can also apply for the EST grant, and they padded the non-OLEV part of the quote up to £499 for pretty much the same charger unit. :rofl2:

So I pay £499 up front but get it all back a few weeks later instead of paying £200 for the same thing and not getting anything back. Craziness.... :roll:

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Re: Diesel Car Ban

Post by Mandrake »

bobins wrote:
25 Aug 2017, 16:20
Mandrake wrote:
25 Aug 2017, 14:54

I hear that the National Grid couldn't possibly cope with electric cars, if everyone plugged in at 6pm it'd just go into meltdown
Yeah but that's what happens when you read rags like the daily mail or the sun. :lol: The whole factually incorrect scaremongering stories doing the rounds saying "don't use your kettle while you charge your car" have been well and truly debunked, it's just absolute nonsense and is based on out of context quotes cherry picked by ignorant journalists from a national grid article. Guess what, I use my 3.6kW kettle while my EV charges - no problems... in fact I use the 10kW electric shower too, or the oven... ;)




That's not strictly true in all circumstances though. There are surveyed and documented towns / streets / areas where it would be a concern if everyone opted to turn on their 'medium powered' car chargers at once. I think the figure given at the time was that these streets / areas only had 1 - 2kW of headroom per household before the local area feed and/or transformer became overwhelmed. In some areas there needs to be work on the local infrastructure [1] before everyone can charge their cars at whatever rate they want wnenever they want without having to think about it.
The sources for this are back in a Govt report I linked to back in a previous discussion about EVs and local electricity infrastructure.

1 - assuming there is a high take up of EVs in that area.

This is not what the misleading articles were discussing, they were making the claim that if you tried to charge your EV and use your kettle at once it would blow YOUR fuse (circuit breaker these days) in your own house. Which is complete garbage, unless the installer didn't do their due diligence and installed a 32 amp charger in a house with a 60/80A fuse and too many other heavy loads.

The installer that quoted mine was careful to inspect the DNO fuse, meter and consumer unit before quoting for the install. (As it turns out I need a smaller secondary consumer unit adding as all the ways in my existing one are full, but I have plenty of reserve capacity on the main fuse for a 32 amp charger)

What you're talking about with a lack of capacity in an overall street is certainly an issue to be dealt with in some areas. This is why I don't think home chargers should be too high powered - we really don't want to be going over 7.2kW, which is a good balance between charging time and not overwhelming the local electrical supply.

11kW or higher home charging is strictly for those with large 3 phases supplies, which is not most of us, and unless you're a real road warrior, not necessary even if you have access to 3 phase.

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Re: Diesel Car Ban

Post by bobins »

Mandrake wrote:
25 Aug 2017, 16:47

This is not what the misleading articles were discussing, they were making the claim that if you tried to charge your EV and use your kettle at once it would blow YOUR fuse


Ah, I see !

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Re: Diesel Car Ban

Post by myglaren »

The town I used to live in in Sweden - Borås - as well as having a town-wide central heating system run on mainly domestic waste also has a biomethane program that fuels the local buses.

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Re: Diesel Car Ban

Post by CitroJim »

myglaren wrote:
25 Aug 2017, 17:07
The town I used to live in in Sweden - Borås - as well as having a town-wide central heating system run on mainly domestic waste also has a biomethane program that fuels the local buses.



That's seriously good :)

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Re: Diesel Car Ban

Post by white exec »

Interestingly, most medium-large houses built here in the last 20 years have a 3ph supply, usually 40A per phase available. Customers contract for a chosen maximum kW of supply: the lower the figure, the lower the monthly standing charge. New smart meters make sure the agreed figure is not exceeded. If you want more power, you 'up your potencia' to a higher peak figure, and the meter is remotely reprogrammed accordingly.

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Re: Diesel Car Ban

Post by Mandrake »

white exec wrote:
25 Aug 2017, 21:13
Interestingly, most medium-large houses built here in the last 20 years have a 3ph supply, usually 40A per phase available. Customers contract for a chosen maximum kW of supply: the lower the figure, the lower the monthly standing charge. New smart meters make sure the agreed figure is not exceeded. If you want more power, you 'up your potencia' to a higher peak figure, and the meter is remotely reprogrammed accordingly.

Yes, in many countries in Europe 3 phase in normal residential houses is common place, particularly in Germany.

In these countries 11kW and 22kW EV home chargers are available and are often used. 11kW being 16 amps per phase and 22kW being 32 amps per phase. I suspect Germany gets a lot more than the 40A per phase that you're saying Spain does, as 40A/phase for the whole house is a bit marginal for even a charger that is 16A per phase and infeasible for 32A.

The problem with a 3 phase 11kW charge point is that each phase is only 3.6kW, so although a single phase car can still charge from such a point, it can only utilise one phase - eg 3.6kW.

All cars with the older style Type 1 connector - which includes my Ion and the Nissan Leaf, are only single phase as the Type 1 connector only has enough pins for single phase. For three phase charging the Type 2 connector (with two extra pins) is required, which is the standard connector in the UK and most of Europe, but not all cars that have this connector support 3 phase charging either. So if you plug a car that can charge at 7.2kW using single phase into an 11kW charger you'll actually only charge at 3.6kW...

Because the current per phase on a 3 phase system would typically be less than the current available on a single phase system like the UK you'll typically find EU cars designed for 3 phase charging and those designed for the UK typically designed for single phase charging, and mixing and matching the two systems will result in less than optimal speed, although there is enough compatibility that you will always be able to charge.

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Re: Diesel Car Ban

Post by elma »

Mandrake wrote:
25 Aug 2017, 16:43
There might be 3 phases going to the terrace as a whole, but within each house there will only be one phase going to the meter and consumer unit of that house. So you only have one phase at your disposal to connect an EV charger to, so it doesn't really change my point - the vast majority of residential UK properties will only ever get single phase EV chargers which are limited to 7.2kW, but that's OK as its more than enough.

Absolutely agree but the point was that I can install 3ph to most residences for under £200 in parts.
It's not a major rejig of existing infrastructure to have 3ph in most cases.
Maybe I should have just said that :)
If we get to the stage where we all drive electric many households, especially flats, will have 3+ cars to charge and 3ph will become increasingly necessary.
Well that or people taking responsibility for their own power, wind turbine anyone?

I am quite interested in the EV installer stuff.
I will have a look next week and see if theres a course worth doing.
I fancy going back to college in September, not made any academic progress for some time now.

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Re: Diesel Car Ban

Post by EDC5 »

How does a three phase household handle a 240v single phase load? is there a big neutral wire supplied to the property 3 times the thickness of the three phases in case you want to run 3 separate 100A loads?

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Re: Diesel Car Ban

Post by Mandrake »

EDC5 wrote:
25 Aug 2017, 22:28
How does a three phase household handle a 240v single phase load? is there a big neutral wire supplied to the property 3 times the thickness of the three phases in case you want to run 3 separate 100A loads?

A house with 3 phase supply may use the 3 phases directly for large appliances like an HVAC system, but normal 240v 3 pin sockets would run from a single phase each, with some sockets in the house coming from each phase in an attempt to roughly balance the current on each phase.

The neutral wire doesn't need to be 3x the thickness of the phase wires - one of the reasons for using a 3 phase system for distribution in the first place is that in the worst case (only current being drawn from one phase) the neutral current is only equal to the current of one phase wire.

As soon as you start drawing current from the other two phases the better the balance of current between the three phases the less neutral current there is, and in perfect balance there is no neutral current.

Trying to balance the three phases within a single house with a random distribution of appliances and various sockets connected to different phases around the house would be nearly impossible though.

In the UK where most houses are single phase the 3 phase supply from the street transformer is arranged so that different houses in the street run from different phases and they are grouped into three phase groups in an effort to balance the demand of the three phases among the houses on the street - which is much more feasible than trying to balance the use within a single house, as usage of whole houses (especially if you have multiple houses per phase) is much more likely to even out than usage of different rooms in the same house.

So I think in general single phase at a higher current is a better way to supply a typical small to medium house. 3 phase really only makes sense for much larger houses or commercial buildings.
Last edited by Mandrake on 25 Aug 2017, 22:59, edited 1 time in total.

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Re: Diesel Car Ban

Post by elma »

Simons answer sums it up well but I'd typed mine as he posted his so you can have a second version from me as well.

Sort of.
Not all 3ph equipment uses a neutral, in fact most doesn't.
A 1ph load would just be wired into a single phase and neutral.
A big 3ph consumer unit (like in a hotel) would stagger the phases and use a shared neutral, i.e. circuits 1,4,7 on ph1 circuits 2,5,8 on ph2 circuits 3,6,9 on ph3 etc.
Because the phases are 120 degrees out of phase the shared neutral isn't actually triple thickness, in fact it's often smaller than the phase conductors.
This is because the current is shared across the phase conductors and the neutral itself actually carries a minimal current due to the phase difference essentially cancelling out the current. (think transverse wave superposition)
The Earth on the other hand is usually noticeably thicker as the potential fault current is rather high.

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Re: Diesel Car Ban

Post by EDC5 »

Ah I see, so because of the 120 degree shift of the phases they can all share the same neutral as they're not using it at the same time? is that right?