Installing a 3 phase rapid EV charger?

[HappyHippyDad]

Im finding all those swirling conductors quite pleasing to the eye.

I thought you might Westward
It is rather nice isn't it.

 

[HappyHippyDad]

Yes the upstream device will need to be at a minimum Type A (assuming DC Leakage protection in the EVSE), otherwise Type B. Obviously also S-type (time delayed).

For example a number of EVSEs I installed for a well-known courier firm I replaced the upstream S-type RCCB for a Type A 300mA for the distribution circuit. This went to a switch fuse and then onto the DBs. I had triple pole circuit breakers in the DBs feeding four pole RCCBs. (It was a TT installation.)

Is there a reason why I shouldn't just bypass the 300mA RCD by using the Henley blocks upstream?
Meter tails into a separate enclosure housing all the bits I need.

 

[Risteard]

Just to add that obviously regardless of Earthing arrangements the RCDs must break all live conductors (just in case my earlier post is misconstrued).

 

[pc1966]

Something worth considering with three-phase charge points is that the phase sequence should actually be varied between units. So if there is a charge point connected L1-L2-L3 then an additional unit should be L2-L3-L1 or L3-L1-L2. This is to prevent them all pulling off the same phase where the vehicle is only capable of single phase charging. Obviously maintain the phase rotation though.

I had always assumed that EV chargers are like old 12V charger or many 3-phase UPS where they would use all phases to generate the DC for charging, but I guess they supply AC to the EV for that?

A very good point to spread the load over the phases!

 

[pc1966]

Is there a reason why I shouldn't just bypass the 300mA RCD by using the Henley blocks upstream?
Meter tails into a separate enclosure housing all the bits I need.

That would appear a better option if you can get a suitable RCBO or similar.

It might be the Matt:e with RCBO is suitable, but check what it needs up-stream. At the very least it would need an isolator, but you might be better with a 3PN switched-fuse with something like 40A-50A fuses to give total selectivity with 80-100A incomer fuses.

I see there is an isolator at the incomer which is great, but I would rather not have to totally shut down such a large installation just for any future EV problems being fixed.

 

[HappyHippyDad]

That would appear a better option if you can get a suitable RCBO or similar.

It might be the Matt:e with RCBO is suitable, but check what it needs up-stream. At the very least it would need an isolator, but you might be better with a 3PN switched-fuse with something like 40A-50A fuses to give total selectivity with 80-100A incomer fuses.

I see there is an isolator at the incomer which is great, but I would rather not have to totally shut down such a large installation just for any future EV problems being fixed.

Could you tell me why the Matt:e would need a separate isolator? It has a 5 pole mains isolator which could be used to isolate from the other electrics if a fault occurred.

 

[HappyHippyDad]

Given the cost of the matt:e and it being a farm could you not get a rod in using some machinery?
Like wise if its being used solely inside then use the pme.

Actually I don't think a rod will be possible. The charger will be housed in the meter room. The meter room has PME earthing terminals in it which will be simultaneously accessible with the charger (or tractor when it is being charged). Looks like it has to be Matt:e! Hopefully the charger has a PEN fault device already!

 

[Julie.]

...
Or, I could take the supply from the henley blocks to the left of the 300mA RCD which have no RCD protection? This seems better, as the cable from the Henly blocks to sub DB will not need RCD protection and I could locate it close to the henley blocks in the same room.

Yes, take tails from the Henry blocks into a kmf, swa to the charge point (assuming the charge point has integral rcd protection etc)
If the charge point doesn't have integrated protection, then instead of a kmf, use an rcbo, rcd/mcb, or rcd/fuse combination.

(Assuming supply is tncs or tns)

if TT then in both cases you would need a delayed rcd after the tails.

 

[westward10]

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[HappyHippyDad]

Yes, take tails from the Henry blocks into a kmf, swa to the charge point (assuming the charge point has integral rcd protection etc)
If the charge point doesn't have integrated protection, then instead of a kmf, use an rcbo, rcd/mcb, or rcd/fuse combination.

(Assuming supply is tncs or tns)

if TT then in both cases you would need a delayed rcd after the tails.

All sounds good, thanks Julie.
I shall hopefully read the spec of the charger on Monday.
As above, I don't think TT is an option as it will be simultaneously accessible to PME.

 

[Julie.]

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Arrrhhhh

I most certainly wrote Henley, fudging autokorrect!

Edit, yup it "corrected" me again!!!

 

[Risteard]

Is there a reason why I shouldn't just bypass the 300mA RCD by using the Henley blocks upstream?
Meter tails into a separate enclosure housing all the bits I need.

You can call me old fashioned but I prefer to maintain an S-type upstream for at least some redundancy and fault protection for the cables feeding the DB.

 

[partplonker]

I had always assumed that EV chargers are like old 12V charger or many 3-phase UPS where they would use all phases to generate the DC for charging, but I guess they supply AC to the EV for that?

Yes, they supply AC straight to the EV for it to do the DC conversion. It's also worth mentioning that 95% of electric vehicles cannot handle more than 11kW AC or 16A per phase. There are very few EVs that can actually make use of the full 22kW.

 

[HappyHippyDad]

You can call me old fashioned but I prefer to maintain an S-type upstream for at least some redundancy and fault protection for the cables feeding the DB.

But wouldn't they already have fault protection given that its ADS with a good Ze (0.15ohms)?
I would completely agree if it was TT, it would then be a necessity.
Are you just saying it's a good idea to have as well as ADS?

 

[Risteard]

But wouldn't they already have fault protection given that its ADS with a good Ze (0.15ohms)?
I would completely agree if it was TT, it would then be a necessity.
Are you just saying it's a good idea to have as well as ADS?

Yes sorry I was referring to where a TT system exists. It wasn't intended to suggest that I consider it necessary for TN systems.
Apologies for the confusion.

 

[Julie.]

I had always assumed that EV chargers are like old 12V charger or many 3-phase UPS where they would use all phases to generate the DC for charging, but I guess they supply AC to the EV for that?

A very good point to spread the load over the phases!

EV chargers do use all three phases, convert to dc and pass this to the vehicle.

However, I think the op is installing an EV Charge Point (EVCP) which merely connects either single phase 230V or three phase 400V to the vehicle, in which case the charger is within the vehicle.

When connected to an EVCP the charge rate is limited by the lower of the EVCP (32A, 16A, 10A ) or the rating of the charger within the vehicle (might be 9.2kW)

Whereas with an EV charger, you can have very high charge capacity 50kW, 70kW, 150kW etc.

These rapid chargers are pretty big bits of kit though.

 

[pc1966]

Yes sorry I was referring to where a TT system exists. It wasn't intended to suggest that I consider it necessary for TN systems.
Apologies for the confusion.

I think the up-front 300mA RCD here is due to it coming under agricultural areas and for fire risk reduction. Supply seems to be TN-C-S.

But I agree with you that for TT systems I would always prefer a delay RCD as incomer and then RCBOs afterwards, as no *single point of failure that could leave the CPC live.

[*] Single here as in fault in a RCD not spotted by **anyone doing a periodic test, clearly it needs two fault: some L-CPC fault and then the RCBO/30mA RCD not working.

[**] AKA friends of the seal faery.

 

[pc1966]

Could you tell me why the Matt:e would need a separate isolator? It has a 5 pole mains isolator which could be used to isolate from the other electrics if a fault occurred.

If it is easy to isolate internally then you would not. It kind of depends on the trouble caused to isolate the whole system to work on the Henley blocks and feed to Matt:e versus the cost/space needed for some form of isolation.

It also depends on what the Matt:e requires in the way of any input protection / max supply PSCC. If it is fine with 100A fuses, etc, for example if has a MCB/RCBO as the only incoming connection and that can break 6kA, then not needed.

 

[HappyHippyDad]

If it is easy to isolate internally then you would not. It kind of depends on the trouble caused to isolate the whole system to work on the Henley blocks and feed to Matt:e versus the cost/space needed for some form of isolation.

It also depends on what the Matt:e requires in the way of any input protection / max supply PSCC. If it is fine with 100A fuses, etc, for example if has a MCB/RCBO as the only incoming connection and that can break 6kA, then not needed.

So it's looking like this charger just requires a 5 pin 16A commando socket and that this scenario isn't part of section 722 as its just ELV on the vehicle.

I was hoping to run past you (and others, just happened to quote you) my final (hopefully) thoughts as this is my first delve into 3 phase.

Change the 3 pole mcb in the 3 phase board for a C20. Take from this to a separate small CU housing a 4 pole Type AC RCD. From there I go to the commando socket (or possibly bypass the CU and just have the required RCD combined in the commando socket)? Probably all in 5 core 2.5mm H07RN?

I have chosen a Type AC RCD for poor reasons. There is an upstream 300ma RCD which I was trying to avoid changing to a Type A. Also, type AC RCD's are 'usually' acceptable (i.e meet the regulations) to use to protect sockets.

I am unsure how to ascertain if a type A is required as I cant get anybody at Avant who understands what DC leakage is and how likely it is with the charger/loader.

Main question is the highlighted bit though.

 

[partplonker]

So it's looking like this charger just requires a 5 pin 16A commando socket and that this scenario isn't part of section 722 as its just ELV on the vehicle.

I was hoping to run past you (and others, just happened to quote you) my final (hopefully) thoughts as this is my first delve into 3 phase.

Change the 3 pole mcb in the 3 phase board for a C20. Take from this to a separate small CU housing a 4 pole Type AC RCD. From there I go to the commando socket (or possibly bypass the CU and just have the required RCD combined in the commando socket)? Probably all in 5 core 2.5mm H07RN?

I have chosen a Type AC RCD for poor reasons. There is an upstream 300ma RCD which I was trying to avoid changing to a Type A. Also, type AC RCD's are 'usually' acceptable (i.e meet the regulations) to use to protect sockets.

I am unsure how to ascertain if a type A is required as I cant get anybody at Avant who understands what DC leakage is and how likely it is with the charger/loader.

Main question is the highlighted bit though.

If 722 doesn't apply, then my understanding is that a 30mA type AC meets the requirements for a socket < 32A and reg 411.3.3 as you said.

I fitted a 4 pole type A RCD recently (MCG branded from CEF) and there was no difference at all in cost between the type A and type AC. Both were about £50, so might as well fit a type A and you've gone above and beyond.