Installing a 3 phase rapid EV charger?

HappyHippyDad · Feb 11, 2022

A bit of an embarrassing question.

I have a regular customer who I enjoy working for. He has asked me to install an EV rapid charger for his avant loader (electric tractor type thing). I always turn down 3 phase jobs as I don't feel I understand it fully, but I'd like to do this job.

I believe this is the charger (400V/32A version) Rapid battery charger, e6 - https://www.avanttecno.com/uk/options/rapid-battery-charger-e6

I have added a picture of the 3 phase supply.

1. Are there any additional tests to do, compared with single phase? Phase rotation etc.

2. Is it simply a matter of connecting L1, L2, L3 from the Henly blocks (or perhaps the 3 phase merlin gerlin board) into whatever the instructions say is needed? (eg 30mA RCD)

3. I get a little confused by the role of the neutral in polyphase. Does the neutral have a role in 3 phase or is it simply there to support single phase appliances?

[ElectriciansForums.net] Installing a 3 phase rapid EV charger?

pc1966 · Feb 11, 2022

HappyHippyDad said:
1. Are there any additional tests to do, compared with single phase? Phase rotation etc.

EDIT: First point is your safe isolation test has a lot more checks (10 instead of 3)!

L1 to L2,L3,N,E
L2 to L3,N,E
L3 to N,E
N to E

You should verify phase rotation and that phases are correctly assigned all the way (i.e. L1 at the end is from L1 at the supply). Even though most electronic loads don't really care about rotation direction, it is still wrong to not get it right!

The PSCC is usually taken as twice the highest of the three L-N PSCC (on the assumption N has the same impedance as L when measured, and then under the worst-case L1-L2-L3 "bolted 3-phase fault" the virtual neutral has zero impedance).

HappyHippyDad said:
2. Is it simply a matter of connecting L1, L2, L3 from the Henly blocks (or perhaps the 3 phase merlin gerlin board) into whatever the instructions say is needed? (eg 30mA RCD)

You will almost certainly need the N as well, and some form of OCPD (i.e. fused-switch or MCB/RCD or RCBO)

Taking it from the existing board is fine if there is space and you can get compatible RCBO for it. Ask @westward10 as he seems to know every board ever made!

HappyHippyDad said:
3. I get a little confused by the role of the neutral in polyphase. Does the neutral have a role in 3 phase or is it simply there to support single phase appliances?

For simple loads like a 3-phase motor you may not need N as it runs off the L1-L3 lines alone.

But in most cases it is needed as there will be some loads to N for single-phase work (e.g. electronic controller for main 3-phase motor, etc), and some "3-phase" units are star-connected and not always balanced (e.g. heater with 3 setting that simply select L1, L1/L2, or L1/L2/L3) so without N the voltages are wrong and potentially dangerously so.

Julie. · Feb 11, 2022

As per PC's post, you would definitely need the neutral on the charger as some vehicles can only actually charge on single phase, but they still use the same connector.

All chargers in vehicles tend to need the neutral as they have to be able to use a single phase supply as that might be all that's available.

Specialist vehicles such as fork lifts etc may be different.

Phase rotation won't matter, but should be done right anyhow.

westward10 · Feb 11, 2022

If there are three spare ways in the Merlin board then yes take the circuit from there but you will have to fit a separate rcd as you won't get a four pole rcbo for that board.

HappyHippyDad · Feb 11, 2022

pc1966 said:
EDIT: First point is your safe isolation test has a lot more checks (10 instead of 3)!

L1 to L2,L3,N,E
L2 to L3,N,E
L3 to N,E
N to E

You should verify phase rotation and that phases are correctly assigned all the way (i.e. L1 at the end is from L1 at the supply). Even though most electronic loads don't really care about rotation direction, it is still wrong to not get it right!

The PSCC is usually taken as twice the highest of the three L-N PSCC (on the assumption N has the same impedance as L when measured, and then under the worst-case L1-L2-L3 "bolted 3-phase fault" the virtual neutral has zero impedance).

You will almost certainly need the N as well, and some form of OCPD (i.e. fused-switch or MCB/RCD or RCBO)

Taking it from the existing board is fine if there is space and you can get compatible RCBO for it. Ask @westward10 as he seems to know every board ever made!

For simple loads like a 3-phase motor you may not need N as it runs off the L1-L3 lines alone.

But in most cases it is needed as there will be some loads to N for single-phase work (e.g. electronic controller for main 3-phase motor, etc), and some "3-phase" units are star-connected and not always balanced (e.g. heater with 3 setting that simply select L1, L1/L2, or L1/L2/L3) so without N the voltages are wrong and potentially dangerously so.

Julie. said:
As per PC's post, you would definitely need the neutral on the charger as some vehicles can only actually charge on single phase, but they still use the same connector.

All chargers in vehicles tend to need the neutral as they have to be able to use a single phase supply as that might be all that's available.

Specialist vehicles such as fork lifts etc may be different.

Phase rotation won't matter, but should be done right anyhow.

westward10 said:
If there are three spare ways in the Merlin board then yes take the circuit from there but you will have to fit a separate rcd as you won't get a four pole rcbo for that board.

Very glad the 3 of you posted, thanks!

A further basic question... so I would take the L1, L2, L3 from a 3 pole MCB that is in the CU (and the N from the neutral bar) to the required 4 pole RCD (or whatever the MI say to take it to). (pic of CU attached).

I'm cringing a bit asking that as I know its such a simple thing. Is it simply the same as taking a supply from a single phase CU to feed whatever it is you want to feed (I.e sub DB, item itself etc) but you have 3 lines instead?

pc1966 · Feb 11, 2022

HappyHippyDad said:
A further basic question... so I would take the L1, L2, L3 from a 3 pole MCB that is in the CU (and the N from the neutral bar) to the required 4 pole RCD (or whatever the MI say to take it to).

Yes, just like that!
<insert Tommy Cooper gag>

HappyHippyDad said:
I'm cringing a bit asking that as I know its such a simple thing. Is it simply the same as taking a supply from a single phase CU to feed whatever it is you want to feed (I.e sub DB, item itself etc) but you have 3 lines instead?

Mostly this is the case.

It is always better to ask if you don't know!

pc1966 · Feb 11, 2022

One thing that appears in the picture above is the selection of meters. Will the EV charger need to have its electric usage accounted for separately? If so you might need to put in a billing meter for it that can be used to reconcile usage with the main meter, etc.

HappyHippyDad · Feb 11, 2022

pc1966 said:
One thing that appears in the picture above is the selection of meters. Will the EV charger need to have its electric usage accounted for separately? If so you might need to put in a billing meter for it that can be used to reconcile usage with the main meter, etc.

I don't think it will need it's own meter as this will be the owners tractor, I will ask him though as he has asked for meters before on other work around the place.

A 3 phase meter! More questions!

I've just thought of a bit more in relation to cable size....

Lets say this is the 400V/32A charger.

1. Does each line conductor have to be able to cope with 32A?

2. I realise we have been given 32A in this case, but if we just had the wattage of the charger (lets say 22kW), is the calculation the same as single phase. I.e 22000/400 = 55A?

timhoward · Feb 11, 2022

Be extra careful about old and new colours! Old black and blue have exactly opposite functions to new black and blue. If a new circuit you shouldn’t hit this issue though.
IR tests - basically test every permutation.

You’ll be fine, enjoy it, and want to do more!

Gavin John Hyde · Feb 11, 2022

the actual circuit is standard 3 phase from what i can see, not sure if it needs PEN fault or Type A rcd etc as its not a standard ev charger within the code of practice etc.

pc1966 · Feb 11, 2022

HappyHippyDad said:
I don't think it will need it's own meter as this will be the owners tractor, I will ask him though as he has asked for meters before on other work around the place.

A 3 phase meter! More questions!

If needed then something like this should do and does not need a separate enclosure:

Electricity Billing Meters | CEF

HappyHippyDad said:
I've just thought of a bit more in relation to cable size....

Lets say this is the 400V/32A charger.

1. Does each line conductor have to be able to cope with 32A?

Yes, if that is the spec.

Check the cable tables though as the rating for, say, 6mm, is different if single phase or three-phase as more I^2*R losses per bundle.

HappyHippyDad said:
2. I realise we have been given 32A in this case, but if we just had the wattage of the charger (lets say 22kW), is the calculation the same as single phase. I.e 22000/400 = 55A?

No your equivalent is 22000 / (3 * 230) = 32A

If you imagine a star-connected load, then you can see that each L current with the L-N voltage gives you 1/3 of the total power.

The equivalent delta case (400V L-L) is more complicated as each L current is shared by two of the arms (say L1 has loads going to both L2 and L3), and not in-phase to make any calculation simple. Answer is 22000 / (sqrt(3) * 400) and is the "same" (though 400V L-L is not exactly the same as 230V L-N)

TL;DR: So just work with the star model as it gives the same answer!

pc1966 · Feb 11, 2022

Gavin John Hyde said:
the actual circuit is standard 3 phase from what i can see, not sure if it needs PEN fault or Type A rcd etc as its not a standard ev charger within the code of practice etc.

Good point as it looks TN-C-S supply.

Risteard · Feb 11, 2022

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.

HappyHippyDad · Feb 11, 2022

Gavin John Hyde said:
the actual circuit is standard 3 phase from what i can see, not sure if it needs PEN fault or Type A rcd etc as its not a standard ev charger within the code of practice etc.

I'll try and find some specs for the unit, but something like this may be suitable?

3 Phase EV Connection Unit with 4 Pole 32A Type A RCBO

Built-in matt:e O-PEN technology, which allows for the connection of 1 x 32A three phase load to the existing PME earthing facility

www.cef.co.uk

Is this the standard price for a 3 phase Matt e, expensive!

Risteard · Feb 11, 2022

HappyHippyDad said:
I'll try and find some specs for the unit, but something like this may be suitable?

3 Phase EV Connection Unit with 4 Pole 32A Type A RCBO

Built-in matt:e O-PEN technology, which allows for the connection of 1 x 32A three phase load to the existing PME earthing facility

www.cef.co.uk

Is this the standard price for a 3 phase Matt e, expensive!

Yeah - CEF are actually one of the cheaper wholesalers for Matt:e O-PEN devices.

Installing a 3 phase rapid EV charger?

HappyHippyDad

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pc1966

Julie.

westward10

HappyHippyDad

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pc1966

pc1966

HappyHippyDad

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timhoward

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Gavin John Hyde

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pc1966

pc1966

Risteard

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HappyHippyDad

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3 Phase EV Connection Unit with 4 Pole 32A Type A RCBO

Risteard

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3 Phase EV Connection Unit with 4 Pole 32A Type A RCBO

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