Best service type for EV charging?

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pipe_bender

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Location
Boston
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Electrician
At a campus there is a large parking lot and they want to add 25 EV charging spaces, the EVSE are 12 kW 240 Volt single phase. The question came up if 208V or 277V would be acceptable and the reply was no "all the chargers require 240V" further clarification was that they do not require a neutral "nor any 120V."
There is some LED light poles to add also that can run off anything (120-277), there are no other loads and no building close by.
The site is a primary customer so the utility delivers service at primary voltage and will provide the hi-voltage work from a vault, a separate transformer is required for the EV charging area.
So my question for the group is whats the best transformer configuration for a 240V EVSE site considering losses voltage drop etc?
The only 240V three phase I have worked on is a old very delta, but our suppliers now offer a 240V in a wye in a few configurations some are tailored to VFD's.
Anyone have experience with this what did you choose (or would you choose) and why?
Disclaimer I am not the one selecting this stuff just curious what people are doing around the country.
 
There might be some issues with the ground fault protection built into the chargers, corner grounded delta or delta with the high leg may not work well. Sounds like they are just wanting it put in, and don’t have a clue about what will work. The EV’s will charge just fine at 208, and a lot of problems could be avoided.
 
As others have said 208 is fine we use it all the time, but if you want the most efficient I'd wager 416Y/240 would be it.
Unless there is any reason they cant run off a 416Y/240 ? NEC or SAE J1772 or other EV standards?
Article 625.4 specifies voltages, '240' is one but then it says 'unless other voltages are specified'. I am not sure if it makes a difference inside the EV if the 240 is line to line or line to ground like a corner ground 240 or a 416Y240.
Then you'd have to use 480/277 panelboard but you can use 1 -pole breakers (rated 277V) or feed 3 chargers of a 3 phase breaker each charger connected Line to neutral (4-wire circuit), your voltage drop calcs would then take advantage of the 416V.

EDIT found this thread you'd have to verify the charger can accept 416Y240 or corner ground 240

I have 415/240V transformer. Turns out my loads need 240V phase to phase...

1. single phase 2. the problem is that one terminal is "grounded". i agree with Wayne above that the responder isn't really understanding. 240V is 240V 3. aw man, single phase is what i need 4. i will look into this! 5. let me ask for specs and see what tolerances are 6. that might not be...
forums.mikeholt.com
 
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tortuga said:
As others have said 208 is fine we use it all the time, but if you want the most efficient I'd wager 416Y/240 would be it.
Unless there is any reason they cant run off a 416Y/240 ? NEC or SAE J1772 or other EV standards?
Article 625.4 specifies voltages, '240' is one but then it says 'unless other voltages are specified'. I am not sure if it makes a difference inside the EV if the 240 is line to line or line to ground like a corner ground 240 or a 416Y240.
Then you'd have to use 480/277 panelboard but you can use 1 -pole breakers (rated 277V) or feed 3 chargers of a 3 phase breaker each charger connected Line to neutral (4-wire circuit), your voltage drop calcs would then take advantage of the 416V.

EDIT found this thread you'd have to verify the charger can accept 416Y240 or corner ground 240

I have 415/240V transformer. Turns out my loads need 240V phase to phase...

1. single phase 2. the problem is that one terminal is "grounded". i agree with Wayne above that the responder isn't really understanding. 240V is 240V 3. aw man, single phase is what i need 4. i will look into this! 5. let me ask for specs and see what tolerances are 6. that might not be...
forums.mikeholt.com
Click to expand...
As I said before, the built in ground fault protection will probably not like those voltage configurations.
 
I would go back to the supplier and specifically ask if the following would be acceptable:

240V Line-Neutral derived from a 416Y/240V system (full 240V, but one leg is the grounded neutral)
240V H-H derived from a 240Y/138V system (full 240V line-line, but both legs are 138V from ground instead of balanced around ground)

or if the only acceptable power source is
120/240V H-H (normal 'residential' split phase power).

If the only acceptable power source is 120/240V 'residential' power, then you might want to look at a 'hexaphase' transformer or 3 separate single phase transformers.
 
If you have three phase 416Y/240V, you can have 22 kW chargers if you want to.
 
A high leg delta will be a readily available transformer configuration to simplify grounding, and the delta will mitigate the harmonics from all those switch mode power supplies. Or if it can take 240 volts to ground, a corner grounded delta.
 
winnie said:
If the only acceptable power source is 120/240V 'residential' power, then you might want to look at a 'hexaphase' transformer or 3 separate single phase transformers.
Click to expand...
Or in that case a 5-wire two phase, you could use two transformers, possibly one with 86% tap but I have herd of it being done with two standard transformers.
Interestingly the only other place in the US other than PA that I herd (years ago) still had some two phase was Massachusetts (Pittsfield) so a local transformer manufacturer may at least have herd of it.
You'd have two standard split phase 120/240 feeders one with 12 chargers the other with 13.
Completely within the GFCI spec then and the load would appear balanced on the 3-phase side.
 
tortuga said:
Or in that case a 5-wire two phase, you could use two transformers, possibly one with 86% tap but I have herd of it being done with two standard transformers.
Interestingly the only other place in the US other than PA that I herd (years ago) still had some two phase was Massachusetts (Pittsfield) so a local transformer manufacturer may at least have herd of it.
You'd have two standard split phase 120/240 feeders one with 12 chargers the other with 13.
Completely within the GFCI spec then and the load would appear balanced on the 3-phase side.
Click to expand...
A Scott-T connection. While it sounds cool and would totally be something I might do because I'm a weirdo, it is so far out in the weeds that corner grounded deltas and 416 volt wyes look normal in comparison.
 
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