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

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tecorp

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I have an electrical distribution system at 480V 3p3w that feeds a 480V 3P to 150kVA 415/240V 3P4W transformer that feeds a 415/240V distribution board that feeds EV chargers. The problem is that the chargers require 240V phase to phase and we have 240v phase to neutral. The charger manufacturer is saying this is unacceptable. What are some solutions for this?

I am thinking we swap out the transformer to a delta delta if that even exists. Any input would be appreciated...
 
Most EV chargers will work on 208 also, so a 208/120 wye would also work. Verify with the controller manufacturer. Some controllers require a neutral (120 volt electronics) so a delta may put you back to square one.
 
hillbilly1 said:
Most EV chargers will work on 208 also, so a 208/120 wye would also work. Verify with the controller manufacturer. Some controllers require a neutral (120 volt electronics) so a delta may put you back to square one.
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Thanks! I will ask about that. We don't need 120V for any controllers.
 
LarryFine said:
Sounds like you need a 480v delta to 240/136v wye transformer.
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Depends on why the manufacturers says that a 240V L-N supply is not OK, buy 240V L-L supply is OK. Maybe they have some internal parts that are rated for only 120V to ground--then the 240Y/136V option wouldn't work.

I'd be curious to know what the actual issue is with these EVSEs and a 240V L-N supply.

Cheers, Wayne
 
This is their reasoning for not accepting the neutral connection:

"The station will not work if it isn't connected to two lines and a ground. There would be Hardware & Earth faults that would keep the station from functioning".
 
Post a link to the charger manual so that we cam see what it actual requirements and acceptable yoltage tolerance range is.
 
tecorp said:
"The station will not work if it isn't connected to two lines and a ground. There would be Hardware & Earth faults that would keep the station from functioning".
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98% sure the responder is confused and didn't understand the system configuration you proposed.

Cheers, Wayne
 
Before buying any transformer, confirm it with the charger manufacturer.

1) Are these chargers 240V single phase or 240V three phase?

2) Is the problem that you need 240V three phase, which can't be supplied by your existing transformer, or is the problem that one terminal of the 240V is grounded?

3) 480V:240V delta:delta transformers are standard. However if you go that route you need to consider grounding. A common way to ground a delta:delta transformer is called 'corner grounding', where one of the phase terminals is grounded. This would be fine if 240V three phase is what you need, problematic if your system can't tolerate one terminal grounded.

4) A 480V to 240/136V wye transformer is a standard by uncommon type of drive isolation transformer. This will give you a perfectly balanced 240V three phase system.

5) A 480V to 208V/120V wye transformer is one of the most common types of transformer available. If your chargers can tolerate the reduced voltage, then it is probably one of the best choices. It may be that the chargers can use 208V at reduced power rating.

6) If your chargers need 240V single phase, you might be best served by having 3 separate 480V:120/240V single phase transformers.

-Jon
 
Out of interest where did the 415/.240V unit come from? In UK 415/240V was common here.
 
hillbilly1 said:
I think it might be an issue with the built in ground fault detection in the unit. A fault on the grounded leg would probably screw with the electronics.
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I'm assuming these are EVSEs. They should provide downstream GFPE-type protection (CCID20, say). But that shouldn't care about the L-G voltage or if one of them is 0V.

They may (should?) also have an EGC assurance test, in which they intentionally try to pass current L-G (but not too much, as they aren't supposed to trip upstream GFCI). So if the L they use for that is actually N, there would be no voltage difference to drive a current, and the test would presumably fail. That problem can be avoided just by figuring out whether they use L1 or L2 and landing the N supply conductor accordingly.

There's also the issue that the EGC assurance test may be designed around 120V L-G. So something might go wrong if provided with 240V L-G. E.g. a component gets more voltage or more current that it is designed for. That would be a deal breaker. Of course, the circuit could easily have been designed to handle both 120V and 240V L-G, but if it has only been designed for 120V L-G, then that's moot.

A final possibility is that the EGC assurance test will work fine at 240V L-G, but that it will pass twice the current intended, potentially tripping upstream GFCI. In which case it would only work in an installation design where upstream GFCI is not required.

So apparently I was also at least 48% overconfident in my first response. : - )

Cheers, Wayne
 
tecorp said:
This is their reasoning for not accepting the neutral connection:

"The station will not work if it isn't connected to two lines and a ground. There would be Hardware & Earth faults that would keep the station from functioning".
Click to expand...
It is possible they are referencing ground in their controller, maybe like dimmers and timers used to do or with some type of filtering. They may also be confusing grounding and grounded, but Europeans are usually good with their terminology.
 
Besoeker3 said:
Out of interest where did the 415/.240V unit come from? In UK 415/240V was common here.
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Electronic switched mode power supplies are often rated from 100 to 250V so they can be used across the world. You can have a higher density of power supplies on a 240V system rather a 120V one, so large data farms started to install 415/240V systems. This lets them keep the advantages of a Wye but still feed off-the-shelf 240V equipment. This has been going on for almost 20 years now. The use of universal equipment allows their data center designs to be similar though they are in different countries.
 
winnie said:
Before buying any transformer, confirm it with the charger manufacturer.

1) Are these chargers 240V single phase or 240V three phase?

2) Is the problem that you need 240V three phase, which can't be supplied by your existing transformer, or is the problem that one terminal of the 240V is grounded?

3) 480V:240V delta:delta transformers are standard. However if you go that route you need to consider grounding. A common way to ground a delta:delta transformer is called 'corner grounding', where one of the phase terminals is grounded. This would be fine if 240V three phase is what you need, problematic if your system can't tolerate one terminal grounded.

4) A 480V to 240/136V wye transformer is a standard by uncommon type of drive isolation transformer. This will give you a perfectly balanced 240V three phase system.

5) A 480V to 208V/120V wye transformer is one of the most common types of transformer available. If your chargers can tolerate the reduced voltage, then it is probably one of the best choices. It may be that the chargers can use 208V at reduced power rating.

6) If your chargers need 240V single phase, you might be best served by having 3 separate 480V:120/240V single phase transformers.

-Jon
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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 feasible since that would need another distribution board plus the 3 transformers and feeders to each haha
 
MTW said:
How many chargers do you plan on connecting to your supply system? In one location or several?
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17 in total, all in one location. they each have a separate circuit coming from the same distribution board
 
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