Mobile charger with single phase 240v circuit ground loss

[arorgan]

That is an auto transformer and creates a 120V midpoint from a 240V feed. It doesn't fix the issue of the 240V being referenced to ground.

You are correct - however the UMC requires split phase which is what is needed. The grounding isn't the issue, it's harmonics at this point.

Thanks for getting back to the thread.

 

[Rocky_H]

But does the car/charger even know what 'ground' is? All it sees is three wires, and with luck the middle one is a steady midpoint of the other two. Even in a split phase 240 system the ground may not be absolutely perfect(hopefully it is). In theory, the transformer referenced would provide a very steady center point.

But that's not what the car or cable is looking for. It doesn't have to be a midpoint. You're talking about a neutral, not a ground.

Right and the issue is that some combination of the car and charger wants to see 120VAC on the two line inputs, not 240VAC and 0VAC.

No, that's not right.

I am surprised as to why it needs a split phase.

It doesn't.

it should work in a 240-0 scenario (think Europe/South Korea). People have brought their cars overseas and L2 charging definitely works.

Yes, it does.

You are correct - however the UMC requires split phase which is what is needed. The grounding isn't the issue, it's harmonics at this point.

Good grief! No, none of that is true.

My goodness there is so much wrong here. No, it definitely doesn't have to be split phase, and that third wire that people are trying to figure out definitely DOES NOT have to be at a midpoint voltage-wise between the two "voltage difference" wires.

This can be easily proven just from looking at the simple case of using a standard American 5-15 outlet. The two voltage wires are at 0V and 120V. Is the third wire in the middle at 60V, as some people are claiming it must be? No, it isn't. It's ground, so it's also at 0V, just like one of the two main conductors it's using for power. The same could be done with the two voltage wires at 0V and 240V and the ground also at 0V. Same thing, and the car will operate fine IF that is a real ground.

These devices or methods of trying to create a fake ground may just not be faking it in the way it needs to to meet the criteria that the UMC is using in its ground test.

 

[mongo]

But that's not what the car or cable is looking for. It doesn't have to be a midpoint. You're talking about a neutral, not a ground.

No, that's not right.

It doesn't.

Yes, it does.

Good grief! No, none of that is true.

My goodness there is so much wrong here. No, it definitely doesn't have to be split phase, and that third wire that people are trying to figure out definitely DOES NOT have to be at a midpoint voltage-wise between the two "voltage difference" wires.

This can be easily proven just from looking at the simple case of using a standard American 5-15 outlet. The two voltage wires are at 0V and 120V. Is the third wire in the middle at 60V, as some people are claiming it must be? No, it isn't. It's ground, so it's also at 0V, just like one of the two main conductors it's using for power. The same could be done with the two voltage wires at 0V and 240V and the ground also at 0V. Same thing, and the car will operate fine IF that is a real ground.

These devices or methods of trying to create a fake ground may just not be faking it in the way it needs to to meet the criteria that the UMC is using in its ground test.

If the UMC expects to see only 120VAC max on either phase line (which all US adapters should be), it would need split phase 240.
If it doesn't do a rationality check on the inputs, single phase 240 would work.
Personally, I would do the former as it protects against "ground" which is really a phase.

 

[Rocky_H]

If the UMC expects to see only 120VAC max on either phase line (which all US adapters should be), it would need split phase 240.
If it doesn't do a rationality check on the inputs, single phase 240 would work.

Ah, OK, I'll amend some of my earlier statements. I was focused on what the third pin should be, and it definitely doesn't have to be a neutral or a mid-point between the two voltage pins. I wasn't really thinking of what the allowed conditions of the two main voltage pins should be. But since some other countries commonly do that, I really wouldn't think Tesla would bother with the extra expense and complexity to disallow it for not much reason in the U.S. version.

 

[mongo]

Ah, OK, I'll amend some of my earlier statements. I was focused on what the third pin should be, and it definitely doesn't have to be a neutral or a mid-point between the two voltage pins. I wasn't really thinking of what the allowed conditions of the two main voltage pins should be. But since some other countries commonly do that, I really wouldn't think Tesla would bother with the extra expense and complexity to disallow it for not much reason in the U.S. version.

Yeah, third pin must be ground. And ground is usually equipotenalish to neutral. Using US adapters, that limits what the other legs should be unless on some wye 3 phase derived setup or single phase source.