goldbrick wrote: ↑
Mon Nov 22, 2021 11:46 am
So....if the neutral was connected for 240V, the 2 hot phases would cancel and there would no neutral current (even though it was connected).
The On Board Charrger has only two AC input wires, and Jl772 only has two AC pins. So there is no way to connect two phases (hots) and a neutral.
208VAC doesn't have to be from a Y connected 3-phase system (with the centre point of the Y grounded). 208VAC can also result from the high leg delta
connection (using L3 and N). I actually thought that this was the common way for a 3-phase transformer to be connected in the US. But perhaps it's only common in industrial settings.
As far as I know, the OBC doesn't care what voltage the two inputs have with respect to ground, as long as when a high impedance is connected to ground, a small current can be detected. In other words, the car will reject a floating supply, because then a GFCI won't work. I don't know if the car only checks one input or both for current to ground. [ Edit: one input is usually labelled L2/N, so I guess the car only tests for current from L1 to ground. ]
The image below (from the Wikipedia link) is practically a phasor diagram of the high leg delta, with each side of the triangle representing 240VAC. You can see that the distance from L3 to the centre tap is a little shorter than the sides of the triangle; a little trigonometry shows that it's sqrt(3)/2 (=0.866) shorter, and 0.866 x 240V = 207.8V.
[ Edit 2: On further thought, if the transformer is connected as above with the high leg delta arrangement, then you have 240V readily available (using any two phases), so there is no reason to use 208V for an EVSE. ]
2012 Leaf with new battery May 2019. New to me June 2019.