It is generally accepted that a single phase load should not be connected between the neutral conductor and the high leg of a delta transformer connection with one transformer center tapped to provide 120 volts to neutral. Does anyone know how to calculate the current if, for some reason a load should be connected between the high leg and neutral? Assume, for example, that the hight leg is phase C. If Phase A to Neutral is 50 amps, phase B to neutral is 80 amps, and phase C to neutral is 90 amps, what would be the total neutral current?
It, isn't generally accepted that you should connect a load in this manner. For one thing if using circuit breakers on a 120/240 delta you won't find single pole breakers rated for 208 or 240 volts, unless you went into 277/480 series panels/breakers.
Outside of that - current flow I would assume depends on if it is open or closed delta, at least how it flows within the windings.
Closed delta the neutral off a high leg load would split two ways to get back to the high leg output of the transformer.
Open delta it would all have to flow through the closed end.
The other two legs neutral currents do cancel one another just like a center tapped single phase system.
I don't know the math needed to figure the net current on a common conductor to all lines though. I can see it possibly being different for open vs closed delta though. Never really had a formal advanced math class that would help understand this better.
