Originally Posted by emolatur
No joke. That's what it's called... or "center-grounded delta" but that name irritates me since the center of a triangle is just a void.
To put a neutral in the center of the triangle we use the wye system as opposed to the delta system. Then we get the 120/208 and 277/480 volt systems.
Theoretically each of the three transformer windings producing one delta 3 phase system can be center tapped allowing balanced 120/240 volt loads on each of the AB, BC, and CA leg pairs. But in practice this can never be done because only one of those neutrals can be grounded.
A delta system is either high-leg (usually the high leg is designated B) or does not have a fourth wire as a neutral (is 240 volt only in the case of a 240 volt system).