Deane Goltermann Oct 20, 2018:

Neutral point is what these gizmos create...I found the one reference (another click on the bilingual source gets you to https://www.btbplaza.com/index.php/en/transformers/88-specia... ) searching "neutral point" + several other terms.
This reference states "A return path for earth current is needed to protect a system against earth fault currents. Earthing transformers, sometimes also called neutral couplers or grounding transformers, are used to create an artificial neutral point in a three phase system, which provides possibility for neutral earthing."

Ideas for more reading...

jeffrey engberg (asker) Oct 20, 2018:

nuetral-point I also see this term.