Vaddy Peters Jan 14, 2013:

An autotransformer has one winding with taps. Other types have separate windings. There's no need to call them "split" ones. I can't find any satisfactory explanation of either "split-winding" or "с расщепленной обмоткой". Multy-winding and sectioned are a common thing.

Alex Marshall (asker) Jan 14, 2013:

Thanks for your help

Alex Marshall (asker) Jan 14, 2013:

It's called... a separate winding transformer: http://www.electropedia.org/iev/iev.nsf/display?openform&iev...

Vaddy Peters Jan 14, 2013:

You haven't provided more info and the source of it.
http://www.dotix.ru/index.php?r=19&nid=46&page=6
Трансформаторы с расщепленными обмотками НН позволяют присоединять несколько генераторов к одному трансформатору. Широкое распространение такие трансформаторы получили в схемах питания топливно-энергетических станций, а также на понижающих подстанциях с целью ограничения токов короткого замыкания.
This may be understood as there are several primary windings, not just one winding divided into several interconnected parts. Still it speaks about НН which is understod as "secondary".

Alex Marshall (asker) Jan 14, 2013:

Re: split winding transformer This was my first thought, too, but somehow I remain unconvinced by the 87 matches that Google returns for "split-winding transformer" (be sure to click through till the end from the initial 92,000 hits, and they dwindle to 87, most of them originating from China).