In my business I come across old German equipment with 3-phase induction
motors that are connected in Y-configuration to start and within a few
seconds switched to delta for running. This is done, I'm told, to lessen the
inrush current at switch-on.

Typically the motors have 3 independently-wound windings with 6 connections,
both ends of each winding are brought out to the terminal block.

I'd like to understand a little more about why this works. Is it as simple as
the fact that between 2 supply phase connections in the Y configuration there
are 2 windings and in delta there's only 1? (The Y configuration's common
point is not connected to ground or neutral.)

Thanks,
--
Al, the usual