On 01/03/2020 14:08, Jethro_uk wrote:
On Sun, 01 Mar 2020 13:37:47 +0000, AnthonyL wrote:

Are there any conditions when the phase needs to be known? If so how is
it detected?

If you connect a 3-phase motor up wrong, it won't work. Does that count ?

This has the suggestion of leading to a bridges of Koenigsberg puzzle ...
what's the minimum number of wires you'd need to swap to get it
working

one pair


--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen