On Fri, 3 Mar 2017 18:37:52 -0600, Dean Hoffman
wrote:

On 3/3/17 4:28 PM, wrote:

There is no "phase issue" at all. There is no such thing as "two
phase" power, at least not in common North American use. All 120
volt power in north american distribution systems is derived from
center tapped 240 volt single phase transformers except in a 3 phase
distribution system, where you get 120 and 208 (120 across 1 phase,
and 208 across 2 phases of the 3 phase supply).

The REAs in rural Nebraska also supply three phase power to
irrigation well motors. I've seen center tap delta which is basically
double what you referenced. There is the Y configuration, 277 volts
each line to ground. Lastly is the corner ground delta. Two lines read
480 to
ground, the third line reads 0 to ground. All of those read 480 line
to line.
Some grain bin drying systems are wired with the three phase you
mentioned.
That lets the electricians use common 120 volt controls. There is also
enough
power with the three phase to run drying fans.
That is true - there are MANY other "industrial" voltages - and 3
phase Delta or wye .
However, in "residential" systems, except in some larger MURBs, it is
exclusively 120/240. In those MURBs, 120/208 3 phase..

All this "non-standard residential" has NOTHING to do with converting
a 240 volt compressor to 120 volts - because ALL 240 volt systems -
even in europe behave the same (with the exception it may be 50hz
instead of 60) and a motor connected for 220/240 will work on any 60hz
240 volt circuit. By reconfiguring for 120 volts it will require twice
the amperage. If, in the extremely unlikely case, the motor is 240
volts only and can not be reconfigured, the cheapest solution (and
simplest in most cases) is a replacement motor (assuming a belt driven
standard compressor - not too many 240 volt integrated oil-less
compressors on the north american market)
If this is a european market compressor brought to North America, all
bets are off.