On Sat, 21 Nov 2009 13:50:01 -0800 (PST), N Morrison
wrote:

On Nov 21, 9:59*am, Jon Anderson wrote:

For my eventual move to Oz, I will be building my own motor/generator to
power those tools that cannot be converted to 3phase.

Why? They have AC in Australia you know. 415 V - 3 phase, 240 V single
phase, all 50 cycles. How will a generator help?

Yes, but some tools are built for US Power Only - for residential
straight 120V 1-Ph or 120-240V 1-Ph center-tap neutral, and for light
industrial it could be 120/208V Wye 3-Ph, 240V 3-Ph Delta or Open
Delta, 277/480V 3-Ph Wye, 480V 3-Ph Delta. All at 60 Hz.

Some gear would be expensive or imposible to convert to Austrailian
power directly. AIUI, you use straight 240V 1-Ph or 240/415V Wye
3-phase. AT 50 HERTZ, which is the big bugaboo for electronics gear
and certain heavy machinery that can't handle 50-Hz natively.
Transformer cores and motor laminations have to be built differently
to handle both.

You can use a bank of transformers to drop 240V to 120V or 415 to
240V, or boost 415V to 440V, but changing the frequency with enough
energy to run machine tools is a huge issue - that calls for specially
built Motor-Generator sets that have a gearbox or rotating field to
boost the frequency, or a big Variable Frequency Drive just to bump
the frequency up.

There is gear specifically built to run on "World Power" I.E. it is
not frequency sensitive and has multiple input voltage taps to handle
almost anything you throw at it. But they are the exception in the
marketplace, and rarely found used at reasonable prices.

(You have to find a seller who doesn't know what they have, or is
highly motivated to sell fast.)

If he has an engine driven generator set, it's simple to make 60-Hz
power to run the shop gear. Just feed it fuel and air, and the
occasional oil change. The tractor driven PTO generators are even
easier, because the Prime Mover can be changed easily when it breaks
or wears out.

-- Bruce --