On 13 Jan 2016 01:27:48 GMT
"DoN. Nichols" wrote:

On 2016-01-12, Leon Fisk wrote:

I was only an "apprentice" but 30 years ago we just hooked up the
equipment and noted the direction. Once we had a really expensive
plastic injection machine. That was a bit nerve wracking. We had one
of us watch a motor and the other give it a quick bump on/off. We had it
wrong of course, switched the wires around, it worked okay yet...

That works for that. We had a big DC power supply 50 VDC at
*lots* of current which was fed from three phase, and the manual warned
that connecting it backwards would instantly destroy the warranty (and
the device).

This was a somewhat new plastic injection machine. I say somewhat new
because it was rolled over onto its side when the riggers were bringing
it in. Customer was none to happy with that. So the machine already had
a "story"...

Our obvious concern was that the machine had a good sized hydraulic
pump on it, run by a three-phase motor. Hydraulic pumps don't always
like to be spun in the opposite direction... We got away with it, at
least long enough to determine direction of rotation. Even if we had had
a direction determining meter/device I don't know how we would have
correlated it with the machine wiring at the time...

I remember whole shops getting thrown out of whack, rotation gone
backwards after the power company had done work somewhere on the
incoming power lines down the street. Oops!

--
Leon Fisk
Grand Rapids MI/Zone 5b
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