Phase displacement can be measured with an oscilloscope. I use 1 turn of heavy wire around the
winding core of a 12:120 Vac transformer and read the voltage scaled current waveform on either the
primary or secondary of the transformer. The resulting waveform can be displayed on 1 channel of
the scope at some conveint size determined by the scope's calibrated vertical amplifier. Place a
voltage divider across the leg under measurement and display it on channel 2, with the two waveforms
dispalyed in the same "size". View both waveforms on a common timebase and read phase displacement
between the traces. Make sure the scope is powered through an isolation transformer.

Bob Swinney


"willray" wrote in message
...
On Jan 11, 2:02 pm, "Robert Swinney" wrote:
Willray sez:

"(of course, half the reason I'm doing this at all, is for the
amusement of it, so entirely reasonable suggestions along the lines
of "do it the smart way", will end up deprecated in favor of
suggestions for byzantine but functional :-)"

Depricate as you will . . . but the method of voltage balancing rotary phase converters as
outlined
in RCM over the years is probably the best way to go. See articles in www.metalwebnews.com which
describe the voltage balance method in detail.

Bob Swinney

This isn't the first rotary I've built or balanced - just the first
that I decided to incorporate a full monitoring package into, so that
it can draw pretty pictures on my 4-channel scope. The availability
of 4 channels provides some visualization and monitoring capabilities
that aren't typically taken advantage of by the RCM techniques.

Fitch and Jim R. seem to be the people who have done spent the most
time staring at scopemeters hooked up to their converters, but they
were stuck with the Fluke's dual-sweep inputs, and weren't really
working for designing an available-full-time monitoring system.

In the end, it'll end up balanced just as normal, but it'll be more
fun doing it, and it'll draw pretty, and moderately meaningful
pictures for me :-)

Will