In article _kpIb.705776$Fm2.607868@attbi_s04, Loren Coe says...

does anyone have a suggestion as to how i measure this with
just "normal" equipment, including an O'scope? running back
and forth to the utility co.power meter doesn't seem like a
very good approach.

Basically you need to be able to put current and
voltage waveforms on the scope at the same time,
so you can measure the phase angle between them.

I used a Fluke scope-meter, which is totally insulated
so I could simply wire the scope input across the
incoming 240 volt line, to show voltage. Then
to display current, I put a one ohm resistor in
series with the incoming line, and put the other
scope input at the other end of that resistor,
so the trace was an analog for current.

When the motor was just idling, the phase angle
was very, very close to 90 degrees, IIRC it was
about 86 degrees.

You could use two dual input plug-ins on a scope
like a Tek 7000 series, and use the 'difference'
option to show the same thing. Others have suggested
floating a scope chassis via isolation transformer.
Honestly I would strongly suggest NOT doing that.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================