Thanks for the help.
Here is what I am using.
http://www.avatarinstruments.com/scr/scr.asp
They say power factor is 100%.
There is indeed a mis-reporting of power at low levels but for a different
reason I think. I have an uneven heating load using these controllers on
both sides of a 240 volt genset to the N phase The current sensors are
taking average current, not peak. If they were peak sensors that would
indeed show a gross over reporting at the load decreases beacuse the current
is chopped.
Here is where things take a bizzare turn. From 30% power on up the readings
appear correct usning 1.111 X average correction.
At about 25% power on down going lower let's say at around 10% Things get
ugly, the atcual heating load using true rms voltage measurements at the
load and known resistance it appears to be 250 watts when controls are at
this low setting. I belive that. I should be using RMS sensors I know this
but the error using average sensors is only 1.111 X avaerage.
.. Well guess what happens when I hook up true RMS current meters? It reads
Higher! It says there is 4 amps on L1 and so does my average sensor using
1.111 correction. The current on L2 reads 6.5 but the average sensors
says 3.4! SO the RMS reading is double on this side! In other words it
agrees with one but not the other.
.. This tells me that we have a total of 10.5 amps in the system. Well
that's about 1250 watts. There is no way that load is on the engine. If you
bypass the controllers with a known 1200 watt load you can clearly here the
engine groan. So where is the other 1050 watts of power going or is not
really there? I think it's either there and being stored in one side of the
stator or it's apparent or reactive power becuase there is a phase
imbalance.
Do you see what I see? Here is what I think is going on. As the voltage is
off longer there is more energy stored and there is an imbalance of load. It
appears the stored enegery is being pushed back to the side with lower load
on it and the system is now has inductance or reactive power in it. I think
my rms current measurments prove it.
It is a resisitive load but the generator is bascilly an electric motor and
this is a closed system. Once you start turning off the voltage longer
things go haywire.
Keep in mind that we want the actuaual power to the shaft. If the power
factor was alway's 100 then not an issue. I am no expert but it sure looks
to me like we do have a big power factor problem. I think balancing the load
would help. I guess my question is, just WTF is going on?
I think the best way to deal with this is to correct the power factor if
that is the problem, not try to measure it.
Thanks.