My iotawatt displays the power factor alongside the watt consumption only for large watt usage and in case of lower watt consumption, there is not power factor displayed. What is the reason. My next question is how much accuracy we will get from iotawatt when comparing the reactive power in var? Is it safe to say that the accuracy is close to the watt consumption. I have an application where the monitoring of power factor is vital. So, I need to know how much accuracy we will get from iotawatt from power factor prespective.
Thanks in advance for your great support
ioTaWatt is not a power quality instrument. The reason that metric is not displayed below 60 Watts is that I too have no idea how accurate it is at those low current values. If you want to see it on the status display, just create an output to display it.
Var is computed from Watts and VA using the Pythagorean theorem. Again, I don’t have any standard to test this metric at low levels. I’ve looked at the total VARh in a large industrial setting vs the utility meter and found it to be reasonably accurate, but again, I have no equipment to evaluate at low levels.
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Thank you for your support. I am testing the iotawatt with different loads and reactive powers. I used a certified meter as the reference. When completed, I let you know about the results and accuracy. Do you have any idea about the minimum resolution of watt measurments or current? What is the lowest current that iotawatt can measure?
That’s a very subjective question. Assuming it could be clarified with at least some accuracy parameters, my sense is that it would very much vary with many factors including:
- What is the CT range and sensitivity?
- What is the AC waveform?
- How much noise is introduced into the system?
I haven’t explored this very much. Anecdotally i can usually see a somewhat accurate measure of a unity power factor load down to 10 Watts or less at 120V 60Hz. So that would be about 80mA RMS.
Probably could do better with a high quality 500 turns CT and a 10 Ohm burden.