Currently my most sensitive regarding detection AC power meter, this is Benetech GM86 EU.
GM86 (10A) this has been proven sensitive enough for measuring down to
0.1W but when Power Factor this is at least
PF 0.100 and or higher.
Due this observation, I did started a fresh research, and I am now perform testing at the limits of regular EU plug-in power meter with 16A shunt.
For several months I had the wrong impression, that AC power meter detection this improves when the power meter, this has a shunt for lower ranges.
For example that a 5A shunt this might assist at power meter detection, in comparison to a 10A shunt.
Now I am starting having proofs, that at economy priced power meter, and especially for low current measurement, AC current measurement fails when AC load this has a very small Power Factor.
For example:
230V , 5mA , PF 1.000 (resistive load) = The low cost instrument will succeed completing a measurement.
230V , 5mA , PF 0.100 (non linear load) = The low cost instrument will succeed completing a measurement.
230V , 5mA , PF 0.010 (non linear load) = The low cost instrument will
FAIL detection.
Failed detection this further explained:We do not know much, of how a low cost instrument, this uses voltage sampling and current sampling along Power Factor detection so this to complete a measurement.
We only assume that voltage and current measurements alone, these are enough so the power meter to perform a calculation in Watts.
When we have the cheapest EU plug-in power meter 16A, with only three digits for Power Factor, and a poor product documentation, we cannot see the unseen.
The unseen this is actual product limits at Low Power Factor detection.
When Power Factor detection this Fails,
the meter will not display AC current at all.Power measurement sequence this appears to be:The internal IC (chip) this will start with Voltage detection + Current detection + Power factor detection, and if one of them fails? (due in hardware imitations).
The instrument will display only voltage detection at it LCD screen.
I am now in the route of DIY, so to make one 47K ohm resistive load, this able to operate safely at 230V, and this be at high Wattage, so this to be unable to overheat.