In to the market of bench-top direct input digital power meter analyzer, there is allot of bragging about sensitivity at lowest AC current range.
For example a manufacturer he might say at product specifications, lowest measuring current this is 25uA at 5mA range.
If this statement is true or false, only a Multi function Calibrator this is able to prove.
Fluke 5730A Multi function Calibrator this is our 21st century tool-pack
(2015 Fluke Calibration).
According to
5730A datasheet, lowest AC current range is
0 ~ 220 uA, and minimum output this is
9 uA.
While at higher ranges, 2.2 mA, 22 mA, 220 mA, minimum output this is 10% of the range.
Resolution ..................................................11,999 counts
ACA Frequency ranges:
40Hz ~ 1 kHz
1k ~ 5 kHz
5k ~ 10 kHz
At the side of AC voltage, minimum range this is 2.2 mV AC, minimum output not specified at FLUKE documentation.
It might be 10% of the range ? , listed resolution 10uV at 2.2mV range.
Power Factor resolution: 0,1 up to 1
https://us.flukecal.com/blog/when-and-why-should-you-upgrade-your-5700a-or-5720a-calibrator