Single phase power meter - Calibration verification at 230VAC down to 50mW

[Kiriakos GR]

The usual method so to inspect a single phase power meter calibration, this is to connect it with a real calibrator.

Alternative method this is to own a stabilized AC source 230ACV 50Hz, and to do load testing by using a precision resistor.
Calibration verification of specially designed power meter, for low power this is a more difficult task.   

In my case, I did originally use at my test setup as a load, one special Vishay resistor 1M 4KV 0.25% tolerance.
Such a load testing, this proved or confirmed that my power meter, it does measure down to 52mW at 230 ACV.   

I have at my work bench two DMM with equivalent resistance (impedance) at ACV all ranges, this be at 1M Ohm.
First is the HIOKI DT4282 = 1 MΩ ±4%, 100 pF or less 
Second is the FLUKE 8846A =  1 MΩ ±2 % shunted by <100 pf

With rough numbers in mind, its and every one of my DMM, along my Vishay special resistor, they do create a loading of 50mW.
And I am using the word rough numbers, because these 1M resistors they do not have extremely tight tolerances, and neither the ACV source it can deliver better stability than 45.2mV at 230 ACV output.   
This game becomes more interesting, when I perform power measurements by combining these loads.

And in conclusion I can now perform effortlessly tests at my power meter, at the range of 50/100/150mW
With rough numbers in mind, the actual measurement at the power meter it might be plus ten counts, at the above values which I deliver as an example.

(Calibration verification, Performance Test, AC Power meter sensitivity inspection, no matter the words in use, the above tip it does work.)