This hunting started by me looking up for details of one misspelled electrical standard.
An Chinese brand wrote
BC17215-2002 as standard in compliance of their plug-in power meter / energy / power factor.
And I found nothing about it.
True standard this is
GB/T 17215-2002Alternating current static watt-hour meters for active energy(classes 1 and 2) (English Version)
This standard is only applicable to newly manufactured static active energy meters with accuracy levels 1 and 2 for measuring AC active energy in the frequency range of 45 Hz to 65 Hz and their type tests. This standard is only applicable to static active energy meters for indoor and outdoor use, which consist of a measuring piece and one or more meters installed in the same meter. It is also applicable to one or more working indicators and one or more test outputs.GB/T 17215-2002 superseded by
GB/T 17215.321-2008 Electricity metering equipment (a.c.) - Particular requirements - Part 21: Static meters for active energy (classes 1 and 2)
GB/T 17215.322-2008 Electricity metering equipment (AC)-Particular requirements-Part 21:Static meters for active energy
classes 0.2 and 0.5GB/T 17215.321-2008 superseded by
GB/T 17215.321-2021 Electricity metering equipment (AC)-Particular requirements-Part 21:Static meters for active energy
classes 1 and 2 GB/T 17215.321-2021
This defining power meter Class standards for Classes 0.2 , 0.5 , 1.0 and 2.0
Making a Chinese product according to local standard ( UK for example) this is a need if you plan to export your technology to them.
Unfortunately for us, technology explorers, all standards documentation this comes for a price.
In theory, all such standards for the market of Classes 0.2 , 0.5 , 1.0 and 2.0 AC power meter, they do define measuring precision limits.
measuring precision:
AC Volts range
AC current range
Power Factor range
RMS Watt
etc etc
When such a standard gets replaced by a new, the new its more strict.
Newly developed electronics needed, for the production of fresher measuring instruments.
All products made due the old standard, they cannot be imported any more at the specific country.
Oldest found standard this is GB/T 17215-
1998------------------------------------------------------------------------------------------------------------------------------
About GB/T 17215-
2002 I am aware of acceptable limits for 10A shunt.
Example:
product of Class 1.0
Active Power / Accuracy Class0.2 ~ 1 W / Less than 10
1 ~ 5 W / Class 5 0.2 ~ 1 W 1 ~ 5 W
5 ~ 2200 W / Class 1
RMS Current:20mA ~ 10 Arms / Class 1
Power Factor / Class 1
For : 0.2 ~ 5 W Even or greater than 0.030 PF
For : 5 ~ 10 W Even or lower than 0.030 PF
For : 10 ~ 2200 W Even or lower than 0.010 PF
By combining all the above information's, the specific Class 1 instrument, behaves as Class 1.0 only when our measuring current this is 20mA as minimum.
Then we check Watt power reading.
Final step, we do an inspection if Watt Power and Power Factor are both high enough (among limits ), and then we trust the measurement.
Practical example for Class 1.0 (The load it should be minimum 5W)
Current consumption minimum is 20mA
Volts AC 230
Power Factor 1.0
Total 4.6W = Pass
Another Example Current consumption minimum 20mA
Volts AC 230
Power Factor 0.030
Total 138 mW
= Fail Because its under Watt minimum measuring value.
In conclusion, we need to separate in our head the description as measuring ability and the description of accuracy.
While Watt range might be from 0.2 W and up to 2200W, only when we are within in range of Power Factor that our instrument is capable to measure
accurately, then we may trust the measurement.
For measuring Low power (standby power), the more accurate in Power Factor measuring instrument, this will be the winner.
An instrument with four digits Power Factor its a good start so to be called as modern.
The specific product example with 10A shunt it qualify to measure pulsing power supply only in the range of 5 ~ 2200 W.
This is named as power consumption measurement, but this is nowhere near to Power Standby measurement expectations.
Class 10 instrument, its 10% Error at 0.2 ~ 1 W
Class 5 instrument, its 5% Error at 1 ~ 5 W