UTE9811+[/b] the instrument adopts the PLL method, which can accurately calculate the total harmonic distortion (THD) and each harmonic value of the voltage and current.
UNI-T documentation this is currently a bit unclear, of actual ADC bandwidth, but it does mention it adopts high speed A/D transformer and
32-bit MCU operation.
After of several weeks of web research,
I did explore entire China mainland and sources which also selling the
AC power meter 9811, and I did discover the entire truth.
AC power meter 9811 this is
an electronic design that many Chinese brands trading since the year
2016. While THD measurement along Harmonic review, both functions belong at the list of strong points, something does not smell nice when we inspect the specification of Accuracy of Harmonic.
Accuracy of Harmonic ±( 0.3% range +5% reading+1 character )=
±(5.3%)
The ADC story: At my search one source mentioned that this design uses ADC able for 8k/S = sum of 8000 levels.
These power meter actually using two ADC, one for voltage sampling and one for current sampling.
12 Bit ADC = 4096 levels, and therefore the use of two 12 Bit ADC = 8192 in total levels per second An third detail that UNI-Trend
totally forgot to add in their documentation,
this is bandwidth of 5kHzLet's glue all pieces together and now we have a pair of
12 Bit ADC with bandwidth of 5kHzTruly I am somewhat very disappointed, because THD and Harmonic functions comes both with very relaxed accuracy specification.
There is no chance some one to be able to compare factory DUT specification about THD and Harmonic, when the comparison point this was measured with tighter in accuracy power meter.
One third manufacturing source, this mention
9811 as in compliance with
IEC61000-3-2. True it might be with
4th edition: IEC 61000-3-2:2014, which this is now obsolete.
Latest is
5th edition: IEC 61000-3-2:2018------------------------------------------------------------------------------------
In summary, today UNI-Trend brag for fast performance this delivered at fraction of the cost VS the expensive power meter.
Accuracy of Voltage 40Hz≤f≤70Hz:±( 0.4% reading+ 0.1 range+1 character )
Accuracy of Current 40Hz≤f≤70Hz:±( 0.4% reading+ 0.1 range+1 character )
Both combined
this is 1% of accuracy for
VA = (Not impressive).
Class of 5.3% accuracy for THD and harmonics = ( way too relaxed) target set by
Energy Star 6.0 for Computers, we need to measure THD this not be higher of 2% at DUT equal or less than 1500W.
According my
nowadays understanding, and after reading lots of bibliography about the expensive meter, 9800+ series this has weak hardware regarding measuring precision.
16 Bit ADC this would be a much better choice instead of 12 Bit, since 2008 the expensive meters using 16 Bit ADC, and we now count 15 years passed since 2008.
UNI-TREND software, This currently including support (profiles) for
UTE9811+ along
UTE9802+ (AC/ DC /AC+DC(T-RMS)
Final judgment if
UTE9811+ and it 32 bit Digital Signal Processor (DSP) this is able to save the day, this will discovered only when at 100ms sampling, the software will be able to log
a minimum of eight VA measurements per second.
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The hart and soul of UTE9800+ Series, this is ATE (Automated Test Equipment), originally designed to be attached at factory production line, and High/Low alarm settings these added to notify the operator, in case that a product does not meet power consumption specifications (automated quality control inspection = QC).
The grandfather series this was
UTE1010A 8 Bit DSP along double 8 Bit ADC ( no support of Windows PC link).
UTE1010A series never sold out of Asia, and become EOL at the year 2018.
UTE1010B (10A Max) and
UTE1003B (3A Max), these it was promising PC link connectivity, but no one ever seen this combination in action.
In theory 1010B model of higher resolution this should include somewhat of better DSP along ADC than base model 1010A or 1003A.
But Internet this is empty of any details confirming any electronic design superiority, because 1010B along 1003B both were extremely overpriced.
And actually
four times higher the price of UTE1010A basic version, and
this unreasonable pricing this killed the love.