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AC Power Meter | PSU | UPS evaluation | Battery Testers - Chargers | CCTV => Bench-top Single Phase Power Meter => Topic started by: Kiriakos GR on November 12, 2024, 12:32:04 PM
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DCUU PM9913 this is single phase power meter 5kHz Bandwidth, and the most modern and advanced in electronic design instrument at it class.
DCUU PM9913, PM9911, PM9912, background and history:
DCUU brand translates to: Zhongshan Zhongxiang Instrument Co., Ltd, (This is a small factory at China mainland).
This brand, its actually a team of very young people, and Mr. Deng Changguj this is the general manager.
DCUU this is focused at 100% at the domestic market of China, their primary business focus, quality control testing systems for LED lamps.
In their own portfolio, is the development of digital power meter, mainly for production line testing.
PM991x series this were introduced at the beginning of 2017.
This has six active windows, and update rate of 5 measurements per second.
DCUU PM9913 True-RMS AC model 0.5mA ~ 2A (according to User manual)
DCUU PM9911 True-RMS AC model 5mA ~ 20A
DCUU PM9912 this is AC/DC 5mA ~ 20A.
Both 9913 & 9911, they offer identical number of measured electrical parameters.
The named as F LED window, this is a host able to display another four electrical parameter.
In total a number of nine electrical parameters they are measured simultaneously.
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DCUU PM9913 this become my choice, as I wanted to be able to measure Low-Power, Stand-By power.
DCUU its does offer data logging software, for all three models, but under a peculiar requirement.
They are selling (as option) their own communication interface for a connection with a PC.
This communication interface, has a VGA type DB15 as input, and the output it might be RS232 or USB, or RS485.
The converter to USB, this uses CH340 chip and a USB to serial port Windows driver required.
The name of data logging software, this is Electrical measurement system and it operates with the RS232 and USB options.
And in conclusion, at the price of the communication interface, they supply also and their software within a CD media.
Its DCUU instrument, comes with:
1) Quality control inspection card.
2) Calibration Certificate
3) User manual
4) Power cord
And here ends the quick presentation of these instruments.
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This quick presentation alone, it did deliver positive vibes even to me. 8)
Is there a User manual in English?
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This quick presentation alone, it did deliver positive vibes even to me. 8)
Is there a User manual in English?
Yes there is, latest revision November 2024.
Attached.
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I think that I should feel as flattered.
DCUU factory this delaying the shipping, so to provide a power cord with Schuko CEE7/7, to their first European customer . :)
They had to order stock first, so them to be able to provide.
For PM991x series it is essential, the female receptacle IEC 60320 C13 to be right angle * ( So this to not protrude from the instrument).
At the back of the instrument, there is a protruding shield, so to protect all connected wires, even when the instrument this standing upwards.
* right angle by viewing the plug from it back side.
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I think that I should feel as flattered.
DCUU factory this delaying the shipping, so to provide a power cord with Schuko CEE7/7, to their first European customer . :)
They had to order stock first, so them to be able to provide.
So the power cord would be much fresher from the power meter. ;D ;D
I am at teasing mode ;)
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So the power cord would be much fresher from the power meter.
I am at teasing mode ;)
I do not have any proofs about that.
All that I know is, that my order it is packaged to ship at 18/11/2024 ;)
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My order at SUNSKY about PM9913, this including and a few more items.
For savings on shipping costs, I did request instrument carton box, to be used as host for my entire order.
Because of that, I did receive today unboxing photographs from China. 8)
(packaged to ship inspection)
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FLUKE Corporation loves to mention John Fluke and founder, that he started a business from a small garage.
Just of curiosity, I started to decode, the offered calibration certificate by DCUU.
There was an image at top right corner, of this document, and I primarily thought that is some sort, of electrical calibration lab initials.
I did make some hard use of google translate due an image.
The outcome, DCUU has earned, Chinese government award of High-Tech Firm.
And you may get such an honor, after extremely strict and repeatable assessments.
I did contact DCUU today, so to discover of what these first three QC tests, performed by the operator, they translates to?
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DCUU User manual in English, this seems to me imperfect, too many syntax mistakes and neither product specifications looking accurate. :-X
But due this topic, the truth will shine as always and especially when Kiriakos gets his instrument at hand. ;)
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DCUU User manual in English, this seems to me imperfect, too many syntax mistakes and neither product specifications looking accurate. :-X
But due this topic, the truth will shine as always and especially when Kiriakos gets his instrument at hand. ;)
I cannot disagree that their offered documentation, this is poor.
After arrival, this is my to-do list:
a) How many actual ranges for AC voltage?
b) How many actual ranges for ACA current?
c) PM9913 this has a visual indication (due an led) for mA ranges, and I wish to find out how many are they.
d) Calibration inspection due my Fluke 8846A (this is fully capable to inspect Class 0.5 meters accuracy).
e) PC communication due electrically isolated communication converter to USB.
Testing of Low-Power digital power meter, this is a significant challenge, if you do not own a programmable AC load.
Power factor accuracy testing this must be performed with loads of PF 1.0 and PF 0.5
PF 1.0 this is a resistive load
PF 0.5 this is a combination AC load (that I am researching about it, if I can go DIY?).
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Myth busting time
I will start gently with few closeup images of the carton box.
The misspelled DIGTAL Power meter, this is even today printed at instrument face plate, and even at the carton box.
Its now double confirmed, that 99% of DCUU Team, they never when to learn English. :P
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Today I will act as build quality evaluator, and I will stick to essentials.
I can confirm, that DCUU factory, and or their partner whom manufacture the metal case, he does a Spartan use of materials. :P
Electrostatic painting, a tremendously thin layer, at the frontier of is called as acceptable.
Front mask, and push button keys, not made of hard plastic, but from nylon that is a much soften material.
Instrument and four feet, by design there is special location for insertion of rubber pads, that no one bother to add any.
About five brands in China use the same accessory in their instruments, all of them skip the rubber pads.
Power switch, with good mechanical feeling, but the cover key seems as scratched all around.
At PM9913 instrument mask, at B window, only the LED for mA, this is really there.
The Ampere printing bellows the mA printing, and the position for a second LED indicator it’s a decoration item.
At the back of the instrument, there is AC power connector with ROHS, and a spare fuse.
(Panel mount AC power receptacle 10A 250V, a product of HONGJU factory in Dongguan)
This is a certified product and it is exported worldwide, I did find it in stock even in Greece.
About the famous EU power cord, which for this detail, the shipping of my power meter this delayed for a week of time.
DCUU supplied a cable with stray female inlet instead of a 90 degree one.
Yes this cable protrudes at the back of the instrument, and I did replace it with a 90 degree one.
Most irritating detail, the quality of the screws over the case, most found with slightly oxidation (discoloration), and someone repaint them externally with spray paint.
In summary, build quality it is at the edge of the limit of been called as acceptable.
When a factory it is small, when all participants are young and inexperienced, such quality control details they get overlooked without a penalty.
None of these irritations would be there, if production cost this was increased by five USD dollars.
Note: If you look after it enough, it will not gain the look of the industrial worker (last photograph) ;)
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Back plate of the instrument, and wires connectivity.
Nothing found as wrong at the back plate.
The product designer did a good job, panel mount banana, AC input connector, along the AUX I/O port they all have a good symmetry.
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DCUU PM9913 this is based at a single metering chip product design.
And while the actual metering chip, this is in the market for two decades, DCUU indeed it did succeed to use all of it functionality.
At my PM9913 I did performed a significant amount of functional tests, so and I (first person worldwide), succeed to verify and or to better understand actual product design performance.
Test on Frequency counter detection
PM9913 lower frequency detection this starts from 20Hz.
But higher frequency detection this is relative to input voltage level.
Input 26 ACV - frequency detection 20~50Hz
Input 30 ACV - frequency detection 20~60Hz
Input 45 ACV - frequency detection 20~100Hz
Input 80 ACV - frequency detection 20~200Hz
Input 110 ACV - frequency detection 20~300Hz
Input 150 ACV – estimated frequency detection 20~400Hz
Test on Frequency counter linearity
Input 20Hz - reading 20.0
Input 50Hz - reading 50.0
Input 60Hz - reading 60.1
Input 100Hz - reading 100.4
Input 200Hz - reading 201.9
Input 300Hz - reading 304.5
Input 320Hz - reading 325.1
Input 400Hz – not tested
Test on Power Factor detection
As it is proved at Frequency counter detection test, there is a requirement for a minimum input voltage for having best detection (Error Free).
For the power factor, input ACV this must be at 95 Volts, while actual minimum this is 90 Volts.
For my PM9913, Error Free PF detection, this is from 94 ACV and or higher than that.
Test on Voltage bandwidth
PM9913 this is not using any voltage sensing transformer, it is using instead a voltage divider.
By design a resistors network in the form of voltage divider, this is not introducing any phase shift error.
And neither this seems causing any bandwidth limit.
Actual energy measuring chip this has highest voltage bandwidth limit at 1600Hz.
At my tests, I did supply AC voltage at a range of frequencies, and ERROR Free range this is from 20Hz up to 1200HZ (Class 0.5).
Just for fun I did tested from 1200Hz and above, and ultimate end of the road found at 1900Hz.
And therefore actual measuring bandwidth confirmed up to 2 kHz Max.
I am unaware of how or why, DCUU this wrote 5kHz as Max :P
Test on Current sensitivity
PM9913 this is using a sensing current transformer this been rated at 20A/10mA.
Long story in sort, DCUU engineers they are using only a portion of it entire range, and by doing so, they keep at a minimum any linear range error.
Transformer Phase shift error: lesser than 20 degree
Linearity error 0.2%
At my actually testing, PM9913 this is capable sensing from 0.20mA and higher than that.
But for best energy calculation, the input voltage must be at 90 ACV and ACI current input must be from 7.0mA or higher.
Active testing Summary
A Single phase power meter, this is a combination of voltage meter and a current meter along a power calculator IC.
As is know from the world of multimeter, they are a portion of limitations, these be relative to measuring range per electrical parameter, for best accuracy.
DCUU specification of 5V as starting ACV this is verified, but this is valid if PM9913 this is used as this been a voltage meter.
For a proper power in Watts’s calculation at entire bandwidth 20Hz~400Hz, this is possible with an input of 150 ACV or higher.
For Europe and USA, PM9913 this is usable as power meter, with input voltage from 30 ACV and or higher than that.
Error Free Power factor detection at 94 ACV and above, and I will name that as a High precision Mode activation at 20Hz up to 200Hz bandwidth. :)
PM9913 this is able measuring as low as 1/3 of entire power consumption of single Neon bulb.
PM9913 voltage detection this is free of error at sine wave, square wave and triangle wave.
PM9913 when this measuring Stand-by power of pulsing power supply, Power Factor detection and Power measurement this is very unstable.
The solution is the use of PC logging software, so this to record the average measured power (averaging), within a time duration of product testing.
In conclusion, today that I am aware of most of strong and weak points of PM9913, regarding manufacturing quality along electronics performance, and by thinking also the factor of product price, I will say that my money in the form of an investment, they have not been wasted.
For my taste, DCUU this is an awkwardly managed company, product documentation this is extremely inaccurate and poor, website and due internet communication another major problem.
But their products they do work and deliver usable results, when they are operated at by Kiriakos Triantafillou discovered ACV and ACI electrical input levels.
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In summary, build quality it is at the edge of the limit of been called as acceptable.
When a factory it is small, when all participants are young and inexperienced, such quality control details they get overlooked without a penalty.
None of these irritations would be there, if production cost this was increased by five USD dollars.
This mini review and the results, it makes me wonder, of how many similar issues they might hiding at the most expensive single phase power meter? :P
I had long time to read something that interesting.
Thanks mate !
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I will add in the list of good news, that this model has a linear power supply inside.
(According to notes over the power socket)
This translates to a much longer product life cycle, in to my eyes.
And the measurement circuit, this has nothing to worry about any radiated interference. ;)
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In such a complex instrument, it is possible PF LED window and Frequency LED window them to be few counts out.
But what about an actual comparison, of Watt with the VA window.
Does it measure correctly from low to high?
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In such a complex instrument, it is possible PF LED window and Frequency LED window them to be few counts out.
But what about an actual comparison, of Watt with the VA window.
Does it measure correctly from low to high?
I needed three days so to perform my personal calibration report.
I had use 2KVA AC voltage stabilization, my well made Variac transformer, lots of resistors and light bulbs and even ACV power tools.
If any one of our readers has this question, he should donate 25€ at ITTSB so to receive an answer. ;)
No Free food any more, to anyone.
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And therefore actual measuring bandwidth confirmed up to 2 kHz Max.
I am unaware of how or why, DCUU this wrote 5kHz as Max :P
I have a fresh interesting find to share, single phase power meter this is something new to me, regarding specifications understanding.
I got few clues by reading 64 pages, about the in use Power/Energy IC.
Long story in short, the developer of such a power meter, he is responsible to select components these will form a low-pass cutoff frequencies filter.
Additionally this filter it should aloud or have, a pass-band, at a minimum 11 harmonics, of the fundamental frequency.
PM9913 this supports at the upper side 400Hz as a fundamental frequency, and if we add those 11~12 Harmonics pass band, then the total instrument bandwidth this now become 5kHz :)
I did use Excel Worksheet and calculated 400Hz harmonics pass-band, and yes everything line up and now makes sense. 8)
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Today I did run and another test, this answers the question, of what is the recommended warm-up time, so the instrument to deliver best performance.
I did 45 minutes data logging.
While the load a neon bulb, this was active for 90 minutes, so it current at 1.18mA this to be perfectly stabilized.
PM9913 this required 15 minutes, while indoor temperature is at 14 Celsius.
This is impressive, because at higher ambient (20C), this will warm-up much faster.
I will take this as an advantage, this coming due the small form factor PCB inside.
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I wish to return back at Test on Power Factor detection chapter.
Cirrus Logic this is the source of the power meter measuring IC.
Over the past months, I did read a pile of Cirrus Logic documentation, this comes in poor writing, as assistance to any product developer.
The problem is that you have to read documentation about all five IC, at their specific product series, so gather entire amount of specifications.
Also I did contact directly Cirrus Logic, so to get answers, and they shown unhelpful and not knowable about past made work of Cirrus Logic :P
Regarding Power Factor Accuracy the IC has +/-0.2% over 100:1 dynamic range.
For example, when a calibrator feed-in an ACV signal with a Power Factor this be at 0.9000, acceptable PF error this is:
High side =0.9018
Low side = 0.8982
When PF this is at Maximum PF=1.000 with -0.2%
Low side = 0.998 and this is acceptable.
In conclusion, at four digits power factor meter, known error this translates to +/- of three counts. ;)