Which one Digital power meter AC & DC for an electronics repairs lab ?

[Kiriakos GR]

According my recent research, Digital power meter development within Asia and specifically China, this started to boom since 2014 and later.

Single phase Digital power meter known classification according to serving application:
a) AC Mains Plug-in style , plastic body , LCD ........................................................................................... = Home users

b) AC , banana inputs, metal box, 3~5 parameters simultaneously , LED display.................................... =  inspection of machinery.
c) AC , banana inputs, metal box, 3~5 parameters simultaneously , LED display, programmable ALARM =  inspection of machinery / permanent monitor 

d) AC , banana inputs, metal box, 4~5 parameters simultaneously, ACV 600~1000 20A, Large motor, harmonic content, PC connectivity = Basic tool for R&D high power analysis
e) AC , banana inputs, metal box, 4~5 parameters simultaneously, ACV 600~1000 2A, TFT screen, harmonic content, PC connectivity = Basic tool for R&D Low power analysis   

f) AC & DC, banana inputs, metal box, 4~5 parameters simultaneously, 600~1000V 20A, Large motor, DC load, harmonic content, PC connectivity, single or more channels = AC & DC Basic tool for R&D high power analysis 

g) AC & DC, banana inputs, metal box, 4~5 parameters simultaneously, 600~1000V 2A, TFT screen, harmonic content, PC connectivity, single or more channels = AC & DC Basic tool for R&D Low power analysis.

And by this quick description, we have now a list of the 90% of  available Digital power meter at the year 2021.   
The other 10% these are product solutions at very high prices,  these come from known players in Japan, them competing its other, of whom will follow first the latest trends so to serve market sectors as is automotive, aerospace, power meters calibration.

Here comes the question: Which one Digital power meter AC & DC for an electronics repairs lab ?
This is a sector that we need primarily tools classified as:  AC & DC Basic tool for R&D Low power analysis.

Primary list of applications / requirements:
Standby power measurement = Power factor calculation with minimum error.
Watt power measurement at 230V = 1200W down to 0.001W
Harmonic content review: no lesser than 30~40 harmonics = large bandwidth
PC connectivity and relative logging software. 
Fast sampling rate

Secondary list of applications / requirements: 
Mixed evaluation of AC & DC power circuits
Minimum DC bandwidth 20kHz
Voltage and current Waveform review
Faster sampling rate
Largest bandwidth

   
In summary
While power analysis this can go up to scientific level, we should never forget that our actual needs they are down to product functionality verification.
Primarily we need accurate measurements in Watt and Power Factor.
And also the same expectations exist for the DC component and parameters, because when you do DCV circuit evaluation, at Real time with DC load parameter this changing rapidly, an very slow digital power meter, this is useless.

Other instruments as for example (low cost) programmable digital DC load, by design they are unable at varying DC current within an session, and therefore the measuring speed (sampling speed) this is of low importance to them.
The opposite example here is the SMART or Advanced programmable digital DC load, them able to simulate several DC load conditions, these they also come with fast sampling at their measuring circuit, so them to deliver more realistic VA calculations.

Additionally, speaking of accuracy at Digital power meter AC & DC, it is also of importance their bandwidth at AC component alone and at DC component alone.
An good look at its one measuring product specifications,  it can demonstrate clues of product development age.
Economy made but fresh ones digital power meter they come with bandwidth of 5kHz, when high-end power analysis tools they are now offer up to 100kHz of bandwidth.

Bandwidth this is of great importance when a digital power meter, this is capable to offer harmonic content review.
Power calculation electrical standards they are renewed frequently, and they are many.

Harmonic content review at bandwidth of 5~10kHz this is now almost outdated.
Modern tools at 20kHz or 50kHz of bandwidth, these worth today named as  Min/Max limits for entry level professional R&D choice of equipment to buy.
 

[Kiriakos GR]

Chinese market of Digital power meter at the microscope.

Research in depth, of whom makes what today in China, this is now by far more difficult by the use of web search.
A new poor fashion at webdesign, this is to blame for the use at product presentation web page, this solely made of pictures, instead of regular text (product description / features) and product pictures.
And because of that our western web search engines, they are unable to discover traces of new products.

The more serious manufacturer, them whom care for exports, they do use regular web design techniques, the ones which cost more, in time and money, but another problem appears here too.
Trading channels within China, they also use product model description in their web pages, and their number this is a much greater one.
And therefore it gets much harder the ODM factory, this to be discovered by new potential retail buyers and or due NEW Europeans and potential business partners.

Chinese factory in denial to gain CE and west world certification's.
Human life this is full of different scenarios, and products marketing this is not any different in Asia.
I did discover for example a digital power meter this be advertised at ODM page, along with garage doors and garden tools.         
   
First factory this named as (XXX1) for example, this appears to be developer of Metering Systems on a Chip - SoC 44pins, along of PCB, that is a complete product, since 2017.
This (XXX1) brand also developed relative data logging software, but entire range of  their products, this is at the limit of 5kHz of bandwidth, and they get sold as Low-cost solutions.


Second factory this named as (XXX2) for example, this appears to be digital power meters developer since 2004, it appears as rather more experienced, and he does monitor the market of Japanese relative products, even so his best product solution today (LED display), this is what Japan designed 10 years ago.

Third factory this named as (XXX3) for example, this appears to be digital power meters developer too, starting date unknown, this is rather lesser experienced,  aiming sales at lower price, by the use of ancient technology, that is digital power meters at lower than 5kHz of bandwidth, and slow in sampling rate.

Neither any of these three examples, they do care to gain CE and west world certification's.
In other words, they made a choice, business expansion within China borders only, and a such business strategy this is accepted even from us the westerns.
But this concept translates, that we westerns we are also obligated to ignore them for ever, at least us professionally working ones.

Home users and hobbyist will never stop aiming to buy not-certified, low-cost gadgets, but their buying habits they represent a tiny minority.         

[Kiriakos GR]

Within the year 2023, Switched-mode power supply inspection, this is now require 300kHz of bandwidth (fresh made power meter).

Due the latest requirement, several past made AC power meter they are not considered any more as cutting age

An very interesting new find, this is pricing of (four window) AC power meter at China mainland.
Basic model 45~65Hz 5mA~20A = 60 USD  (display update 0.5S)
Basic model 45~1kHz      0~2A = 400 USD   (display update 0.5S)
Basic model 45~10kHz 5mA~20A = 700 USD   (display update 0.1S ~ 5S)
Basic model 45~100kHz 5mA~20A = 1400 USD (display update 0.1S ~ 5S)

Back in time, and for VFD industrial motors only, it was available several basic power meter at the range of  45Hz~400Hz and with current ranges of 2A, 5A, 10A, 20A.

Practically this is the problem with all power meter (four LED window appearance). 
You need to waste lots of time so to discover if this is useful for your needs. 

In summary, this is latest (2023)  quick reference of bandwidth VS application for you.
45~65Hz = toaster , plain AC motor, Incandescent light bulb
45~400Hz ~ 1kHz= industrial motor
45~10kHz = latest LED bulb
45~100kHz =  Switched-mode power supply  (acceptable power measurement)
45~300kHz =  Switched-mode power supply  (acceptable power measurement along full harmonics range inspection) 

Yes we are still talking of four or five window power meter, any advanced measurements they become visible due PC-link and relative software.

(Next class step up, this is power analyzer with dedicated screen, and a pricing which only organizations can afford.)