Mains Quality Measurement System  - Page 1
Forum section: electronics / general

author: JoHr
author_rank: Regular Contributor
timestamp: January 12, 2023, 08:53:59 pm
content: Hello Folks,I´m doing a data acquisition project on qualifiing the mains parameter.Its running since one year now. Exclusivly with frequency measurements.You can find published data, multiple analysis and some variations of displaing data here ...http://vanhinten.de/Now I´d like to move forward and check more stuff. I did a quick shotwith an oscilloscope and a high voltage differential probe (HVDP) and logged for a few dayssome voltage data. Its worth to log them continuosly as well.An HVDP with ADC and Raspi backend is already designed to get rid of the oscilloscope and expensive probe.For analysing voltage I´ll take a look atVpp, RMS, Mean, StdDev, Crest, Rise/FalltimeHarmonics (20)Especially harmonics is a well indicator of when the mains get dirty by unregulated load.Furthermore is planned to do a kind of software triggering to get each period which I´d like to pass through a mask test to getkind of runts or interrupts in periods. Those events shall be logged with their timestamp and characteristicsas I did for frequency data.What do you think would be worth to be logged as well?Main focus yet is logging data. Analysing them is another part.maybe three loggers at the same time on the three-phase current system?with measuring phase to each otherThanks for hints and ideasBR JoHr

author: Hawaka
author_rank: Regular Contributor
timestamp: January 12, 2023, 09:16:48 pm
content: There is a lot of data that you can extract from just the voltage. Have a look at commercial power analyser, you'll get a lot of inspiration. Most of the time the manual is free to download so easy to see what they do. In addition have a look at EN50160 to see what are the parameters that matters for the grid supplier.Check outhttps://www.a-eberle.de/,they have a lot of product that could interest you. Especially the PQ Box (https://www.a-eberle.de/produkte/the-mobile-tool-for-the-expert-pq-box-200/?lang=en). Dewesoft (https://dewesoft.com/) also comes to my mind and ZES Zimmer (https://www.zes.com/en). ZES also include the exact way in there manual on how they calculate each value, worth to have a look. A fluke 345 could also be interesting, but it's a simpler device.Regarding data logging you could save each point of the measuring but that will very fast be a lot of data. The best would be to calculate everything for each period and just keep that. Then you can save the full data only on certain event.I hope that helps

author: JoHr
author_rank: Regular Contributor
timestamp: January 12, 2023, 09:22:13 pm
content: Quote from: Hawaka on January 12, 2023, 09:16:48 pmExactly around 1GSample on an analog sample feequency of 10kHz.Second based data is sufficient. Interupts or runt will be worth to log those periods in detail. But I can decide this later on.For the quickshot on logging harmonics which I did last christmas minute based logging was sufficient.Additional comment ...I took a look into my frequency logging. I got really every period with value and timestamp in a compressed json format dumped.It makes ~1MB per hour. Peanuts ...

author: nightfire
author_rank: Frequent Contributor
timestamp: January 12, 2023, 09:30:30 pm
content: For stationary use, I had at my last employer Power Measurement (now Schneider) ION7600 and 7650 devices including ION Enterprise oin the software side- nice stuff, if you have the €$$$...Otherwise: Whats of interest is also the earth leakage current in a big building. Some big devices have an own input for a current transformer, others are at least able (Janitza IIRC) to do some differential measurement approach across the phases.

author: JoHr
author_rank: Regular Contributor
timestamp: January 12, 2023, 09:49:08 pm
content: The EN50160 is a good hint.I´ve just had the EN61000 3-2 A/B/C/D in my mind.But that includes voltage and current relations in absolute values and harmonics. I don´t want my own current consumption being mesured.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 13, 2023, 02:38:29 am
content: Have you considered using a sound card and attenuators? The easiest would be to use small mains transformers at well below their rated voltage (e.g. 240V transformer on 120V mains) so they stay reasonably linear, voltage dividers with HV rated resistors can also work if you know how to safely design them.

author: JoHr
author_rank: Regular Contributor
timestamp: January 15, 2023, 12:01:29 am
content: Sure, I did.I have checked 2audio transformers. Separation of primary and secondary side and so on...Both of em did their job. But i decided not to use it because I´d like to measure DC from L to ground as well.From acquisition perspective I´am done. Its more about winning information from the data stream yet.