Logging house voltage
March 12, 2022 11:53 AM   Subscribe

My power company gives me a putative stable 135V. I’m not convinced. I was going to use a DC converter and step-down circuit plugged into an Arduino for long term sampling, but I thought I would see if anyone had a better suggestion first.
posted by Tell Me No Lies to Technology (13 answers total) 1 user marked this as a favorite
 
Some smart outlets have line voltage monitoring. I have several Sonoff S31 in my house, and they have this capability. While I use a replacement firmware ("tasmota") that has expanded logging capabilities among other things, photos of the official tasmota mobile phone app (which I haven't used) show that you can at least check the current voltage, if not a voltage history. Note also that when the internal switch is off, it'll register 0V, so just be aware of that.
posted by the antecedent of that pronoun at 12:15 PM on March 12, 2022


based on the voltage graph near the end the Sonoff S31 voltage monitoring may not be well calibrated, at least when using the Tasmota firmware. However, you should still be able to use it to detect variation even if the voltage number is offset by some amount. (in this case, the person's two devices measured ~15v difference on the same household electrical service)
posted by the antecedent of that pronoun at 12:22 PM on March 12, 2022


This might do what you want. There are a number of similar items on amazon.
posted by H21 at 12:54 PM on March 12, 2022


Assuming you already have some sort of always-on computer, you could get an APC UPS to protect the computer from power problems and set up SNMP logging via PRTG (as suggested there) or some other SNMP logger. As noted in that article the most basic UPS products won't support SNMP, so check the specs before purchase. That article mentions using PowerShell to monitor a basic UPS connected via USB.

We've got a couple hair-trigger UPSes that always beep when our power glitches, but I've never bothered to set up logging because the power utility wouldn't take my word for it anyway.
posted by fedward at 1:02 PM on March 12, 2022


If you want to go the arduino route, you might consider looking at the HCPL3700 or similar (that's just the one I happen to know about) instead of a step-down circuit. (There are also many cheap USB and or bluetooth headless DMMs. I don't have a recommendation.)
posted by eotvos at 1:15 PM on March 12, 2022


There are AC voltage sensor boards available (on Amazon and elsewhere) that ought to do the trick. Given that you're wanting to record samples, you might be better to use a Raspberry Pi Zero, as it doesn't need anything extra to do data logging.
posted by pipeski at 1:25 PM on March 12, 2022


(Sorry - in my comment above, I chose the wrong part! There are analog opto-isolators, which could be connected directly to an analog in on an arduino. But that isn't one of them. It's an adjustable threshold isolator. Oops.)
posted by eotvos at 1:28 PM on March 12, 2022


My go-to part for line voltage monitoring is the Analog Devices ADE7953. I can measure L/N, L/E, and N/E simultaneously.

You can try to find an evaluation board and wire it into your project (be careful with that hot wire!), or find a home automation product that uses the part.

From looking at various github projects, the Shelly line of automation/monitoring products might be worth looking into.
posted by JoeZydeco at 2:30 PM on March 12, 2022 [1 favorite]


You might also have some luck with the ADE9153A. There's an Arduino shield/eval board that can fit right into your project. It's $148 at DigiKey, 33 in stock today.
posted by JoeZydeco at 2:45 PM on March 12, 2022


Sorry, I just have to ask: What part of the world do you live in where 135 V is a proper power company line voltage?
posted by Juffo-Wup at 2:30 PM on March 13, 2022 [1 favorite]


OP might be measuring peak voltage instead of RMS, but that would still be off scale (135/sqrt(2) = 95.4).
posted by JoeZydeco at 7:43 AM on March 14, 2022 [1 favorite]


Response by poster: Thank you for the inspiration everyone. I ended up going with a ZMPT101B, which cost $10 and works nicely with the Arduino. I just kicked off a week long .5 second interval sample.

Sorry, I just have to ask: What part of the world do you live in where 135 V is a proper power company line voltage?

Sorry, my mistake. I’m in Mexico where the proper voltage should be 127 V. Today the Fluke measures 125 V. Two days ago it was 132V. According to the power company there should be a hard limit at 135 V.
posted by Tell Me No Lies at 1:46 PM on March 22, 2022 [1 favorite]


Response by poster: (for those playing along at home it seems to swing between 112V and 140V. Next up is to measure it at the light fixtures, but I think I already have a hint why my bulbs burn out so quickly.)
posted by Tell Me No Lies at 12:36 PM on March 24, 2022


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