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neb

neb

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#268155 2-Mar-2020 16:45
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Several houses in our street just got hit by power problems due to a faulty neutral connection in front of one of the houses. This could have gone on for awhile were it not for the presence of techies to do preliminary diagnosis and a quick response from Vector, who responded to a late-Sunday callout and came and fixed it (that was pretty impressive!).

 

 

The fault was actually quite odd, it affected a third of the houses but not every third house as you'd expect, this is a short cul-de-sac so it looks like they put groups of four houses, of a total of 11, on the same phase rather than the usual every-third-house arrangement.

 

 

Anyway, thinking about this, I was wondering if anyone knows of any Internet- connected power quality monitoring gear that isn't professional-grade and therefore costs $1K and up. The closest I could find was the ACScout, but the standard USB-connected one has no online manual to see whether it could be hooked up to something like an ODroid, and the (pricey) networked ones are 110V only.

 

 

I just want voltage and frequency monitoring which will catch most things, the ACScout will alarm on over/under voltage and frequency, but that's only the non-usable net-connected ones which are 110V/60Hz. There's various plans around for using AC transformers to sample the mains signal, but I'd prefer a pre-built one rather than an ongoing science project.

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richms
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  #2431469 2-Mar-2020 22:17
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Most UPSs have this in them, available over USB or on fancy ones ethernet.

 

Edit:

 

I also ordered one of these - https://www.aliexpress.com/item/4000259660430.html - the 10 amp one. Am yet to hook it up or read thru the page of how to use it that came with it. I could take it to curry on Thursday if you want to have a play with it?





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neb

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  #2431956 3-Mar-2020 15:49
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Ah, good to know, thanks! Actually if you've played with it all I'd need is info on whether it'll run without the CT added, since all I care about is voltage and frequency.

 

 

In addition from a closer look at the bare-metal version there's no way I'm connecting that to any computing device without a not-made-in-China USB isolator in between, it looks like a standard Chinese-electronics capacitor power supply with no safety or protection, totally wrong components, e.g. cheap generic metallized polyester film capacitor instead of the required X/Y-rated one, I assume the bridge is buried under the capacitor to allow it to overheat, etc. So it's dual function, a power quality monitor combined with a random-delay USB killer, and possible incendiary device.

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  #2431960 3-Mar-2020 15:55
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NUT can talk to a whole bunch of UPS's....

 

https://networkupstools.org/stable-hcl.html

 

Edit: But, now that I think about it, maybe not pull the info you want...




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  #2431963 3-Mar-2020 16:00
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chevrolux:

Edit: But, now that I think about it, maybe not pull the info you want...

 

 

Yeah, that's the problem, at most some UPSes will give things like undervolt info, but not much more. Even then, in some cases it's just "alarm condition triggered" rather than raw data in what the problem was. @richms solution looks like exactly what I'm after, I just need a safe-to-use version.

 

 

For people interested in more info, the magic search term is "PZEM 004", e.g. this site on interfacing it to an Arduino.

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  #2432151 3-Mar-2020 21:49
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I'm using an Eaton 5P UPS, NUT and Home Assistant to do this. I'm also monitoring my EVSE which gives quite different but much less granular readings.

 

Would love to see some actual professional readings, but we sit at 49.9Hz and 235 - 245v most of the time and I'm happy with that.

 

 

 

Click to see full size





I work for a global Data Protection Software company - But my opinions are my own.


neb

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  #2432189 4-Mar-2020 00:22
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neb: In addition from a closer look at the bare-metal version there's no way I'm connecting that to any computing device without a not-made-in-China USB isolator in between, it looks like a standard Chinese-electronics capacitor power supply with no safety or protection, totally wrong components, e.g. cheap generic metallized polyester film capacitor instead of the required X/Y-rated one, I assume the bridge is buried under the capacitor to allow it to overheat, etc. So it's dual function, a power quality monitor combined with a random-delay USB killer, and possible incendiary device.

 

 

Just saw this video on it, which describes it as "terrifying", "a trash fire", "pretty horrifying", and "very unsafe". Definitely not plugging it into anything without a good isolator.

 
 
 

Move to New Zealand's best fibre broadband service (affiliate link). Free setup code: R587125ERQ6VE. Note that to use Quic Broadband you must be comfortable with configuring your own router.
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  #2432190 4-Mar-2020 00:31
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The new rev with more measurements has a slot under the optos and nothing passing that point, so IMO are fine on that front. Not sure what one I have got because its made it into the box of future projects along with about 40 other things.





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  #2432191 4-Mar-2020 00:53
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Yeah, I think that's the 004T model, a.k.a. v3 release. It's main change seems to be "slightly less likely to kill you", which is always a good thing in a mains-powered device.

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  #2432531 4-Mar-2020 15:05
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So my final solution is to use a PZEM 016, which the OpenEnergyMonitor thread discusses in great detail, it's a somewhat less unsafe version of the 004T, for example it uses a SMPS with inappropriately-rated components rather than a capacitor dropper with inappropriately-rated components. The trick in this case is to use an isolated RS485 to USB converter to read the data, specifically this one, which I know is good because a one-star review on Amazon said that when they hit it with a 15kV ESD test the data was garbled. If it can handle 15kV then a potential 240V from the PZEM should be fine.

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