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Edimax SP-2101W true RMS or not?

I haven’t been able to find specific information on this subject. I’d like to check some of the appliances in use around our house and ultimately feed their performance metrics to EmonCMS. There are a few of these “smart plugs” on the market, one cheaper model is the Edimax SP-2101W that seems to be popular. So, my question is, does someone definitely know if the mentioned Edimax meter uses true RMS for calculations? Also, how do low current measurements look like? They’re specifying an accuracy of 3% for unity PF. I’m suspecting a lot worse figures below that…

I do not know but here is the US link to their manuals. In the upper right corner you can change the Country.

Discussion of Edimax on this thread, not sure about specifications. Have not tested myself:

Thanks, sadly no relevant info in either the manuals or in that thread. I’ve already read both.

You should try and contact them, this is basic fundamental specification info. I’m very surprised and disappointed that specs like this are not easily available. Maybe try their twitter for a quick reply, they also have a support form. Let us know what you find.

I’ve just contacted them via that form. Let’s see if they answer.

I’ve just received the answer, see below. I expected this kind of answer, now it’s official. The bad news is that I’ve found a few RMS meters but they don’t offer network connectivity. So I didn’t lose the reason to make my own :wink:


Dear Sir,

SP-2101W doesn’t use true RMS to calculate measurements.

Best Regards,

Edimax
Technology Poland
Sp. z o.o.

Robert Michalski
Service Specialist

What do you need to do (as distinct from want to do)?
Back on the old forum, Jörg Becker networked a small energy meter: Simple invasive 3-phase energy monitor | Archived Forum

I want a similar device like the SP-2101W with RMS metering and network connectivity. The page you linked involves integrating a bulky DIN-rail 3-phase meter, that’s not what I want. I don’t have a specific “need”, I just want a meter that’s fairly accurate and has the mentioned 21st century features in this portable, small form factor :slight_smile: I’ll use it to try to find hidden power usage and general, casual metering.

I suspected that, but when you mentioned ‘networking’, and hadn’t specified exactly what you needed, it was worth a shot.

A side note: the Belkin Wemo Insight seems to be true RMS, according to this Hackaday post. Good to know, though it costs almost twice than the Edimax meter.