Computing stuff tied to the physical world

New Flukso meter at JeeLabs

In Hardware on Nov 1, 2012 at 00:01

The Flukso is a little open-source box which can read out a couple of CT current clamps and/or pulse counters to provides electricity / gas / water consumption details – via a JSON/REST interface, either locally or on the Flukso site (private or shared, your call):

Flm02a top

The design is based on the Dragino, and includes an ATmega piggy-back board with extra circuitry specifically for reading out current clamps. It’s not every day that you see designs which can actually deal with power outages in such a way that the last readings get saved to EEPROM in the last few milliseconds – as the system is going down! – but that’s exactly what the Flukso does, showing its great attention to detail.

The Flukso meter’s designer, Bart Van Der Meerssche, is also the driving force behind the Electro:camp meetings, so we had some opportunities to chat and dream about the future these past few days. Lots of interesting options and wild ideas floating around. With Linux in the equation, a lot more sophistication becomes feasible.

To have a better test situation, I’ve decided to add a Flukso setup to JeeLabs, which is in fact trivial since it can connect over WiFi. Power consumption is under 3 W:

DSC 4231

I added the three current clamps as follows (consumption only, no PV solar yield for now):

  1. One 50 Amp CT clamp for the RCD-protected groups 1..3
  2. One 50 Amp CT clamp for the non-RCD-protected groups 4..7
  3. One 50 Amp CT clamp for the induction cooker, group 9

The total should match what I’m measuring with my other 2 pulse counters.

The daughterboard is a prototype with on-board RFM12B (software is work-in-progress).

The other news is that the pulse counter wiring has been fixed, so this is now correct:

DSC 4227

That’s an early morning with heavy clouds. Hey, where’s that sun when you need it!

  1. Neat unit. Is it measuring KW or KVA?

    BTW, C.T.’s are a great way to stay mains-isolated and within local wiring codes, but rules apply to the interconnect cable also. Individual wires inside a distribution board need a voltage rating compatible with the board (V peak + a margin). 400-600V would be typical.

    That flat 6core telephone wire needs additional sleeving to reach such a spec.

    • KW or KVA? Hm… I don’t know. One issue with the Flukso is that it has no zero-crossing detection, but there are spare inputs and I do have an AC transformer nearby (for the doorbell), so it could be fixed.

      Thanks for the note on the sleeving. I asked the electrician about my hookup, and he said it “looked ok”. So much for regulations…

  2. Rewired again ? So now there is net yield?

    • Yes – 2 counters for consumption, one for production. The CT’s also measure total consumption, as three different groups.

  3. That 7W background drain for the cooker is curious. Too much for a clock/timer. You did mention induction, so perhaps it is a greedy supply for the quiescent control panel?

    I’ve seen too many fried online supplies to leave potentially heavy consuming appliances on permament “standby” – they are next to impossible to fuse accurately. A standard issue, flush two-pole 60A breaker with red neon indicator is installed nearby.

  4. @martynj, second time we’ve switched our induction cooker off/on because vacation it got broken (electronics burned out). It was a pretty expensive experiment (600 EUR), don’t you think?

  5. @pavel – agreed, though cheaper than a burnt kitchen! A designer that forgets to handle mains dump spikes needs to go back to grad school ;-)

    Designing analog power circuits well is not easy, but it seems that old lessons need relearning. Here is a critique in a related area.

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