Want to Know What's Happening in a Building? Listen in at the Breaker Box | Hacker News Reader

Want to Know What's Happening in a Building? Listen in at the Breaker Box

spectrum.ieee.org

56 pointsteklaperry16 comments

In the Chicago suburbs the local electric utility (ComEd) has been installing smart meters on residences over the last couple of years. I got mine about 18 months ago.

The meter is Zigbee-capable, so I went out and got a utility-approved gateway to read the meter (the meter allows access only to approved MAC addreses) The Rainforest Automation RAVEn cost me about $50 (it might be discontinued now)

http://rainforestautomation.com/wp-content/uploads/2014/02/r...

There are a number of things you can query from the meter, but mainly you can read the current demand every 4 seconds down to about 10 watts resolution (the Verdigris device is claiming 5-Watt resolution). It's all in a tidy XML format with a published API spec.

Long story short, you can play with some of this stuff on your own right now in certain parts of the world.

What was the approval process to get the Raven device whitelisted for access to the meter?

(I own a Condo in Schaumburg)

> “We shrunk the sensors and got high fidelity signals,” Chung says, “by figuring out novel ways to fit more powerful sensors into tight spaces.” Some of that had to do with the arrangement of the magnetic material, he says, but can’t say more until patents are filed.

Which is interesting. I guess the main component here is manufacturing cost, since very small, very high capability probes exist since the ~60s. E.g. Tektronix has had small probes with 50-100 MHz [which is orders of magnitude wider than you'd need for this] bandwidth since then.

It's cost, size, and regulatory. Existing current probes that are magnetically coupled and thus don't require an electrical connection to the mains (which would be a safety/regulatory nightmare) are big: http://www.tek.com/current-probe

A small probe, like the P6021 (which I own [0]) is pretty small. The transformer itself is tiny; there is only a small PCB in the handle with some frequency compensation. (However it is said that these are difficult to manufacture - more so for their Hall-enhanced partners - due to the precisely ground halves of the core).

The bigger probes that are meant to go on bare, live bus bars and such are probably mostly air to give the operator the required safe handling distance... probably not an issue for a clip-on probe that goes on insulated wires?

[0] Technically a P6021 sold to Philips who bundled it up with a matching amplifier of their own design.

That probe is pretty small, but keep in mind that many of these need to be tucked into existing circuit breaker panels while maintaining certain clearances for regulatory reasons. They also need to be easy to install for safety and product adoption reasons.

I think we are saying similar things though. I worked on this project with Verdigris (though I was not personally responsible for the design of these probes) and, to your original point, the challenge is fitting these at a reasonable cost while achieving the desired accuracy. I guess I'm so used to low manufacturing costs being a given that I tend to focus more on the other aspects of the problem.

This sounds a lot like https://sense.com/

There was an episode of This Old House about it: https://www.youtube.com/watch?v=HZft4qoK7Ds

It's very cool, was brought hip to it from TOH.

I've watched a few reviews and videos on it; definitely considering it.

I especially like the diagnostics part of the equation; which is still an algorithm quite in beta.

Beware, their AdSense is strong. It'll follow you forever.

Nice. I would love to see something like this for water too, although Without magnetic signals to sample, I'm not sure how it could be done. My girlfriend had a water bill twice everyone else's in the building and the problem ended up being a toilet that was leaking silently.

Sounds super similar to some of the research out of (The University of Washington UbiComp Lab)[http://ubicomplab.cs.washington.edu/publications/] back in 2010. There was a project led by Shwetak Patel, that ultimately turned into (Zensi)[https://www.crunchbase.com/organization/zensi].

Basic premise was to use some DSP to detect electrical noise emitted via various appliances and extract usage patterns from this. The same approach could then be used for water and gas systems by detecting pressure, rather than voltage fluctuations.

From what I can tell this seems to have now just been consumed into the depths of Belkin.

Amazingly, I can actually speak to this. I'm Ph.D. student in Shwetak Patel's lab, and yes, this looks to be extremely similar to the ElectriSense [1] work done by Sidhant Gupta (now at Microsoft Research).

The water analogue was Eric Larson's Ph.D. work, and was much more difficult from a DSP perspective due to two separate issues:

* When water is flowing without turbulence (laminar flow) it doesn't leave much of a signature on flow or pressure sensors

* Any kind of signature that does exist is often changed significantly depending on the network of pipes that stand between the single point sensor and the source of the water event.

For these two reasons it took a while for us to work out a high enough accuracy for the water stuff (in the end we used a water pressure sensor plugged in close to your water heater as a fairly central point that most people can access easily) and that was published as HydroSense [2]. We like our *Sense names. :P

HydroSense was indeed bought up by Belkin, and they are pushing it forward in a way that we just cannot do in academia, so that's a good thing. ElectriSense I don't remember exactly what the IP status of it is, but I do know at least one student was working on some interesting extensions of it that may be published in the next year.

[1] http://ubicomplab.cs.washington.edu/publications/electrisens... [2] http://ubicomplab.cs.washington.edu/publications/a-longitudi...

We have something similar for water, see dropcountr.com.

But even without that, the water is already metered, and values on the meter are required to be visible and legible, so I'm not sure what the challenge is.

> "They then set about rewriting an algorithm they’d been researching at work, one designed to accelerate packet separation in chips, to apply it to this problem."

IANAL but are they not worried that Broadcom will sue with statements like that?

Eventually the necessary monitoring circuitry will be embedded into every circuit breaker. Of course, there will still be a need for analytics; the raw information from the breaker won't be sufficient.

Uggh. Privacy nightmare.

Ditto that.

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