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Welcome Joe Bamberg, Lead Hardware Engineer at Sense
- Joe went to school at Miami, studying for pre-med.
- After a masters degree in EE, he ended up at Analog Devices (ADI) working on Energy metering ICs.
- Lyric labs
- Most meters are electromechanical, using moving parts to measure current via the Right Hand Rule. This then turns a wheel which measures “impulses per kwh”
- Past guest Larry Sears worked connected (gas!) meters.
- The first meters that weren’t manually read used IR.
- Different generations of smart meters moved from measuring active power (Watt hour meter) to reactive power (VAR / apparent power / power factor / Line sag)
- Most homes have a power factor of 1 because of the primarily resistive loads.
- The onboard “filter based metering” used Hilbert filtering (transforms)
- Measuring current
- Joe worked on parts like:
- After ADI he ended up at Qualcomm / Pixtronics working on MEMS display technology. It used an IGZO (indium gallium zinc oxide) process
- The Sense is primarily in the US and Canada right now, measuring split phase, 120V power.
- Founder Mike Phillips has lots of experience with speech recognition (and disaggregation), which translated to the signal processing on Sense.
- Chris asked about if Sense shuts down, Joe later updated that this was addressed on the Sense blog.
- Internally there is a front end, isolated flyback, iMX7 and WiFi. It runs a custom distro of Linux.
- It’s not just for monitoring power, it also monitors events. For instance, one of Joe’s co-workers got a message “Your sump pump is kicking on”
- The solar version ships another set of CTs
- Edge processing (computing)
- There are a bunch of regulations NEC, UL, FCC, CE, CISPR
- Bolt helped with the initial mechanical design.
- It’s small because of the variable size of installation cavities.
- Have more questions? Find Joe on Twitter as @thejoebamberg
I was sampling voltage and current to calculate rms power for a submetering application for Southern California Edison in 1994. At the time there already existed Metricom power meters that measured and transmitted back to HQ using a spread sprectrum powerline and rf communication system developed in part by Metricom.
The network we used for sending meter data predated Ricochet which was also created by Metricom.
https://en.m.wikipedia.org/wiki/Ricochet_(Internet_service)
Also, it was not that Edison didn’t want to develop the system further, but the PUC (Public Utility Commission) didn’t want Edison spending too much money on digital meters when the mechanical ones were so cheep.
One of the things we talked about on the show was filter-based energy meter design and using a Hilbert filter to calculate reactive power (VAR). This white paper from NXP gives a great description of both! https://www.nxp.com/docs/en/application-note/AN4265.pdf#page=15
These meters existed back in the early 90’s too, but I don’t recall the name of the company that Edison was working with that had developed them.
Perhaps just a fan of data, but I love these kinds of devices! I’ve used the Kill-A-Watt and Belkin’s Conserve Insight on many appliances.
But I’ve had bad luck with the whole-house monitoring systems… first I got the Black and Decker EM100B but found that it didn’t work with my (old) meter.. then I got the BlueLine Innovations 28000, and that worked fine until it was removed by SCE a couple months later in order to install their “Smart Connect”.
Perhaps the Smart Connect will someday do the things the Sense can do (i.e. emailing when the garage door opens!), but for now, $300 is a big gamble that Sense won’t join the long list of IOT/Cloud based companies that have come and gone.
Chris, just fyi: I have just had a banner pop up in my browser ranting about ‘net neutrality’ and how I can support the cause (total bull crap I’d never get behind). I know you and Dave didn’t put it there so it must be your Web hosting company. This is happening to a lot of reputable websites and it might be driving people away from your podcast too. Anyway, I’m off to listen to the podcast! 🙂 Merry Christmas.
Nope, that was me! Merry Christmas!
Homes in the US are powered from a single phase, center-tapped secondary transformer that could be called 240 VCT. It is sometimes referred to as 2 phase.
Real Power in watts is equal to the voltage (RMS) times the current (RMS) times the cosine of the phase angle difference between the voltage and current. In resistive load, the phase shift is 0 and the waveforms are sinusoidal. With reactive loads there is phase shift and with non-linear loads (i.e. SMPS) the current waveform becomes non-sinusoidal.