Tuesday, September 18, 2012

Wake EMC Beat Me To The Punch

Well, sorta.

My local electric power supplier, Wake Electric Membership Corporation, has changed out our electric meter for a new, highly capable electronic digital meter. You can now, for free, get a rough graph of your hourly, aggregate power utilization:


I say "beat me to the punch" because they got their meter installed before I got my Arduino power measurement device working. So in that sense, they "beat me". If your standard includes "providing power consumption data granular down to the second", then they haven't beat me.

With their system, you can get data down to the hour. You can't get any more detailed than that for free. This is only measured at the feed point for the house. You can't get circuit-by-circuit, since they are only using the meter to measure. They will give you more data if you sign up for their premium service at US$9.99 a month, but they don't say what that "more data" is.

Regardless, this is good stuff and I'm glad to see it. I've been playing with it and figured out already how to lower my electric bill.  I had developed a habit of fluffing clothes in the dryer every morning on "warm", which was costing me far more money than I thought. Exactly the personal benefit I want from measuring electrical power consumption!

This kind of measurement is helpful for gross electrical loads of limited duration. Something that happens at a particular, possibly repeating time will show up on this pretty well.  Very tiny loads are invisible. I can't tell what's going on with something as big as a PC or small as a power brick.

But there are loads shown I don't yet understand: the every-other-hour kilowatt-hour load you can see in the graph. (each of the green blocks that's 1kwh high and separated from each other by 1 hour)  I'm not sure if that's the water heater coming on/cutting off, or if it's the time-weighted aggregate of all the "ghost power loads" that stay on in the house during both day and night. I may not able to determine that from what little data is shown here.

So this data doesn't discourage me from finishing the project of Arduino-based power measurement. It is encouraging because I've already gotten benefit from this (crude) data, showing the power of being able to do granular, real-time data. Being able to measure with the precision and immediacy of an Arduino data collection system will allow me to find more and smaller problems, like maybe if a power brick or PC power supply are going bad.