Hi!
When you have got positive numbers only, then first take the logarithm, because
whatever calculation you make you never want negative values. Next multiply by
100 because the accuracy of the measurements is around 1 percent. Next round to
integer values because the fractional part is uninteresting.
([:<.[:100&*^.)
Then make a discrete fourier transform to get a power spectrum. Low frequency
peaks tell the base load. High frequency peaks tell how often the air
conditioner turns on.
Good luck!
Bo.
Den 7:20 fredag den 26. august 2016 skrev dhkelly <[email protected]>:
I would suggest that you could get away with samples taken at longer
intervals. You won't lose useful information as none of the major
appliances including the air conditioner should draw a startup peak
power for over 6 seconds and what you really need is the increase in
load over a longer time. In addition, the air conditioner is a motor
load which has a lower power factor than something dominated by a heater
element.
A change between two readings at the interval you are using or an
interval of the order of 60 seconds (or longer) will essentially give
the same information -something changed in the interval- whatever it
is. Determining whatever is a bit more iffy. If you get large jumps at
2AM- blame the air conditioner. If at 8AM it could be stove and/or water
heater (breakfast and shower) indicating that you got up then.
The trouble with a whole house monitor, is that a measure of changes in
power alone, may not really give you all the data to distinguish
sources. Another is that a high sampling rate may give variations that
are really not of interest. I think that a step would be to correlate
the data with your direct observations of what went on or off - when(
i.e at the time you turned on a major load such as a stove or dryer-
both of which will cycle their power levels "on/off" in the same way
that an air-conditioner does.
(e.g. an oven will turn on until the desired temperature is reached,
then turn off , repeating this cycle to maintain a a given temperature
(+/- a bit) just as an air conditioner or dryer does).
Don Kelly
Does the meter also measure power factor or "vars"?
On 8/25/2016 8:05 PM, Joe Bogner wrote:
> I posted an article that looks at some data I captured using a whole-home
> energy monitor. I also posted the data. I put up a challenge for anyone
> who wants to take a stab at it.
>
> http://code.jsoftware.com/wiki/User:Joe_Bogner/EnergyUsageAnalysis
>
> How often does the air conditioner or clothes dryer turn on?
> How long does it normally run, when did it run the longest?
> Is it possible to determine when I go to bed or wake up?
>
> I'd be interested in any approaches to answering any of these questions or
> other analysis on the data
>
> For example, the air conditioner draws a significant amount of energy. I
> just turned it on and my usage went from 1460-6000 watts.
>
> Looking at the change in prior reading may be a good start
>
> plot (}. reading - (_1 |.!.0 reading))
>
> I have an electric dryer and electric oven.
>
> I hope the data and article is interesting/useful
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