Re: [rrd-users] Modifying results for GPRINT output

Alex,

On 2 Sep 2007, at 13:12, Alex van den Bogaerdt wrote:

> The way you set it up means that the database stores ticks per second,
> not kWh or similar.

Yes.

> Suppose you see 60 of such ticks in a minute, that's 1 tick per
> second, thus 1.25W/s. This is what RRDtool should display. This
> means you should multiply by 1.25, not by 1250.
>
> If you only see one such tick per minute, that's 1/60 tick per second,
> thus 1/60 * 1.25 = 1.25/60 = 0.0208333... = 20.8333... mW/s.
>
> Seeing "m" for milli isn't bad, it's expected. That's because you
> look per second, not per hour. Try multiplying by 3600.

Ah... hmm.... OK have tried multiplying by 3600, and here's what I'm
getting:

http://www.biased.org/misc/tech_probs/leccyday.png

Looks a bit high to me now? Though the tumble drying figure (first
spike) looks more correct at nearly 3kWh. But now I'm seeing "k"
which I doubt is 3,000kWh. Should I be using Wh instead of kWh? I
need to make 100% sure, as it's basically saying I'm using 500 watts
continuously on average. Which is a lot! :(

> Sidenote: Watt is already something per second (Joule per second).
> What you are probably measuring is kWh, not kW. See wikipedia.

Yup you're right, it's kWh not kW. My bad.

> I am also monitoring this usage. Unfortunately I have to do so by
> hand, as of yet I have not found a way to interface this :-(

Yeah, me too, until the law required my electricity company to
replace my old meter which had a disc - the new one has no disc, but
has a flashing light instead for some reason. So my friend was able
to make a sensor to allow my server to record the flashes.

Thanks very much for your time!

Regards - Piers


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