Help! emonCMS feeds

Emoncms Installation
1

Is there a good emonCMS tutorial on how to combine feeds?

I have a 3 phase system, I currently have 3 phase feeds and 3 voltage feeds, one for each phase. I’d like to combine the 3 phases to give me a single power consumption/generation figure.

I’ve seen in the “solar PV” pre defined feed example of power1 plus power2, but I can’t find and info as to how I can make my own feed with for example “power1+power2+power3”.

I have a bit of a weird system in that I have a 3 phase supply and a 2 phase PV generation. so currently I can tell on an individual phase whether I’m exporting or importing but I like a combined 3 phase view.

Are there any other operators available such as minus, divide, multiply etc?

Thanks

Chris

2

I can’t help you with “Solar PV” because I don’t know anything about how those pre-defined things work, however it’s very easy to combine feeds. It’s done on the Inputs page .

Choose a power input and click on the spanner icon. After you send the power to its feed, is there any more processing that affects the value? (Check the help text for each operation to see what it does.)

If there is another operation, go to the end and add “Reset to original”. (If log to feed - the power - is the last, you don’t need the reset.) This will give you the power that you started with at the top of the list. Now below that, add + feed and choose the second power, and again for the third. Now log to feed (and this is where I’m hazy) and I think you need to choose the feed that you originally had in the preset, or can have power1pluspower2pluspower3 if you prefer.

There might be a timing problem - the powers might come in at different times, giving inconsistent results. That’s the reason for power1pluspower2 in the emonPi - the values are added at the point where it’s guaranteed they apply to the same period.

There are lots. Scroll down the drop-down box and as you click on each, you’ll get a “Help” description of what it does.

3

Thanks Robert, I’ll have a play.

But it sounds like I should add the 3 phase values together before I send to Emonhub, that way I can guarantee the values will be in sync.

Thanks

Chris

4

Ideally, yes. But I couldn’t say anything about that because you didn’t say where the data is originally coming from.