Help with Feed Setup for combined values

Emoncms
1

Hi, I have a problem trying to setup a feed with values from 4 CT’s added together. I have 4 consumer units all fed from fused feeds in the garage, so I have 4 x 100A CT’s on an emonTX located in the garage and I want to also have a cumulative value for the whole house consumption.

I created these as virtual feeds using sfeed1 + sfeed2 + sfeed3 + sfeed4 and the same with a kWh output, which appear to output the correct values, but as @David_Buzz indicated, you can’t do much further processing on this, in particular, it’s not available to use in the “My Electricity” app.

I then went down the path of logging to an additional feed in the same way that @pb66 described, I had made the mistake of putting it on the first feed which explained why the total value was slightly different to the sum of the 4 CT’s in each pass, I’ve corrected that now to perform this in the last feed and it’s spot on. However, this only works for logging the “Watts” at that time, and the Power to kWh conversion appears incorrect using the +feed method on the inputs. I’ve attached a screenshot showing the two different outputs where you can clearly see the Virtual kWh value is a sum of the 4 individual feeds, yet the input driven one is significantly higher.

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I persevered and thought I had solved the numbers problem…

Instead of trying to re-convert the combined figure to kWh, I’ve taken the approach of resetting the output value to 0 and then summing the existing kWh feeds, this seems to work as expected and matched the virtual figure, meaning I can ditch the virtuals and use the applications and have more flexibility with the feed data. In the feed values on screen, the numbers look good.

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Although this looks correct on the feeds screen, no output values are being shown in the data feed (much like an issue I had in the virtual where I had to use sfeed rather than feed even though I don’t know the difference), unfortunately, sfeed isn’t available in the input configuration…

So now I’m stuck again…

Ultimately I want to take some of my input feeds to a more granular level and am expecting to be able to use the combined values to work my way back up to a total value without having to have sensors in both places, so I really want to get a handle on this…

I did post the above on an existing thread (I have many inputs that I want to sum together into a "combined" input - #13 by gadgetbazza) after someone else had similar problems (but no mention of the issue I have), but the thread is 3 years old, so I suspect it’s out of view for most people so I created a new topic.

Any help appreciated.

Thanks

2

If you, or anybody, clicks ‘Latest’ at the top of the page, the latest posts are listed in descending chronological order.

So there is every probability that your post has been seen, but whoever it is who can help hasn’t yet seen it. The forums have been very quiet for the last few days.

3

I’ve just setup a “Post Process” to do the PowertokWh on the Total CU feed, with a new output that I’ve called PowertokWh2, which has recorded the data in the feed and is available to graph. So this seems to be one option, although it has only plotted data up to yesterday, so not sure if I can use this on the “My Electricity” app just yet.

4

Thanks for the clarification, I wasn’t sure so though I’d be a pain and post again! Sorry.

5

So, the Post Process feed I’ve created is usable in the Apps section which is good. Initially, I wasn’t seeing any data in the cumulative value for today which makes sense as the feed didn’t have anything recorded for today, and I was getting errors when the app started up. But the feed has updated with some values for today now and the app is working. So apart from a small delay in the daily data being updated, looks like this may have solved the problem I had.

Hopefully this will be helpful to others.