EmonPi and Smart Meter Readings

Hi there. First post on here.

I’ve just installed my new emonPI energy monitor with CT1 connected, the Ac-Ac adapter and also an optical sensor to my Elster AS300 smart meter. I’ve setup everything as per the guide and all is working well. I’ve set the scale factor for the optical sensor to 0.25 as the Elster is 4000imp/kWh.

I’m running just the Myelectric app for now and I’m noticing that the Watts reading is around 20-30 Watts different to the output shown on my smart meter live display. I’m guessing that this is because the Myelectric app uses the CT reading and not the optical sensor.

Do you think that is correct? If so, is there a way to change the app to use the optical sensor to get the Watts.


Can anyone help?

I can’t answer the straight question - which does Myelectric use, but I can say that it’s possible to tweak the calibration of the analogue inputs in emonhub.conf to get the accumulated Wh to align with the pulse count. I’ve just had the “Calibration” page in ‘Learn’ changed to add the details.

I think you should treat the pulse count as the definitive value and scale the analogue power/energy to match that, don’t try to scale pulses to fit the analogue value.

@X6tus is your optical pulse count logging to a cumulative kWh feed? If you’re running emoncms locally, there is an input processor called ‘kWh to power’ that you could try. The results are not always that good though, as the resolution in the kWh or/and the time usually results in a messy power feed.

I have this issue (monitoring pulses using a Hall effect sensor on a gas meter) and I’m successfully using kWh to power on my EmonPi. However, I want to be able to monitor this historic power feed from the cloud on emoncms.org but the kWh to power conversion doesn’t exist there. Is there another way to convert, or can I read the kWh to power output on my EmonPi direct to emoncms.org?

3 posts were split to a new topic: Measuring Gas with Hall Effect Sensor

@X6tus, did you resolve this issue?

Wow, I never did get back to this post! So I abandoned the optical sensor in the end I’m using the connection for a temperature sensor instead. For power monitoring I’m just using the standard clamp and AC connections.