I have just found this Forum and I am very interested in developing an Energy Monitor to control PV and Grid power in an eco house. I have been experimenting with Hall effect clamps and my main problem is detecting which way the power is flowing - i.e. am I exporting or importing.
I see from your display pictures that you have a clear + or - indication of power flow direction.
Having looked through most of the pages of this site (but I have not studied the software) I do not see how the OpenEnergyMonitor Arduino system does it. Does a CT sensor behave differently from a Hall sensor and give a distinct directional output, or do you compute this from voltage/current phase angles via your mains transformer ?
I have been playing with digital and mpu systems for years but am not well versed in 240v phase angle details.
Re: 240v power direction
Hello, nice plans!
There are two ways you can sense direction
1) Using a AC voltage adapter as in the Mains AC v.3 circuit.
2) If your measuring PV output and the house power consumption then we can infer direction:
Import = house - pv output.
When import is negative it is exporting.
All the best
Trystan
Re: 240v power direction
You might like to see my project which acheives your objectives. I used Trystan's No2 because it gives you greater flexibility in the home wiring circuit. (seperating the immersion power circuit from normal power usage to prevent hysteresis).
I also post the readings to Pachube so I can check on generation/usage/efficiency.
Re: 240v power direction
I am new to the open energy monitor,have just started the project with my SCT-013-030.as this kind of CT has the inbulit burden resistor i am not using any burden resistor.
My problem which i am facing is with 100W bulb i am getting ct output of 14mV and i can't give it directly to my atmega 328.any suggestion on how to amplify these 14mV to my controller level.
The other problem is, arduino is not available here can i form my own board with Atmeg 328 and other components.any suggestion Plz!
Re: 240v power direction
Hello faizan
The circuit you need to interface a CT with an atmega 328 can be found here:
http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface
and yes it will work if you build an atmega based board, it does not have to be an arduino.
Re: 240v power direction
Hi Paul,
Your project is exactly what I am also looking for. Do you mind if I ask for the schematic diagram which shows discrete components attached to Arduino circuit.
Thank you very much.
Re: 240v power direction
See "Building Blocks" for the basic theory and the emonTx Shield circuit diagrams on the Wiki for practical circuits.