I recently bought a RFM12Pi, emonTx V3 and three of the clip on current sensors, but am having trouble getting sensible measurements. I've followed the guide on how to setup a oem gateway:
http://emoncms.org/site/docs/raspberrypigateway
and that all went fine. I receive data from the emonTx when it is on and the data also appears on the emoncms website.
But when testing the sensors etc the values don't seem to make any sense. To test I clipped the sensor(s) around the lead of an electric kettle. When the kettle is off some of the sensors send values of around 4-6, but when I turn it on (2000W) the values are still around 4-6. Furthermore, some of the inputs don't seem to send any data (other than 0) at all. CT1 and CT4 for example are (most often) 0.
I tried resetting the emonTx a couple of times. When I reset it the light will blink red a couple of times and then go off. I assume this is the intended behaviour?
Anyone any idea what might be wrong? Maybe I missed a step?
Re: Problem getting sensors to work
Putting the CT's around a normal kettle lead will not result in a reading. you are effectively measuring the flow of energy at 2 points, once on route to the kettle and again returning. so one reading of 2000w and another of -2000w in the same CT will cancel each other out and equal 0 (plus or minus a little noise etc).
The CT's must only be clipped around one conductor (wire) it can be on either line or neutral but not both.
Check CT1 & CT4 are pushed fully home in the sockets, the most common cause of CT's not working is where they are not 100% home despite looking and feeling like they are. the sockets are very tight.
Paul
Re: Problem getting sensors to work
Thanks for your reply. I guess that means I will have to cut open the wires to get the CT around one conductor? I am pretty sure only one wire is going into my fuse box.
Re: Problem getting sensors to work
"I am pretty sure only one wire is going into my fuse box."
I'm pretty sure that is not the case. Only the LINE conductor is fused, but inside the fuse box you will find the neutral bar where all the second (NEUTRAL) wires connect at a common point to complete the circuit back to the supply, and an EARTH bar where all the circuit protective earths similarly connect to your main earth terminal.
Re: Problem getting sensors to work
Thanks for the help. I had to open up the fuse box and was able to connect the sensor there. It seems to be working fine now.