Hi, I'm new to the forum and recently became involved in energy monitoring in the home which led me to OpenEnergyMonitor. Briefly, I use Demopad, an iOS app, that is extremely flexible in its uses. I currently use it to control av (amp, tv, sky box, Raspberry Pi running XBMC for music), security cams via an axis M7014 and lightwaverf for lighting and monitoring electricity usage. The trouble is, the lightwaverf energy monitoring is fairly limited and monitors total electricity use, ie connected to the house feed. I kind of stumbled into looking more in depth into energy monitoring by a quite unrelated experiment..... I wanted to get real-time feedback on Demopad for the tv power status but its a few years old now and not a Smart TV that would probably be easier to sus out. Anyway, I use a Global Cache iTach WIFI2IR to send commands from Demopad to IR equipment and I found that the (3) 3.5mm connections can be used for sensor inputs and I ended up buying a SCT-013-030 current sensor because of the voltage output - the iTach inputs can take up to 5v. I tried this out today, using a double patress box with blank lid to house the SCT-013-030 once I'd bared the wiring and passed the live wire through it, cabling has a plug on one side and an extension socket on the other. Rather than risk blowing up the iTach, I bought a multimeter and checked the voltage output plugging various appliances in. The only voltage I could register was about 0.008v with a kettle plugged-in. I dismantled and wrapped the live wire 6 times through the SCT-013-030 and this time got 0.8v. Trouble is, whenever I try anything else; lamp or tv, it barely registers 0.001v. Am I doing something stupid or do I need a current sensor say 0 - 10A with a 5v output? I'm now going to look at building an emon kit but I'd also like to get this worked-out.
Your help would be much appreciated and my wife will be happier that I'm seeking advice rather than risking blowing myself or the electrics up, or both! :)
Cheers
Chris
Re: SCT-013-030 or alternative?
Hello Chris, welcome.
There's either something wrong with your SCT-013-030, with your multimeter or with your connections. You should see 333 mV from a kettle drawing 10 A.
Points to check:
Is your multimeter on the a.c. voltage range? Leads in the correct sockets? Is it fused?
Have you passed only one core (line or neutral) through the c.t.? [You did ask about something stupid ;-) ]
Are you connecting to the c.t. secondary coil - have you checked the connections on the resistance range? You should see about 40 Ω (that's about 100 Ω secondary in parallel with the internal burden of about 70 Ω) measured tip - sleeve. The c.t. cable is twin screened, the screen may or may not be connected at the plug, it shouldn't be connected in the c.t., the two inners are the secondary.
Failing that, open up the c.t. and check the soldering - reports say it can be dodgy. (It's easy if you have 3 hands - two plastic clips hold the bobbin down - push those back and push up on the cable - it's quite non-destructive.) Check that the screen isn't shorting, that's been known.