Hi,
I've got an emonTx which is working fine with a single clamp.
However, when I plug in an AC-AC adapter (the one from the store, and the calibration value in the default sketch looks right according to the photos on the wiki) and use the emonTx_CT123_Voltage sketch, I get some really strange values back:
http://f.cl.ly/items/1Q1g2S2v0T1z0B3U0c3u/Screen%20Shot%202013-03-04%20a...
Any ideas?
Thanks,
Ian
Re: AC-AC Adapter
It looks like the first line is the voltage. You just need to divide by 100 as it's transmitted in integer form as volts x 100.
Re: AC-AC Adapter
Yeah, I assumed that - and the bottom one I assume is the usage in watt - but it looks a bit low (current cost and normal emonTx with clamp was showing about 400 odd) and a negative number which I don't get!
Thanks,
Ian
Re: AC-AC Adapter
It will be negative if you have the CT clamp the wrong way round.
Re: AC-AC Adapter
The wrong way round? - how can it go the wrong way round when it just goes round the cable?
I've never had negative numbers before....
Ian
Re: AC-AC Adapter
Take the clip off and turn it 180 degrees and reattach it.
A bit hard to explain, if the cable runs horizontally and you put the clamp down over the cable, take it off and put the clamp on upwards.
I dont understand the technical details but without the AC-AC adaptor the emontx has no way of working out the direction of flow of the electricity, with the AC-AC adaptor it can, therefore with the adaptor ftted you need to make sure the clamp is attached the correct way.
Re: AC-AC Adapter
Ohhhh!
So i've never noticed it before because it doesn't matter normally - but then when you connect the AC-AC adapter, the direction of the clamp suddenly matters?
That makes sense! :)
Thanks,
Ian
Re: AC-AC Adapter
Try reading this: http://openenergymonitor.org/emon/buildingblocks/ac-power-introduction