Hi
Finally got my emontx and base finished and running using the 1ct sketches to post to emoncms. I know I should be able to work this out, but is there a simple way to slow down the number of samples to, say, once every couple of minutes?
Also I calibrated the tx easily using a plug in meter next to the current clamp/voltage sensor and a load. However now I've hooked up to the main supply I'm getting some very strange PF readings. The nearest mains socket for the voltage sensor is some way away from the current clamp and I suspect this is causing the problem. How close to you need to get the voltage sampling point to the current clamp to ensure accurate readings?
Thanks
Chris
Re: Adjusting sample rate
Hi Chris,
Good work getting your emonTx up and running. The post rate can easily be slowed down by increasing the ammount of time the emonTx sleeps or delays in between readings. See line 140-150 of emonTx singleCT voltage.
Are you using the latest version of the emonTx 1CT voltage example for github? Calibaration was greatly improved with an update last night.
I have never investiagted the effects of plugging in the AC adapter some way from the CT. My inital thoughs are it shouldnt make too much difference. I'll try and look into it.
Re: Adjusting sample rate
Thanks Glyn
I'll give thpost rate change a try. Do I need to make any corresponding changes to the emonbase sketch too?
I was using the version from github from a couple of days ago. The calibration seemed pretty close out of the box so haven't made any changes to the coefficients.
I'll do some more investigating re the strange readings. It was very stable monitoring a resistive load (kettle) on an extension lead modified to enable voltage and current readings. When I tried to monitor the main leads from my supply meter the power factor seemed unusual (0.4) and the power redings were fluctuatiing wildly. The only thing I could think of is that my distribution board is about 10 meters from my meter and therefore the only available socket for the mains adaptor is effectively 20 meters away from the current clamp.
Cheers
Chris
Re: Adjusting sample rate
No changes should be needed to emonBase. The emonBase forwards any data received from emonTx up to emoncms as and when it receives it.
Definitely somthing wrong here. It should make no difference where the AC-AC monitor is plugged in, the waveform should be the same. Start by double checking all the components are soldered in the right place in the emonTx. Component diagram here: http://openenergymonitor.org/emon/node/209
If you using the AC-AC adapter obtained from us then I would highly recomend using the new calibration. In my tests I found significant discrepancy when using the older calibration. Have you got a plug in energy monitor you can test and calibrate the system against?
Re: Adjusting sample rate
Pretty sure I am using the latest calibration - I must have picked up your updates just as you posted them.
I suspect that I've got a bad joint somewhere as all components are in the right place, I did use a plug in meter originally and, as i said, the calibration was pretty much spot on straight away. All I've done since is moved the kit and wired up to the main meter input to the house - so perhaps something has come loose in the move:-(
Anyway, thanks for the advice. I'll go through everything again and try it out later on. Will let you know how it goes.
Chris
Re: Adjusting sample rate
Glyn
I couldn't find anything wrong so set it all up again and its working fine. I'm posting to an account on your demo emoncms site to test it all and all looks good. Awsome result:-)
BTW Is there an easy way to convert the std kwh and kwh day functions in emoncms to just sum positive readings (ie ignore PV generated output being fed back to the grid)??
Cheers
Chris