I have searched the site/wiki/forums and have not found much information regarding running this system in the US. Is anyone doing this? Are you able to monitor voltage and current? If so, what AC to AC adaptor is being used?
Another thing I am confused about, is an Arduino unit required for this project or can a Raspberry Pi be used in its place?
Thanks in advance, great system you have here!
Re: OEM in the United States?
I tried to answer a similar question just days ago: North America 120 Volt Power but bear in mind I've not seen much feedback from users in the USA. Hopefully one of them might read this and chip in.
The emonTx as it stands can measure one voltage and 3 currents. It should be possible with a little external circuitry to read another voltage and another current at least. If you are prepared to change one resistor, pretty much any adapter with an ac output will work, but one that shows the lowest waveform distortion and phase angle shift will give you the most accurate results. (And before you ask, I've not measured any 120 V ones, so I have no opinion on this).
If you want to send readings to a database to log, then you need an emonBase, which can be a Nanode or a Raspberry Pi (both getting the data by radio). If you just want to display the data with the emonGLCD, you don't need a Base.
Re: OEM in the United States?
Interesting question and answer, but only because I am using a lower voltage measurement here in the UK, so similar to what you should get in the US.
We have a doorbell transformer in our consumer unit (not connected) that has a 4 and 8 volt output. Being a transformer, should be pretty clean waveform though not measured yet.
The point is I am reading the "4" volt output as the emonTx voltage input. All I did was multiply with a fudge factor until the reading was about the same for the whole hose efergy monitor. Not yet accurate, but good enough to test with.
In short, your US setup should be fine, though depending on your source for voltage measurement may need to adjust theat fudge factor! (ie if you a 110V to 9V trafo you should get a proper power measurement as long as you apply that fudge factor!)
Re: OEM in the United States?
Escapeman
You might like to read up about Voltage Adapters here, and there's no "fudge" necessary, you can learn how to calculate the calibration coefficients here.
You might find, if you check the output of your bell transformer, that the output suffers from amplitude and phase distortion. This means that although you have adjusted the calibration to be correct at one particular value of voltage and current, it may not be correct at other values.
Re: OEM in the United States?
Sorry, just being a newbie, (and I was wrong too - even with fudge factor-applied-correction-for-US, but I'll drop that)
Also, I am very new to all this ARDUINO/C++ stuff, already getting really useful data even before doing any calibrations, data analysis etc, I want to encourage anyone to get started, as I have. Get your hands dirty - it is HUGE fun if a little daunting starting out.
The bell transformer was available at the time, and *should* be clean, but not measured (need an oscilloscope - another project!). Data is still good enough for now, and may be longer term.
If I have a criticism, it is that there is too much info here to Read, Study and Inwardly Digest easily. But I am working on that too.
Re: OEM in the United States?
(Just seen that you refer to the Osilloscope tool I was looking at too!)
Re: OEM in the United States?
Escapeman: We have a doorbell transformer in our consumer unit (not connected) that has a 4 and 8 volt output. Being a transformer, should be pretty clean waveform though not measured yet.
The point is I am reading the "4" volt output as the emonTx voltage input. All I did was multiply with a fudge factor until the reading was about the same for the whole hose efergy monitor. Not yet accurate, but good enough to test with.
That sounds fine to me. There's nothing magic about an adaptor that plugs into the wall. Its AC output is much the same as from any another transformer. I've tried various adaptors and transformers, and although their output waveforms do differ slightly, their difference in performance (for determining real power) seems negligable.
Far more important is to get the reduced size voltage signal to be properly scaled, i.e. centred near the mid-point of the ADC's input range, and spanning most of that range.
If I have a criticism, it is that there is too much info here to Read, Study and Inwardly Digest easily. But I am working on that too.
So are others. All being well, the Building Blocks section will very soon contain a comprehensive guide to all of this material :)