Hi, i need to do a project where i can measure power consumption and power factor in order to take some actions and to display it. I have none experience working with Arduino or Raspbery Pi.
I would like some advice in this aspects:
-Which devices i can use to accomplish it. I mean what kind of Arduino, if they have analog inputs and with what kind of CT's are they compatible with.
-What can i read in order to have the required knowledge to develop this and the code i need too, if they are programmed in C++, Python, if i can use Matlab, etc.
I would appreciate any help.
Re: Help with Project
What actions do you want to take? Will that be done only in software (e.g. send a message to somewhere) or in hardware (operate one or many relays - how many)?
There are so many permutations available to you that without knowing more about what you wish to accomplish, it is very hard to advise you which might be the best for you.
Re: Help with Project
The action would be to activate a thyristor based capacitor bank in order to enhanced the power factor of a circuit.
Re: Help with Project
I shall mention some of the things that have been reported here in the forums.
Your starting point will be one of the Arduino assemblies. I do not know details of the range, I think your needs are fairly modest so most likely one of the simpler variants will be enough. You can add a serial display on which you can present text, for example power, power factor and whether the capacitor bank is active.
As far as I know, all Arduinos have analogue inputs. You will need two, voltage and current (maybe times 3 if you have a 3-phase supply, so 6 in all), and you'll find examples of the input circuit that you need to build, along with a description, here in Resources. If only one voltage input is needed, you can probably use our emonTx Shield, which you can buy from the on-line shop. Resources, and Building Blocks in particular, contains most if not all of the theory and practical information that you'll need. You'll also find a software library, emonLib, that does all the calculations for you. All the programming is done in C++, there are many examples here to help you.
The sensors feeding your analogue front end will be a voltage isolating transformer to give a safe isolated low voltage - we use ones with 9 V secondaries but any voltage greater than 1.5 V is satisfactory with one resistor changed to suit. Current transformers are rather harder because to fully load the analogue input, about 1.6 V output is required. Our standard is a 100 A split core (see the on-line shop again) but any CT with an adequate VA rating can usually be accommodated. Others are listed on the "North America" page - you may need those as you will have fatter cables given your 110 V supply.
In terms of output, I'd recommend that you drive a triac or power FET (though this depends very much on what your capacitor bank requires) via an opto-isolator. If you look at the energy diverter projects, you can see how it's done there.
And of course you have the forums here where you can ask questions.
Re: Help with Project
Thank You Very Much, i have investigated and effectivly what i need is an arduino, i have read the input circuits here in the page and they are pretty simple.
If i want to do the calculations on my own, could it be very hard??, I was reading about doing it measuring the time of the offset between Voltage and Current. Any Suggerence.
Re: Help with Project
If you wish, you can of course write your own sketch from the beginning. But the easy way will be to use emonLib.
I suggest you design your hardware, the input circuits, and get it working with emonLib. If it does not work, then you know the mistake is in your hardware, or in the way you have used emonLib. If you get the correct results, you will know that the hardware is correct. Then you can write your own sketch, and you know that any mistake is only in your sketch.
"I was reading about doing it measuring the time of the offset between Voltage and Current"
Ideally, you would measure the voltage and the current at the same instant. Unfortunately, many of the Arduino versions have only one analogue to digital converter, so you must measure voltage and current alternately. That means that there is always a small time difference between measurements that should have been made at the same instant in time. emonLib tries to remove this error with "phasecal". How it does that is explained in Building Blocks.