Hello Peoples.
I'm planning on trying to devise an application for the UNO Arduino board for a home power data use logging with 5 different current measurement CT devices.
Scope of the application is that I want to be able to archive via SD card or external drive all the CSV data points in a 24 hour period of time from these units with a referenced power measurement to accurately get the actual immediate watt usage in the period of time with the time date stamped CSV files. After each 24 hour period the unit will reset for the next day, all the data will be derived from a 240 volt AC power source 3 of the CT units will monitor a single 240 volt device while the remaining 2 CT devices will monitor a 240 volt split phase power source. All devices will be using the same 240 volt AC source so only need one power reference.
Just looking for good reference material and or coding help, I'm not overly proficient in the code compiling area so help here will be of great value if someone has some direction would be greatly appreciated.
Determine the measuring range, in Amps, and search for a current sensor.
Then Google on "Arduino + 'the sensor'". That will give You material for starting. Forum does not create code for You.
On purpose of forum is to help members grow in knowledge, not to produce toys.
Oop's I did not include a range variation,
I'm building a power usage tracking system, the max would be 150 amps or ( 36000 watt's at 240 volt AC)
The UNO has 10 bit AD converters so I should have enough resolution for reasonable sample rates being this is on a 60Hz system,
" I would like to preface this as not a fun gadget / toy, but a definitive instrumentation tool with reliable accuracy and longevity for a total power consumption over the course of time with accuracy down to the watt per second level stored to a large sd card or external hard drive with the ability to pull data of for review without interrupting the archiving system.
That was a heavy load, 150 Amps. Are all the measuring points exposed to such high currents? Small current curcuits will not get much resolution using a 150 amp shunt...
Search first for at least one suitable current transformer to begin your experiments.
Is this single phase ?
Anyway you'll find several example projects in the energy monitoring area in this forum. Interfacing an Arduino to an SD card reader is relatively easy.
A 10bit adc gives 1024 discrete levels. Is that enough for your 36kW installation.?
Take a look here.
If you have an electronic meter at home it may already have a pulse output via a flashing led .
Alternatively , if it’s the rotating disc type then you’ll notice it has a section that is reflective .
Both these make it easy to measure energy consumption by just counting pulses rather than do the harder maths on sine waves
You could alternatively just buy a meter with a pulse output - this is likely to be a nice safe cheap alternative ($30 ish)
If you go with your original thoughts , add a second voltage transformer to power your project
@wildbill should have hyped up his link! That is where you need to start: has everything you need to know about power and energy monitoring, from the electrical fundamentals, current sensing, voltage sensing, etc., and it has a shop where you can purchase monitoring software and hardware. Even if you're not interested in purchasing from them, the site is definitely worth visiting.
https://guide.openenergymonitor.org/applications/home-energy/
Hammy,
Thanks, I do have one of those but I'm measuring 4 different independent units off the same power feed, so I know what, where and how the power is being used. I have done that in the past it works just not to precise.
Railroder,
I have 200 amp CT transformers that give 0-.0333 output prospectively, so with some math I should be able to get down to the level that I need, But I may use an amplifier for better gain control and noise elimination.
Dave,
I have an Eyedro unit currently, but as with all the IOT devices of this nature I'm finding that they are just not precise or dependable enough to keep a decent legger of the goings on. The Eyedro won't acknowledge any thing below 50 watt's. Some of the devices can pull as little a .2 watt's and at 240 volts that can be rather significant.
Do not even think about using shunts with 240VAC supplies.
They are for safety certified, professional installations only, as they offer no isolation whatsoever and are EXTREMELY dangerous for home use.
Drop that idea. Buy current sensors that better fits the measuring range for the low amp sections.
RC filtering... Wait and see what You need.
Yes, but who is listening?
You tell about currents as high as 150 Amp, 36 kilowatt. Why bother that much about 1 or 2 watt? What's the practical use of that data?
But you mentioned CT (normally understood as current transformers ) several times in your first post. These can be non invasive (clamp on). Have you already done some research for suitable devices?
Jremington,
I'm using CT transformers not shunts because of the need for isolation.
Thank's for the warring though.
Agree ….This will be almost impossible - the range is 36000 to 1 , you won’t be able to measure the low end .
If you meter each of your loads , with a conventional meter , then you will really struggle to better that.
Have a look at transformer and A/D specifications.
A10bits A/D gives 1part in1024
resolution
Hammy,
The use of this is to monitor a high current device. The reason I have to concern myself with just a 1 or 2 watt draw is this could be significant safety concern, at those voltages.
250 volts 250ma =1 watt and that is a substantial draw, if it's not going where it should.
