Ive just complete a project to log 3 phase current loads to an SD card, using a Current Cost meter and an arduino mini pro. I initially looked at posting the XML data to pachube but soon realized that all the fine detail would be lost with the low update rate. I decided to store the data on an SD card inside the current cost meter. I now have 6 sec data resolution - low cost - 3phase data logger - and with the addition of an optional LCD showing the real time load on each phase.
Ive posted the code on the next entry.
The logger consist of a current cost meter with 3 clamps, mini pro arduino board,
an SD card, a DS1307 real time clock card, and an optional 16x2 LCD module. The small size of the parts means it can all fit inside the existing current cost meter case (apart from the 16x2 LCD), and if you choice to go without the LCD it can all be powered from the existing Current Cost power supply*.
In the processes Ive learned how to do some basic C programming, and experimented with various arduino boards.... all good fun.
*see note on DS1307 low voltage shut down
data from Current Cost via RJ45 is the "brown" wire, ground in on the "blue" wire, the orange wire at the bottom is heading to the Arduino pin 3.
PS
ReplyDeleteThe DS1307 RTC stops serving data when the supply drops below 1.25 x Vbatt, so about 4v. The existing CC power supply should supply 4.6v, but not all examples might give the higher voltage - if you get data logged but a time stamp of "2000/0/0 0:0:0" try raising the supply voltage.
Some notes on the accuracy of the CC128 unit, sometimes knows as the 144 bug.....
ReplyDeleteThe TX sensor has a range changing feature - to allow greater resolution at low current levels, and one of these switching points occurs when one of the clamps rises above 3Kw. The result is that if one of the 3 clamps goes above 3Kw, the remaining two will register a minimum of 144watts.
There are more aspects to the 144 bug. For example, if you have a steady 1240W load on channel 2, and channel 1 then goes higher than about 2500W, the channel 2 reading will drop by about 300W (i.e. under-read).
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