Hi!
I would like to monitor my family's pv plant with 20 inverters, so I thought to use some arduino boards with the ct sensors (15 ct sensors in the arduino mega or 7 in the arduino pro mini ) but I have some doubts if I should use several 9V power supplies or if I can use just one and connect it to each board. Does anyone could help me?
I prefer to use the minimum pieces as possible ;)
Thank you.
Could I use only one 9V power supply for many devices?
Submitted by Guest on Sat, 28/02/2015 - 15:59»
Re: Could I use only one 9V power supply for many devices?
You can use one 9vac adapter for many devices IF they do not take their power from that source. The 9vac adapters are closely matched to the emonTx v3x power requirements and any increase will effect the accuracy of the readings. So if you were to have 1 x 9vac and 1 x 5vdc supply you could power several emonTx's (how many depends on how much power the 5vdc supply compares to your demands). You should still use 1 9vac per phase if not single phase. Using separate dc and ac adapters will be more cost efficient with any 3 or more emonTx's on any one phase.
Paul
Re: Could I use only one 9V power supply for many devices?
Thanks Paul for your quick reply!
I drew this schema to explain the idea:
I put one 5v dc power supply but I know maybe I need more, it depends on the demands. In this case, should I use just a 9v ac power supply or I need anything else? Or maybe in this case I don't need a 9vac but I would like to read accurate measurements.
Re: Could I use only one 9V power supply for many devices?
Markinhos, please do not continue to repost the same thing when your posts are are being held in a moderation queue - Didn't you see the warning message on screen?
Re: Could I use only one 9V power supply for many devices?
I see nothing wrong with you diagram that will work.
The 9vac adapter provides information on phase and voltage that is vital to an accurate reading, which is why you must off load the power demands on to the 5vdc to use it for more than one device.
It's only really viable if using more than 2 devices. running 2 emonTx v3's each from it own 9vac would be (almost) the same as your diagram but without the hassle of splicing the power connections.
Re: Could I use only one 9V power supply for many devices?
I didn't see the warning message and I thought it was some problem with my browser or my inet connection, sorry Paul! (moderator)
And thank you so much Paul, all my doubts were resolved. The inverters of the pv plant are located in a very small cabin in the middle of the countryside, and we've just one wall socket. (we are using the mains only for the air conditioner, because during the summer it's too hot inside). In the picture, the white small cabin is where we have all the inverters.
Another problem is the inet connection and exporting the data. Currently, I've running EmomCMS on a VPS where I've my blog and others, and the idea is to use a script to send the data. For that I can use a 3G USB dongle on a Raspberry Pi.
Thanks!