Hello all. This subject got touched upon in a different thread about DMX (solved), so I thought it better to start a clean thread.
I have a project that requires an Arduino to monitor up to 5 different AC mains currents (0-16A) and voltages.
The voltages are 110-230v range.
Jremington very kindly pointed me to this resource which is great:
I am an electrical engineer, and fully aware of the dangers of mains AC voltages. I work on fork lift 3 phase chargers alot.... they really will fry your parts if you are not careful!
As usual, this needs to be compact. I am thinking maybe using the current detection method in the link above using CT coils which are readily available.
If we assume worst case of 5x incoming supplies to monitor, then that is 5x Arduino analogue inputs reading 5x CT coils.
My bigger issue is the voltage. I obviously cannot fit 5x AC/AC adapters inside my enclosure.
My thought was to find a very small footprint transformer and build a dedicated AC PCB that housed 5x transformers. But I just cannot find any very small transformers suitable.
That also still takes up a lot of space.
It occurred to me that do I need 5x transformers? I could probably just use one and switch the supplies into it with a Triac (MOC3041?). The load is negligible.
My problem with this is the potential for a Triac failure and therefore accidental mixing of the AC incoming supplies.
You could use 4x small relays to control 5x AC supplies that use DP contacts to provide a logic system to prevent the AC signals ever meeting each other, but then you have relay coils chattering away constantly as it switches to monitor each signal.
Then there are these:
These are ideal, and if I had the room, it would probably pay to simply add these to the project.
But my monitor already has a TFT screen, so it seems pointless adding separate screens for this data.
I imagine (maybe incorrectly) that these Chinese modules sample the AC voltage and current in a less than acceptable way! I cannot find any circuit diagram for such a unit.
I do have a similar version in the garage that displays volts, amps, KW, phase etc. I had a look inside that and its a very complicated little PCB.
Any thoughts gratefully received.