I have a big ducted A/C I’d like to monitor, but unfortunately it is 3-Phase – Although its total maximum rated power is only 8100W. It even has a 20A circuit breaker to the outside unit.
I’m not even sure what I’d like to do is “technically feasible” at all. Can I somehow hack the Aeotec Heavy Duty Switch Gen5 to measure the power consumption of this A/C?
Without knowing where in the wold you are this is meaningless.
8100W/240V = 34A (single phase)
8100W/120V = 68A (single phase)
Keep in mind the power ratings on smart devices are for resistive loads. An A/C unit has a compressor and fan inside. These are not resistive loads and you can see peaks of up to 5x their power rating if it does not have some sort of soft starter.
To monitor the power you could use a “non-contact” method like current transformers. The Shelly EM3 is good for measuring up to 120A per phase (three phases). It also has a 10A relay you could use to control an appropriately sized three phase contractor if you require power control.
Apparently the side of the A/C claims 440VAC with a maximum rated i nput of 8100W – But its not clear to me why it even needs 3-Phase power or how this works out.
As I keep saying, your A/C is not a resistive load. The Aeotec switch power rating is only for a resistive load.
An A/C has a compressor motor and a fan motor these can draw 5 times their rated switch on current if they do not have soft starters.
Do you actually need to control the power to the A/C or do you just want to monitor its power use?
I gave you options for both:
This is a wifi device that can be integrated into home assistant easily with mqtt. No cloud connection required. No Home Assistant Z-wave network initialisation after a restart required.