That's true. Simple is always nice.
Those are what I brought up on, and I probably still have a few slugged PO relays in the cellar (although I certainly wouldn't use them to switch 230V). However, I'm not sure that it is possible to get just 'slow operate' functionality with a slug, is it? - 'slow release' or 'slow operate AND release' are easy (according to which end one puts the slug), but I'm not sure that just slow operate is possible. I'll have to think about that - and whether 'slow operate and release' would be OK for my application - as well, of course, as ascertaining whether slugged relays (not ancient PO ones!) are currently 'readily available'.
That might prove difficult to find - certainly on an 'ongoing availability' basis.
Same here (although, in my case, my parents probably didn't even know!). Using a 12V control circuit would, of course, necessitate having two 12V PSUs, one powered by each phase, which would further complicate matters (and would move us a bit further from KISS, since there would, again, be more things to go wrong - albeit probably in a 'failsafe' sense).
My brain is working slowly today. If I wanted to use slugged relays (even if they are still made), I would be stuck with having to use (probably two) DC PSUs, anyway.
Something else to go wrong (this time 'flat'), although again probably fail-safe. However, I think the number of relays/contactors may be escalating - we need at least one with a 230V AC coil (unless we introduce more things to go wrong) to sense the presence of power, one with a DC coil to be slugged (if we can find such a relay), and at least one or two relays/contactors to effect the actual changeover.
Yuk
Possibly in the OP.s case, but not mine. In my case I simply have just two phases of the same 3-phase installation, which has only one earth.
Again, that would only be applicable in the OP's case (my load is not a fridge). An animal such as you postulate could well be impossible to buy off the shelf, hence potentially very expensive. I also wonder if one might have problems of 'hunting' between the two refigeration circuits - presumably one would have to have two thermostats set at appreciably different temperatures.
Most professional electrical wholesalers, or RS Components.
OK, here’s the present arrangement I have for MY application (not the OP’s) for switching a small load to an alternative phase (of a single 3-phase supply) in the event of failure of the usual phase:
I imagine that it's asking far too much to even hope that no-one will find any fault with it 
Well, firstly, in my application, it's two phases of a single supply, hence only one earth, hence no need to switch the E (hence my C/O relay only needs to be DP). If it were two totally different supplies, maybe with different earths, (as may be the case for the OP), then one would do do something about the earthing - but would have to think very carefully about the safety and compliance of switching the earth per your proposal.
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
