Alternative redundant PSU sollution

[yoseikan]

Sorry for the English, I find automatic translation awful for native speakers.
Planning my installation I have put the following question to the forum: Is it possible to use standard backup PSU?
https://knx-user-forum.de/forum/%C3%...h-power-supply
I have gone forward with this setup over a year ago and thought this could be of use.
In case any of you want to create such a setup, this really works very well:
2 Meanwell PSC-100B (80€)
2 chokes from Siemens (80€)
2 12v 7aH batteries (40€)
3 swithes 3*2 poles (7 €)
I also have an extra choke for redundancy purposes.

I have an installation with 80 plus devices, divided over two lines, which communicate through a bus coupler
So, one power supply has its output connected to 2 chokes (1 for each line in my home) and it is further used to power my unchoked line (Weatherstation, etc).
It is connected to the batteries (connected in series for 24v)
The other PSU is just waiting for a disaster (but ready to be switched on).
Both PSU are connected to the switches, in a way that only one can be connected at any time.
Switch 1 cuts AC power/turns on power to PSU-A or PSU-B
Switch 2 cuts DC power/turns on power from PSU-A or PSU-B
Switch 3 cuts backup battery/turns on backup for PSU-A or PSU-B
Anyone can disconnect and reconnect or change PSU. No need for me to do that, giving time to arrange for a repair without disrupting the installation.
Power failures have no effect, the KNX BUS goes on working and you may use the binary outputs from the PSU to report AC or battery failures.
Have this system in place for over a year now, without problems.
Hope it helps someone!

Cheers

[yoseikan]

Just a quick update:
In 3 years I never had a PSU failure, so my backup PSU is still unused. Never had problems with the setup and, in case of mains failure (which happened many times), I never have lost the bus. This is a very reliable setup, giving the PSU is the only device in a KNX setup that compromises the whole installation in case of failure.

[xrk]

Have a look at MDT STR-0640.01 - it might be a much simpler redundant KNX power supply solution.

And in case if you need more than 640mA (in another thread you wrote about 80 bus nodes), you can connect two STR-0640.01 in parallel for 1280mA (although sounds funny, this is allowed by the KNX specs and explicitly also by MDT for STR-0640.01).

In my case I have one input of STR-0640.01 connected to mains, the other input is connected to uninterrupted power supply (std. 19" rack device for IT devices). This way I can still perform maintenance on UPS without interrupting KNX. On the other hand, if the mains power should fail, I have signalling over tiny displays in wall push buttons (MDT Glass Push Button II Smart).