KNX bus reliability against a short circuit

[hajimomeni]

Dear friends,

Hello.

I need your help on a question we have about the reliability of a knx installation. I am sorry to write in English, but I could not find a good English KNX forum. We want to design a knx network for a large hotel. The owner has concerns about the possibility that knx bus stops working as a result of short circuit. Specifically, suppose we have a key installed outside a room (i.e. accessible by people who pass the corridor) which is connected to knx network. If someone connects the two black and red wires of knx connector in this device, the power supply on the corresponding line segment should stop functioning. Imagine that the situation intentionally continues long enough to outperform the tolerance of power supply circuit. What will happen to bus and the knx system?

I know that the power supplies have circuits to protect the devices against short circuit physically, but I think the knx system is vulnerable and will lose its functions (including security, lighting, etc.). How knx copes with this imaginary scenario?

Are there any knx devices with internal isolation? Like, for example, an optocoupler passing the electrical signal from one device to the other instead of directly connecting wires?

I appreciate any idea or comments thank you.
Mona


P.S.: Again, I am sorry for writing in English in this forum.

[Uwe!]

If someone connects the two black and red wires of knx connector in this device, [...SNIP...] What will happen to bus and the knx system?

The bus or at least the line will stop working as long es black and red are connected and will work as befor whenn connection is disconnected.

No KNX device can work with an short circuit in bus, cause they have the bus as a power supply. Even opto Coupler can't help here.

KNX is NOT made for security devices!

PS:
hope my english is good enough!

[hajimomeni]

Thanks a lot Yeah your English is good.

KNX is NOT made for security devices!

It's disappointing to hear that KNX is vulnerable to such faults. It implies that the designer should always have an emergency replacement for all the automated functions. Maybe not a problem in residential sites, but for hotels, hospitals, and offices it can be a weak point for the knx installation.

Which smart home technology do you know that has a more reliable behavior in case of such threats?

Mona

[Uwe!]

It implies that the designer should always have an emergency replacement for all the automated functions.

Well, KNX devices are normally extremely reliable but nevertheless they can break down. But that can happen with each and every automation technology. Even a simple switch may have a failure. Due to the fact that KNX is NOT centralized, a break down normally applies only to a little part of the system. And replacement can be found easily, not necessarily from the same manufacture.

Which smart home technology do you know that has a more reliable behavior in case of such threats?

I don't know one, but I only know KNX quite good.

[Gast]

Specifically, suppose we have a key installed outside a room (i.e. accessible by people who pass the corridor) which is connected to knx network. If someone connects the two black and red wires of knx connector in this device, the power supply on the corresponding line segment should stop functioning.

If someone wants to trouble you, no KNX is needed. He just needs to trigger the RCD device in public areas.

[gaert]

Just put a low-current-fuse before/after the KNX-Device...