The topic of today’s blog post is the Duplicated Control System (hot stand-by operation), another basic system redundancy concept.

Please refer to the previous articles about this topic: “Introducing INDUSTRONIC’s Redundancy Concepts” and “INDUSTRONIC’s Redundancy Concepts – Single System with N+1 Components” if you need more background information before reading this post.

The Duplicated Control System consists of an active control unit (the Main Unit) which consists of all components of the central exchange unit (e.g. exchange control board, line cards, digital audio processor (DAP), power supply, etc.) and a second control unit in hot stand-by mode (the Secondary Unit) which is equipped with exactly the same components. Usually both the Main Unit and the Secondary Unit are installed in the same cabinet so that there is only little installation space required.

Both control units are synchronized. In case a component of the Main Unit fails the second control unit is automatically activated. After the failure is eliminated switching back can be carried out manually via software interface or if available via keypress at a service intercom station.

By default all intercom stations, amplifiers, speakers, beacons and F&G contacts are connected to both control units to provide high component availability.

Optionally, INDUSTRONIC can provide additional component protection by integrating the digital audio processor (DAP) and the power supply in N+1 configuration for each control unit.

Compared to the Single System with N+1 Components this redundancy concept ensures higher protection as all components of the central exchange unit are duplicated and not only the most critical components.

In my next blog article you will get to know the A+B System (shared operation) concept.