SafetyNET p® and PSS 4000 as the basis for remote control and protection of rail networks

Railway systems can be compared with distributed production plants in industry: As an operator the aim is to incorporate even remote plant sections simply into an integrated overall concept and to monitor and control the process from a central control centre, without an immense amount of cabling work. The real-time Ethernet SafetyNET p operates in conjunction with the automation system PSS 4000 from Pilz to perform holistic control and safety tasks in the rail traffic sector. The system has the necessary CENELEC approvals and is even SIL 4-capable for the overall application.

A remote control solution INIS-TC developed by Intelis SA, based in Bussigny-près-Lausanne, is responsible for seamless, optimized and safe rail transport on this long line. The Swiss Federal office of transport (FOT) has issued the necessary operating permit. The heart of the remote control solution is the real-time ethernet SafetyNET p in conjunction with the Pilz automation system PSS 4000 for standard and safety functions. SafetyNET p connects the subsystems over long distances and via various media. It provides the benefits of a decentralized control structure without the complexity that
is normally associated with such a system.

In detail, the PSS 4000 consists of multiple hardware and software components such as the decentralized I/o system PSSuniversal, as well as SafetyNET p with its corresponding network components. Other control systems and I/o units can also be connected in a decentralized structure. One of the characteristics of modules with an -R (Railway) in the product name is a particularly robust design. The overall solution meets increased safety and environmental requirements up to SIL 4 of CENELEC en 5012x. Economical solutions are needed at all levels in order to achieve long-term competitiveness with an attractive transport and service offering. This applies to rail operating technology too, of course: appropriate operation and control concepts must optimize procedures and traffic flow, as well as providing maximum safety. The latter is especially important where risks typically arise; such as on level crossings for example. This is a particular challenge, not least due to the long distances involved.

Modern control technology is the future
Even today, classic relay technology with positive guided contacts is often used in railway and signaling technology. But here too, the established trend during modernization work, wherever possible, is to replace cable-intensive hardware that is susceptible to wear with powerful software and hardware, in conjunction with an easy-to-manage network.

Safe data transfer
Today, 17 stations are equipped with the safe, programmable control unit PSSuniversal, which has an integrated interface to the signal box. This sends information to the communication server as well as to the programmable safety systems via SafetyNET p. It is here especially that the modularity of the components proved to be a particular advantage; inputs and outputs could be configured as required in standard and failsafe mode, without extensive cabling work. The SafetyNET p network is a closed loop; one fibre-optic cable across the whole line connects all the communicating components. Today, rail dispatchers can monitor and control all rail traffic on the line safely and reliably from two central control stations in Montreux and Zweisimmen. They receive standard as well as safety-critical feedback, which displays the status of the rail traffic and the signal boxes without interference and in real-time. If necessary, the rail dispatchers can actively control rail traffic or take appropriate measures in the event of a fault.

Data exchange is via SafetyNET p, which is TÜV-approved to SIL 3. If a fault should occur anywhere on the loop, data exchange is still guaranteed through intelligent switches. Corresponding operator panels are used to visualize the information and operating statuses, to graphically represent the stations and to display alarm and event messages. Actual safety stays at the scene of the event: it is always the respective PSSuniversal head modules on-site that check whether a half barrier is closed or a track section is actually free, for example.

The funicular in Les Avants, which links into the railway track, will shortly be integrated into the existing INIS-TC remote control system, which is already operating successfully.