Railway signaling is used to control railway traffic, to prevent trains from colliding and to adjust distance and the speed for proper braking time and management of tracks. Today, ERTMS/ETCS is the most advanced management, control and protection system of rail traffic and related signaling on board. The future trend will be the introduction of ever greater dynamic systems that require increasingly faster responses, real-time communication and a growing availability of wireless and wired technologies.
Over the next years there will be an increasing number of inhabitants and a flow of people in transit in big cities. At the same time fuel costs will rise. Therefore, it is expected that the number of passenger trains will rise by 70%. To support this increase, the infrastructure needs to develop more capacity and systems need to become faster, embracing an Ethernet and IP architecture able to replace the old networking technologies.
By 2015, most of the incompatible national train control systems will be replaced by a single European Control Train System. This implies a willingness to use standards to unify the infrastructure at a European level and enable the interoperability of the vectors. This leads to reliance on high-tech and high quality products based on recognized international standards - even better if these are guaranteed by IRIS Certification.
There is a need to simplify the processes of activation and to reduce maintenance costs, by decreasing the number of operations in the field, increasing efficiency, ensuring operational safety, with every possible element of risk calculated, and to reduce any service interruptions, a source of huge economic losses for railway companies. This is leading to a renewal of railway networks exclusively based on the highest experience, reliability and flexibility criteria.
Copies of detailed test results as required for certification against external standards are not held on our publically accessible internet site. If you would like to see copies of these test results for a specific reason, please contact either your local Sales Representative, or firstname.lastname@example.org
MRP: 50+. Switches based on ring topology. Recovery time is almost independent of the number of switches in the ring
RSTP: up to 40 Switches for any type of topology. Because RSTP works in a hop-by-hop principle, recovery time will almost linearly increase with the number of switches in the ring.
There is no best or worst case recovery time for HSR, since there is no recovery time at all. The network recovery time from no fault to a single fault in a ring will always be zero. Also, the repair operation from one fault to no fault is also with zero switchover time.
HSR, as MRP or RSTP in ring configuration, can only sustain one fault in the ring network. This is due to the physical topology, not due to the redundancy protocol. Rings that are coupled via Quad Boxes do not share the same redundancy domain. Therefore, each individual ring can sustain a single fault.
Both HSR and PRP are specified in the International Standard IEC 62439-3. HSR and PRP are therefore standardized and not proprietary technologies.
While HSR and PRP are superior to MRP or RSTP in terms of reconfiguration performance, there are also drawbacks to the technology:
Where seamless redundancy is not explicitly needed, the use of MRP (with SubRings) or RSTP technology may be more cost-effective than HSR/PRP. But where the application requirements justify the additional costs, PRP/HSR can be utilized.
There are several answers to this question. It is true that the technology is standardized, but there are several key factors why a customer should buy a Hirschmann HSR/PRP device:
HSR and PRP were conceived for use in IEC 61850 substation automation, where network reconfiguration times cannot be tolerated, especially on the process bus with sampled values traffic. However, PRP/HSR can also be used in factory automation, especially as redundancy solutions for motion control applications.
In short, PRP/HSR can be used anywhere when only very low to zero network recovery times can be tolerated. This is especially true in time synchronized networks, e.g. with IEEE 1588v2. HSR in particular with its ring structure and cut-through switching, can also provide very low end-to-end latency on ring networks.
The total number of HSR devices in one ring should be limited to 50. This is mainly to reduce the latency in the ring. For very time-critical applications it may be necessary to limit the number of devices even to a smaller number. Another limitation for the number of devices in a ring can be the size of the duplicate detection table inside the device. This is dependent on the implementation.
The IEC standard (IEC 62439-3) for HSR and PRP is now stable and the feasibility of the technology has been shown. HSR and PRP are highly future-proof thanks to the direct integration into the IEC 61850 standard and the acceptance of all major energy automation companies. HSR/PRP technology is expected to be successful in other application fields as well, in particular factory automation. The technology is scalable in line speed (Gigabit speed is scheduled as future improvement to the standard) and can be flexibly adapted to incorporate other technologies, e.g. 1588v2 time synchronization.