Safety Integrity Level (SIL) functions for railway applications

Safety Integrity Level (SIL) functions for railway applications

Safety Integrity Level (SIL) functions for railway applications
Safety Integrity Level (SIL) is an indicator of the relative risk-reduction provided by a safety function. EKE-Electronics helps you develop SIL functions to make your trains safer and more reliable.

EKE-Electronics has expertise designing and manufacturing systems with Safety Integrity Level (SIL) functions. We have developed systems up to SIL-2 for various safety functions, including speed measurement, temperature measurement and door operation. Please read below for a more exhaustive list of safety functions.


STANDARDS

The SIL notion results directly from the IEC 61508 standard which is not railway specific. For the rail industry, CENELEC has developed the EN 50126, EN 50128 and EN 50129 standards which were derived from the IEC 61508 to meet railway specific requirements.

Following the CENELEC standards ensures compliance with the IEC 61508. The CENELEC standards are:

Icon Standard EN 50126: The specification and demonstration of Reliability, Availability, Maintainability and Safety (RAMS)

Icon Standard EN 50128: Railway applications - Communication, signalling and processing systems - Software for railway control and protection systems

Icon Standard EN 50129: Railway applications - Communication, signalling and processing systems - Safety related electronic systems for signalling


WHY IMPLEMENTING SIL

The development of Safety Integrity Levels fulfils the need for more approachable and systematic safety management. The SIL probabilistic approach helps to determine the risks associated with a safety function, system or component and to set an acceptable risk level for it.

Four Safety Integrity Levels are defined, ranging from SIL-1 to SIL-4:


    PFH*   RRF**
SIL-1    10-5 -10-6   105 -106
SIL-2   10-6 -10-7   106 -107
SIL-3   10-7 -10-8   107 -108
SIL-4   10-8 -10-9   108 -109

*PFH: Probability of failure per hour
**RRF: Risk reduction factor


As described in the table above, SIL-4 provides the highest risk reduction factor and is reserved for highly critical safety functions that may cause important casualties and must be prevented at all costs.

For most safety functions in a train, SIL-1 or SIL-2 will provide acceptable risk levels. No matter the level, SIL functions contribute to make your trains safer.


APPLICATIONS

Safety Integrity Levels can be assigned to virtually any function presenting a safety risk. Examples of SIL functions developed by EKE are listed below:

SIL-1  Speed monitoring and display
Analysis of several speed measurements and display of the value to the train crew.

SIL-1  Monitoring of axle box bearing temperature
Measurement of the axle bearing grease box temperature. Safe Contact Digital Output. Read more

SIL-2  Monitoring of axle box bearing temperature
Measurement of the axle bearing grease box temperature. Safe Contact Digital Output. Redundant system. Read more



SIL-2  Train speed measurement
Measurement of train speed in bogie and rodal. Safe Contact (CS) Digital Output.  Redundant system.

SIL-2  Lateral acceleration monitoring
Measurement of acceleration peaks in bogie and rodal. Safe Contact (CS) Digital Output. Redundant system.

SIL-2  Fire detection System monitoring
Reading fire detection signals and SIL-2 data transfer via MVB. Redundant system.

SIL-2  Safety communication management
Receive, handle and send safety communication data such as temperature pattern, speed data. Validate train configuration information. Redundant system.

SIL-2  ASDO (Automatic Selective Door Operation)
Bringing flexibility by enabling customized door opening based on platform and safety requirements. Read more



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EKE Trainnet SIL Functions



EKE-Electronics Ltd
Piispanportti 7
02240 Espoo
Finland
Tel +358 9 6130 30

 

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