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.
Safety Integrity Levels
The systems covered under functional safety are designed to automatically prevent dangerous failures or to control them when they occur. It helps us to design a system that can execute specific functions correctly, even under non-intended use (or sometimes even misuse).
Functional safety is the part of the overall safety of a system or piece of equipment that depends on automatic protection operating correctly in response to its inputs or failure in a predictable manner (fail-safe). The automatic protection system should be designed to properly handle likely human errors, systematic errors, hardware failures and operational/environmental stress.
The main hazards to mitigate with EKE-Trainnet safety applications are derailment, collision, fire, personal damage, material damage and environmental pollution. Our solutions are determining and analysing causes e.g. overspeeding, mislocated train, equipment failures related to wheels, bearings, brakes or doors as well as human errors. In addition, EKE designs control measures deriving safety requirements like warnings and alarms, speed limitations, traction disabling, emergency brakes or cutting power to mention a few.
Four Safety Integrity Levels
Four Safety Integrity Levels are defined, ranging from SIL 1 to SIL 4. SIL 4 provides the lowest functional failure rate and is reserved for highly critical safety functions that may cause severe casualties and must be prevented at all costs. SIL 4 provides the lowest functional failure rate and is reserved for highly critical safety functions that may cause severe 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 making your trains safer.
The SIL notion results directly from the IEC 61508 standard. 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. EKE-Electronics Ltd’s functional safety solutions comply with these standards.
Safety Integrity Levels (SIL) are defined levels of risk reduction applied to safety-related systems. They are used to quantify the reliability and performance of safety functions in industries such as rail, industrial automation, and process control. SIL levels range from SIL 1 to SIL 4, with SIL 4 providing the highest level of risk reduction.
The SIL notion results directly from the IEC 61508 standard. EKE-Electronics Ltd’s functional safety solutions comply with these standards.
Each SIL level corresponds to a target probability of failure on demand (PFD) or failure per hour (PFH), as defined by international safety standards IEC 61508 (functional safety for electrical, electronic, and programmable systems). 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. The higher the SIL level, the lower the acceptable likelihood of a dangerous failure occurring.
For example:
- SIL 1 provides a lower level of risk reduction and is typically used for non-critical applications (TFFR: 10-5 – 10-6)
- SIL 2 is used for systems where failure could cause significant operational disruption or hazards. (TFFR: 10-6 – 10-7)
- SIL 3 is applied to systems where failure could result in severe injury or fatalities. (TFFR: 10-7 – 10-8)
- SIL 4 is the highest level and is reserved for applications where failure would lead to catastrophic consequences. (TFFR: 10-8 – 10-9)
To achieve a specific SIL level, a system must meet strict requirements for hardware reliability, fault tolerance, and systematic integrity, including development processes that minimize errors and failures.
In the railway industry, SIL certification is essential for ensuring the safety of train control, signalling, and automation systems.
*TFFR: Tolerable Functional Failure Rate per hour
EKE-Electronics’ SIL Safety Capability
EKE-Electronics has expertise in designing and manufacturing systems with Safety Integrity Level (SIL) functions. We have developed systems up to SIL 2 for various safety functions, including door operation, hot axle box detection and driver vigilance.
