Functional safety is an integral part of overall safety of your product. Devices needs to property respond to system inputs including probable errors of an operator, failure of hardware or software and environment changes. The traditional assessment of product safety is no longer sufficient - given the increasing complexity of technologies and associated risks it is necessary to proceed to a higher level.
IEC 61508, the general norm for functional safety, applies to the entire life cycle of electrical, electronic or programmable electronic (E/E/PE) systems and products. There are also other standards, such as EN ISO 13849-1, that deal with mechanical and pneumatic devices.
Manufacturers have to ensure that failures that may occur in their products or systems do not entail unacceptable risks.
Specific methods need to be implemented to create safe hardware and software - backup, use of diversity or internal tests to increase product resistance to accidental failures and system failures.
TÜV SÜD offers comprehensive services in the field of functional safety for manufacturers in many industrial fields such as automation, aerospace, automotive, railways, healthcare, engineering, nuclear engineering, process automation, and consumer products. We assess functional safety of a product – the assessed areas include prevention of accidental failures of a product or its parts and prevention of system failures that were unintentionally designed within a product. In our courses and workshops, manufacturers are trained in the field of standards according to IEC 61508. We perform assessment according to many international standards for functional safety such as ISO 26262, EN 50129, EN ISO 13849-1, and IEC 62061. A key component of our services is knowledge services that help our customers fulfil the requirements for functional safety already in the design stage.
Functional safety - conditions and processes
Risk assessment process
The risk assessment process has to identify whether or not functional safety measures need to be implemented and define what product-related actions are relevant from this perspective. The assessment further defines the critical limit of the safe performance of the given activities. The result of the process is the preparation of a list of safety features of a product and estimation of consequences in the case of a failure that is the basis for the assessment of functional safety. The aim of the entire process is to ensure that every function that was identified to be relevant from perspective of safety is performed with such a level of reliability that corresponds to its importance in the case of a failure.
Safety integrity level of a safety function
The Safety Integrity Level (SIL) defines the required reliability of a product from perspective of functional safety. SIL is classified in four categories - from the lowest level of SIL 1 to the highest level of SIL 4. SIL 1 suffices for safety features with relatively low criticality whereas features with a high level of criticality may require SIL 3 or SIL 4.
Assessment of functional safety
At lower SIL levels, companies may perform the assessment of functional safety by themselves, which is however suitable only in case that they have their own certified specialists in this area. Higher SIL levels require an independent assessor.
The assessment of functional safety is usually divided into several control points. These can be assessed repeatedly if the defined requirements are not fulfilled. Documentation on the life cycle up to a given point is assessed in every control point. In case you do not have such documents available, the control point needs to be repeated. The normal sequence of control points in the assessment is approximately as follows:
- Review of safety requirements, audit of the safety design management system
- Review of the requirements for hardware and software, test plan, validation and verification
- Review of the design of hardware and software
- Participation in hardware testing and software verification
- Participation in validation tests and results review
- Assessment of user documentation and instructions
- Assessment of complete technical documentation and documentation that maps the entire life cycle of a product