Functional safety - safety-related control systems

The Machinery Directive 2006/42/EC requires performing a risk assessment. In this document all risks must be analyzed and the risk has to be assessed without countermeasure.

If the countermeasure does not prevent/minimize by inherently safe design or mechanical protection device, such as cover, so come complex electronic, electromechanical (eg, relay), non-electrical (eg hydraulic, pneumatic) safety-related (n) control function (s) as solutions to wear.

The evaluation of the safety-related control system (s) is based on the following standards:



The following steps are necessary in order to determine and evaluate a "safety-related control function" .

1) Implementation of risk assessment to

  • determine the required performance level (PL) according to risk graph in EN ISO 13849-1
  • determination of the required safety integrity level (SIL) according to risk graph in EN 62061 (for machines) and EN 61511 (for process plants)

2) Structure of the safety function (planning of the safety function)



3) Calculation of the achieved performance level and safety integrity level

4) Validation and Verification

Validation: Confirmation by examination (e.g. tests, analysis) that the Safety-Related Electrical Control System meets the functional safety requirements of the specific application.

Verification: Confirmation by examination (e.g. tests, analysis) that the Safety-Related Electrical Control System, its subsystems or subsystem elements meet the requirements set by the relevant specification.


EXAMPLE: Verification activities include:

  • Reviews on outputs (documents from all phases) to ensure compliance with the objectives and requirements of the phase, taking into account the specific inputs to that phase
  • Design reviews
  • Tests performed on the designed products to ensure that they perform according to their specification
  • Integration tests performed where different parts of a system are put together in a step-by-step manner and by the performance of environmental tests to ensure that all the parts work together in the specified manner

The V-model differs from the classical forms of the phase of application development models (waterfall model, spiral model) by the inclusion of quality assurance. Quality assurance is done by assigning activities of validation and verification activities of construction in the process. The validation is the review of the utility; with the verification verification of compliance with the requirements is made.
Faults are detected (by verification) and redundant properties (through validation) in the V-model usually earlier than in the workflow after the waterfall model or the spiral model and thus minimizing costs in the project due to the prominence of ensuring quality as a separate sub-model. The acceptance by a contracting entity is simplified.

Sequence of phases and product flow in the V-model 97 (further information or source: here ...)

We can assist you during all the steps to reach the performance level (PL) and Safety Integrity Level (SIL).