The provisions of the Machinery Directive must be complied with when planning, designing, significantly modifying, linking to form a whole and completing, importing and placing machinery on the market. In this context, the special regulations for the safety and reliability of control systems play a decisive role.
The risk assessment must be started at the beginning of the design phase and then continued throughout the process. In this process step, the manufacturer or operator identifies possible hazards on the respective machine, based on the limits of the machine and the people who work with it in the possible life phases. The hazards identified in this way are then factorized. Risk-reducing measures must then be taken, in the order of design, technical and indicative measures. If this results in requirements for technical protective measures, these are practically implemented on the basis of harmonized standards - for example the sector standard EN ISO 13849-1.

The functional safety requirements must always be documented accordingly. Particular attention must be paid to the interface between the manufacturer and the system integrator or the electrical design. These tasks for implementing the technical measures - such as control cabinet construction - are often assigned by the machine manufacturer. Preparing the operating instructions, drawing up the declaration of conformity and then affixing the CE mark to the machine are the final steps before handover to the operator.
Trial operation during commissioning is also particularly important for the machine manufacturer. Because safety equipment may not yet be fully functional, the tests must be safeguarded with additional measures - such as temporary barriers and instructions.

Proven diligence

Simplified 'safety life cycle' for machine manufacturers.

© Phoenix Contact

It should not be forgotten that, in addition to the Machinery Directive and the harmonized standards, other directives - such as the EMC or ATEX Directive - may also be relevant. The 'safety life cycle' designed by Phoenix Contact visualizes a process-optimized implementation of the normative and legal framework conditions. If users base their procedures on this 'safety life cycle', they not only receive proof that they have worked conscientiously and carefully, but also protect themselves in the event of legal action.
The machine manufacturer therefore often commissions system integrators or electrical design departments to implement the functional safety requirements listed in EN ISO 13849-1, among others. For this purpose, the machine manufacturer provides detailed information from the risk assessment. In this phase, Phoenix Contact provides support by having specialists from the company help create and check the risk assessment or develop a safety concept for the machine together with the manufacturer from an existing risk assessment. This enables a seamless transition to the engineering phase, in which the individual safety functions are specified in detail and the safety integrity is verified - for example by using the 'Sistema' software.

Based on the specification, validation planning is carried out in the next engineering step. This defines all the necessary tests for the functional testing of the safety functions. Since commissioning may take place under time pressure, validation planning is particularly important. This is because it protects the commissioning engineer and reduces the risk of systematic errors during commissioning.
Depending on how the safety functions have been designed, a decision must be made as to when and how the individual measures, safety parameters and parameters are to be checked. In this context, there is talk of verification of the results, which is often equated with validation. It is crucial that all safety-relevant specifications are checked at the right points. Here too, the 'safety life cycle' provides assistance, as it allows the selection and definition of the tests required for the respective application. If safety-oriented software is used, its validation helps to increase safety during commissioning. The final phase of validating all safety functions after commissioning ensures that the operator receives a flawless and safe machine when it is handed over.

Continuous reflux

Preparation of the validation on the machine on the basis of the created test plans.

© Phoenix Contact

In accordance with the Machinery Directive, risks are identified and evaluated as part of the risk assessment and risk-reducing measures are defined. As described, this phase accompanies the entire development process of the machine. It is wrong to assume that a risk assessment is created at the beginning of the design process and then no longer comes into play. Instead, the risk assessment must be started as early as possible. In most cases, findings that arise during the engineering phase are fed back into the iterative risk assessment process. Subsequent changes in particular often result in a high potential for error, which must be avoided. Phoenix Contact supports users so that the findings from subsequent phases are consistently taken into account in the risk assessment.

In the subsequent development stage, manufacturers can create a comprehensive safety concept for their machine on the basis of Phoenix Contact 's experience or have the existing concept checked and supplemented. The safety concept is the central component of functional safety. Therefore, the correlations and links to the risk assessment, as well as the subsequent phases, must be correct and comprehensible for all those involved in the project. This is made possible by using the 'safety life cycle'.