A comprehensive approach to safety-related control systems

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In the dynamic world of industrial engineering, safety is paramount. Yet, a significant gap persists in the knowledge and competence required to design and maintain effective safety-related control systems. This gap often leads to inadequate safety measures, risking both personnel and operational integrity. Euchner provides valuable insights into some of the common challenges encountered and offers effective solutions to address them.

The increasing complexity of modern industrial machinery, combined with the stringent demands of national and international safety standards, including EN 13849 and IEC 62061, presents substantial challenges for organisations. Many facilities struggle with a fundamental lack of understanding regarding the design, implementation, and maintenance of safety-related control systems. This knowledge gap can lead to safety systems that are either overly simplistic or excessively complex, both of which jeopardise safety and operational efficiency.

Common issues

Misidentification of safety functions: Without a comprehensive understanding, essential safety functions may be overlooked or improperly defined, leading to ineffective risk mitigation. It is crucial that each safety function is assigned a specific Performance Level (PLr) according to EN 13849. This ensures that the safety measures are adequate and effective. In practice, many engineers mistakenly assign a single Performance Level to an entire machine rather than evaluating each safety function individually. Even functions relating to guard-locking or reset need to be considered when they apply to the safety integrity of the equipment.

Inappropriate selection of safety devices: Choosing incorrect or incompatible safety devices can cause system failures and result in non-compliance with critical safety standards. Examples include the selection of ‘Energise to Lock’ guard interlocks where residual hazards remain, e.g. a running down saw blade, the use of easily bypassed low-coding devices, series connected devices without fault detection.

Insufficient integration and testing: Inadequate integration, a lack of validation planning, and a lack of rigorous testing can render safety systems unreliable, increasing the risk of failure during actual operations. This is especially necessary when programmable or configurable safety controllers are used with software.

Maintenance practices: Without adequate training, maintenance personnel may neglect essential checks and updates, leading to the deterioration of safety system performance over time. Production pressures compound these issues; unfortunately, often the safety interlocks are overridden when issues do occur.

Safety Function Identification

Comprehensive risk assessment: Conducting a thorough risk assessment is the first step in identifying all potential hazards associated with machinery operations. Each hazard should be evaluated to determine the necessary safety functions to mitigate the associated risks effectively.

Assigning appropriate Performance Levels (PLr): Once safety functions are identified, it is crucial to assign a Performance Level (PLr) to each control-based function based on the severity of potential harm, the frequency of exposure to the hazard, and the possibility of avoiding the hazard. You wouldn’t normally use a washing machine door switch to protect an operator from entering a robot cell, so how do you determine the required integrity? This detailed assessment ensures that each safety function is adequately addressed and that the safety measures are proportional to the risks involved. Engineers often make the mistake of defining a single PLr for an entire machine, which can lead to inadequate safety measures. Each safety function may have different risk parameters and, therefore, may require different PLr’s. Proper training and a clear understanding of EN ISO 13849 guidelines are essential to avoid this common pitfall.

Documenting and verifying safety functions: It is vital to document each safety function and its corresponding PLr, showing how the PLr has been achieved. Verification and validation processes should be in place to ensure that the safety functions meet the required performance levels and that the protective measures are effective.

Getting it right

David Dearden, Country Manager at machinery safety expert Euchner, said: “Ensuring a safe machine hinges on the backbone of competence and knowledge, stretching from equipment designers to machinery operators. Organisations must prove their teams are equipped with the essential skills and expertise to design, build, and test robust safety-related control systems. This is where comprehensive training makes all the difference.”

Recognising the need for enhanced competence in the industry, Euchner offers a range of training programs designed to equip engineers and technicians with the knowledge and skills required to design, implement, and maintain effective safety-related control systems.

Euchner’s training programs have a proven track record of enhancing safety competence across various industries. By empowering engineers and technicians with the necessary knowledge and skills, these programs help organisations achieve higher levels of safety and operational efficiency.

Case Study

A large manufacturing facility was facing significant challenges with its safety systems due to a lack of knowledge and competence among its engineering staff. The facility had experienced several near-miss incidents, highlighting the need for improved safety measures.

Challenges identified by the company included:

  • A single PLr applied to all machinery functions, generally misapplied.
  • Inadequate risk mitigation for specific high-risk functions.
  • Non-compliance with EN 12100 (Risk Assessment), EN 13849 (Control Systems) & EN 14119 standards (Interlocking).

The solution identified included:

  • A detailed risk assessment. With the assistance of Machinery Safety expert Euchner, the site team conducted a comprehensive risk assessment, identifying distinct safety functions and their specific risk parameters.
  • Assignment of PLrs. Each safety function was assessed against the contribution made to the reduction of the risk, and then assigned an appropriate PL based on its unique risk profile.
  • System redesign and training. The safety system was redesigned to incorporate the new PLs, and facility engineers were trained on the proper identification and application of the Performance Levels in accordance with EN 13849. This includes wiring structure and device selection.

The results achieved included:

  • Enhanced safety compliance. The facility achieved full compliance with the relevant aspects of the legislation in place, including the Provision & Use of Work Equipment Regulations (PUWER) and the Management of Health and Safety at Work Regulations.
  • Improved risk mitigation. Safety measures were tailored to each function, significantly improving risk mitigation.
  • Increased operational efficiency. The facility experienced reduced downtime and improved overall efficiency due to more effective safety systems. Unnecessary costs were avoided through the use of safety solutions designed at a more granular level on the machine determined by the risk being safeguarded, e.g. not using a fully coded RFiD locking device when a simpler low-coding device is adequate.

The future of industrial safety

As technological advancements like safety networks, e.g. PROFISAFE, and Safety over IO-Link, become more prevalent, there is an increasing emphasis on the need to demonstrate competence in safety system design and implementation. Regulatory bodies and industry standards now require organisations to validate that their engineers possess the necessary expertise to handle advanced safety technologies and software. This shift underscores the importance of comprehensive training programs that equip engineers and technicians with up-to-date knowledge and skills. By staying abreast of these evolving trends and ensuring their teams are well-trained, organisations can effectively meet the challenges of modern machinery safety and maintain compliance with stringent safety standards.

www.euchner.co.uk

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