Machine Run-Down Testing

Machine safety is a critical element of every industrial environment. It not only protects workers from potential injuries, but also improves the efficiency and reliability of production processes. Machines that are not properly safeguarded can pose a serious risk to the health and lives of operators and others nearby. Proper risk management and the use of appropriate protective measures are therefore essential to maintaining a safe workplace. In this context, machine stopping time measurement becomes an indispensable part of the safety assurance process.

Machine Stopping Time Measurement: Key Principles of EN ISO 13855

Structure and scope of the standard

EN ISO 13855 addresses a range of machine safety issues, focusing on technical protective measures and their positioning in relation to the approach speed of parts of the human body. The document is divided into several key sections, including:

• Scope of the standard
• Normative references
• Terms, definitions, symbols and abbreviations
• Methodology for determining minimum distances
• Detailed rules for positioning different types of technical protective measures

The standard also specifies which approach speed values must be considered when designing protective systems and how to calculate the minimum distances from the detection zone to the hazard zone.

Basic terms and definitions

To understand and apply EN ISO 13855 correctly, it is important to become familiar with the key terms and definitions. Some of the most important are:

• Total system stopping time (T): The time interval from activation of the detection function until the hazardous machine function ceases.
• Minimum distance (S): The calculated distance between the technical protective measure and the hazard zone, required to prevent a person or part of a person’s body from reaching the hazard zone before the hazardous machine function ceases.
• Electro-sensitive protective equipment (ESPE): An assembly of cooperating devices and/or components used for automatic protective shutdown or presence detection, containing at least a sensing device, control/monitoring devices, and output signal switching devices.

Machine Stopping Time Measurement: Methodology and Rules for Positioning Technical Protective Measures

Methodology for determining minimum distances

Risk assessment according to ISO 12100 is an integral part of machine stopping time measurement. This process involves analysing the potential hazards associated with machine operation and identifying preventive measures aimed at reducing risk. In accordance with EN ISO 13855 and risk analysis according to EN ISO 12100, engineers must take into account body part approach speeds, system response time, and the effectiveness of the technical protective measures used. A thorough risk assessment makes it possible to implement appropriate safeguards, thereby improving machine safety and regulatory compliance.

EN ISO 13855 provides a methodology for calculating the minimum distances required to ensure machine safety. These formulas take into account the approach speed of parts of the human body toward the hazard zone and the response time of the protective system. The process should begin with hazard identification according to ISO 12100, followed by the detailed calculations described below.

General formula for calculating total system stopping time and minimum distances:

S=(K×T)+C

where:

• S – minimum distance,
• K – coefficient dependent on approach speed,
• T – total system stopping time,
• C – additional distance resulting from anthropometric data.

Example calculations for different approach speeds

1. Approach speed of an adult walking at a normal pace (1,6 m/s)
   • Assume that the total system stopping time is 0,5 seconds.
   • The additional distance C is 0,2 m.

S=(1,6 m/s×0,5 s)+0,2 m=0,8 m+0,2 m=1,0 m

2. Approach speed of the upper limb (2,0 m/s)
   • The total system stopping time is 0,4 seconds.
   • The additional distance C is 0,1 m.

S=(2,0 m/s×0,4 s)+0,1 m=0,8 m+0,1 m=0,9 m

Types of technical protective measures

EN ISO 13855 takes into account a variety of technical protective measures used to ensure machine safety under different operating conditions. The most important include:

1. Light curtains and light barriers (AOPD)
   • Light curtains are devices that emit beams of light and detect interruptions caused by a person or body part entering the hazard zone.
   • Light barriers operate on a similar principle, creating an invisible barrier whose interruption causes the machine to stop.
2. Laser scanners (AOPDDR)
   • Laser scanners are used to monitor larger areas and can detect movement in complex spatial configurations.
   • They enable precise detection of moving objects, which is particularly useful in dynamic production environments and supports safety functions in industrial automation.
3. Pressure-sensitive mats
   • These mats respond to pressure applied by people stepping onto them, making it possible to detect presence in the hazard zone.
   • They are used where it is necessary to ensure safety while still allowing free access to the machine.
4. Two-hand control devices
   • They require both hands to be used to start the machine, preventing accidental start-up.
   • They are used where it is necessary to ensure that the operator remains at a safe distance from the hazard zone when starting the machine.

Machine Stopping Time Testing: Practical Applications and Examples

Examples of practical application of the standard

Below are several examples illustrating the practical application of EN ISO 13855 in different industrial environments. Each example shows how technical protective measures can be implemented effectively to ensure machine safety.

Example 1: Using light curtains on a production line

In a manufacturing plant operating high-speed assembly machines, light curtains were installed along the production line. The curtains are positioned to detect any interruption of the light beam caused by a person or body part entering the hazard zone. The minimum distance between the light curtain and the hazard zone was calculated in accordance with EN ISO 13855, taking into account the approach speed of a person and the response time of the protective system. As soon as a person is detected in the sensing field, the machine stops immediately, preventing potential injuries. In practice, this approach should be supported by hazard identification in accordance with ISO 12100 so that the protective concept matches the actual risks present on the line.

Example 2: Using laser scanners in a warehouse

In a high-bay warehouse, laser scanners were used to monitor movement in the aisles between racks. The scanners are mounted at a height that allows them to detect the movement of both forklift trucks and employees. EN ISO 13855 was used to determine the appropriate minimum distances, ensuring that any movement within the detection zone is registered immediately.

When the scanner detects a person or vehicle approaching the hazard zone, the system automatically stops the forklift truck, minimizing the risk of collisions and accidents. This solution allows the warehouse to operate efficiently while maintaining a high level of safety for all employees. In such applications, design decisions are often linked to a broader understanding of the impact of Regulation 2023/1230/EU on particularly hazardous machines.

Example 3: Pressure-sensitive mats in a machine maintenance area

In a machine maintenance area, pressure-sensitive mats were installed to protect technicians carrying out repair work. These mats respond to pressure applied by people stepping onto them, making it possible to detect presence in the hazard zone. In accordance with EN ISO 13855, the mats are placed at an appropriate distance from the hazard zone, ensuring that the machine is automatically shut down if a technician steps onto the mat while the machine is operating.

This solution significantly improves safety during maintenance work by eliminating the risk of accidental machine start-up when a technician is in the hazard zone. As a result, machine maintenance becomes safer and more efficient. For facilities modernising older equipment, this may also form part of adapting machinery to current EU requirements.

Machine Stopping Time Testing: Challenges and solutions in implementing the standard

Typical problems encountered when implementing the standard

When implementing EN ISO 13855, companies may encounter a range of challenges. Below are some common issues and suggested solutions:

1. Inaccurate calculation of minimum distances
   • Solution: Make sure all calculations are carried out accurately in line with the standard’s guidelines. Regular training for engineers and operators can help prevent errors.
2. Lack of employee awareness and training
   • Solution: Provide regular training on safety principles and the application of EN ISO 13855. Make sure all employees understand the hazards and know how to use technical protective measures.
3. Technical issues with protective devices
   • Solution: Ensure regular inspection and maintenance of technical protective measures. Work with equipment suppliers to make sure the devices remain fully operational at all times.
4. Difficulties adapting the standard to specific working conditions
   • Solution: Tailor implementation of the standard to the specific working conditions, taking into account all unique aspects of the environment in question. Consultation with safety experts can help resolve site-specific issues.

EN ISO 13855 provides detailed guidance on the positioning of technical protective measures to ensure machine safety. Following these guidelines minimizes the risk of injury and improves safety in the workplace. Practical examples show how different technical protective measures can be used effectively in a variety of industrial environments. To support implementation, companies often combine these principles with technical documentation of machines under the new 2023/1230 Regulation and a clear EU Declaration of Conformity for machinery.

Industrial Automation and Machine Stopping Time Testing

Industrial automation plays a key role in modern manufacturing plants, where machine reliability and safety are top priorities. As part of this process, machine stopping time testing is an important element that helps ensure all equipment operates in compliance with safety standards, minimizing the risk of accidents.

In machine design and integration with automation systems, it is essential to consider the speed at which parts of the human body can approach the hazard zone. A design office responsible for production process automation must apply the guidelines set out in EN ISO 13855 in order to position technical protective measures correctly. This engineering work should also be preceded by risk assessment according to ISO 12100 so that protective distances reflect the real operating context.

This standard is also essential during safety audits, which assess machine compliance with minimum requirements and other regulations, such as the Machinery Directive 2006/42/EC and the Machinery Regulation 2023/1230. Auditors often use the results of machine stopping time testing to verify that all equipment meets the relevant criteria for CE certification of machinery and can operate safely in a production environment.

As part of the machine conformity assessment process, CE marking is granted only to equipment that has passed rigorous safety testing. An industrial automation integrator must ensure that all system components, including machine guards and PLC programming systems, operate in accordance with harmonized standards. Production automation without appropriate protective measures could lead to dangerous situations, which is why machine stopping time testing is an indispensable step in the design and implementation process. In this context, manufacturers also need to understand the broader Regulation on Machinery 2023/1230/EU and, where applicable, the requirements for a CE nameplate under Regulation 2023/1230/EU.

In the context of rapidly evolving industrial automation, machine stopping time testing is also crucial when adapting machines to minimum requirements. Engineering outsourcing and support from specialists in production process automation can be a beneficial solution for companies that need help implementing advanced safety systems.

Conclusions and recommendations

• Recommendations for designers and engineers: The guidelines of EN ISO 13855 should be followed closely when designing machine safety systems. Regular reviews and updates of protective systems are essential to maintaining a high level of safety.
• The importance of continuous improvement of protective measures: Technology and working methods are constantly evolving, so it is important to regularly update and adapt protective systems to new requirements and hazards.
• Recommendations for further research: Further research is needed into new protective technologies and their effectiveness under different operating conditions. This research should also take into account the specific needs of different industrial sectors.