Safety of High Tech Controls

Functional Safety is the fundamental of overall safety

The 2008 World Safety Congress helped to inform workplace safety professionals of some new technology issues facing workers in the increasingly automated workplace. Among these were control system issues, such as how to improve safety when closer human-to-robot interactions are needed in critical manufacturing process steps, and how machine-vision cameras can be used to identify when workers come into close proximity of hazardous machinery. As such technologies become more pervasive in the workplace, high-tech control systems are becoming an increasingly important part of the equation in worker safety.

UL Corporate Research has been at the forefront of understanding emerging technologies and how they impact safety. Critical to this understanding has been the observation of trends toward increased safety-related performance in almost all aspects of product safety. In order to address the safety-related performance of products, UL has been collaborating in the international arena to develop Functional Safety requirements as well as efficient and cost-effective methods to assess products to these requirements.

Functional Safety is fundamentally that aspect of overall safety, which addresses the inputs of a system or device relative to its outputs. In particular, it addresses how the system or device may be involved in detecting a potentially hazardous situation and initiating a corrective or preventative action to mitigate the risk. This involves some challenging tasks: First, defining the scope (system, subsystem, or device), next, understanding the relevant failure modes of the equipment, and finally, determining the level of appropriate risk reduction.

When defining the scope of equipment involved in Functional Safety, it is critical to understand the “intended use” or “application.” This is what drives the meaning of “safety” relative to that particular equipment, such as the consideration of whether someone might be injured if the equipment does not function as intended. In this step, techniques such as Hazard Based Safety Engineering may be used to identify sources of hazardous energy, and establish the need to minimize the transfer of that energy to the human body. Once this has been determined, a more in-depth examination must take place to understand the technologies used in building the equipment, as well as the failure mode and stress conditions that could cause that technology to fail or misbehave in potentially dangerous ways.

Almost every conceivable workplace can be affected by state-of-the-art electronics and control system technologies. While embedded systems and software control much of today’s workplace equipment, and new “nano-enabled” technologies are on the horizon, even the most “low tech” jobs employ workers whose health and welfare is considered during the development of “high tech” requirements, such as those for radiated emissions from nearby cellular telephone towers or radio and television stations.

Depending on the type of equipment being addressed, the final step in applying the concepts of Functional Safety may be legislated, industry directed, or determined by the corporate culture and safety-mindset of the individual manufacturer within the constraints of the applicable voluntary standards. This final step, risk management, is in fact not a “final” step, but should be kept at the forefront of thinking throughout the entire product development lifecycle, specifically targeting the equipment’s overall “safety lifecycle” to provide for the desired Safety Integrity Level (SIL) or Performance Level (PL).

by Anura Fernando and Dr. Pravinray Gandhi, UL Corporate Research

Anura Fernando was one of the UL representatives who provided expert sessions at the World Congress on Safety and Health at Work, Seoul, Korea 2008.