Protect a user from technology and technology from users
Protect a user from technology and technology from users
Functional safety is, simply put, “Protecting a user from technology”. It also protects technology from users. More technically however, the definition of Functional Safety is, “Systems that lead to the freedom from unacceptable risk of injury or damage to the health of people by the proper implementation of one or more automatic protection functions (often called safety functions). A safety system consists of one or more safety functions.”
A simple example of a functional safety system could be a domestic coffee maker with a sensor that detects the coffee temperature or the volume of coffee in the flask. If the sensor detects the temperature has exceeded a threshold, it switches the heating element off, or if the volume is greater than anticipated, it halts the percolation process.
More complex examples may include a railroad crossing barrier or an automated robot in an industrial setting. In the first example, the functional safety system would detect the approach of an oncoming train and lower the barrier. In the other example, the system registers the presence of a person the workspace and puts the robot into a safe state, i.e. stopping it or moving it to a safer position.
It is important to note that a functional safety system is an active part of the system, it will react to predefined triggers and instruct the overall system to make an active change. Fire resistant doors or clothing are not considered a functional safety system as they perform their function passively.
At its core, functional safety is important because its sole purpose is to protect users from harm. Complex technology is an integral part of our day to day activities, and we demand that they are safe to use. Functional safety is becoming more important in products of all types, industrial and consumer, as the types of controls being used are increasingly more complex and are safeguarding against many more instances.
In manufacturing facilities for instance, functional safety is critical to safe operation. Functional safety systems can give operators far better operational metrics and control of the equipment under use. From a business standpoint – functional safety allows manufacturers to operate closer to their margins with confidence in a well-defined functional safety environment. This benefits them in terms of increased efficiencies, fewer downtimes, and the resulting cost savings.
Simply, in many instances, certification is required regulatory authorities. Without certification a product cannot enter the marketplace. There may be local, national, or international requirements depending upon your product, it’s intended use, and where it is to be marketed. Even when there is no legislative requirement for a component or product to be functional safety certified, in many cases it is required by the end user.
It is also important to remember that some insurance companies may require functional safety certification before they offer coverage. In terms of product liability, compliance with standards serves as proof that product/application meets state-of-the-art safety requirements.
An important point to remember is that some regulatory authorities and end users, may demand that certification be carried out by an independent, third-part qualified certifier. Demonstration of independent review is important to users’ acceptance of a product; a lack of may lead to questions of whether the product has been looked at with a fully critical eye.
Getting a product certified for functional safety is a process that should ideally involve your developers, your assembly teams, and your functional safety certifying organization, and should start in the early development stages. This allows you to build robust development plans in which the assessment process will follow through the product development lifecycle.
Whilst discussing your development plan with the certification provider they will be able to provide advice – such as a safety system may require two channels rather than a single channel if you need a Safety Integrity Level (SIL) 3. The plan should also include agreed milestones to verify and validate your product for functional safety as you are developing/building it.
There are risks involved in leaving functional safety to the end of your product development as you may find out too late that your product does not meet functional safety criteria and you have to go back to the drawing board. Planning early can mitigate costly reworks or recalls.
When it comes to selecting a functional safety testing and certification organization, there are many to choose from. Providers can vary in size, from small specialist companies offering niche services all the way to large companies offering integrated product development programs. So, with such a variety of options to choose from, what aspects should you evaluate when making this important decision?
There are essential questions that you should ask of any provider:
Many regulatory authorities, end users, and insurance groups demand the use of independent, non-biased, third party certifying organizations. Some manufacturers prefer this approach too as it demonstrates transparency, giving their customers greater confidence in their products.
All development plans, and certification processes are unique and as such there is no single answer. However, functional safety assessment usually follows your development plan, so there shouldn’t be any surprises. This means that the time taken for your assessment is not determined by the functional safety certifier but your own development process.
It is best practice to put your development team and your certifying provider together very early in your design stages. This will allow your teams to develop robust plans that include functional safety milestones – catching any failings as they occur in real-time will save you time and money instead of retroactively addressing issues.
The basic Functional Safety standard is IEC 61508 and it is applicable to all industries. Although this standard covers all industries, each industry has its own nuance, therefore so many have developed their own standards based off IEC61508. In the section below, we examine some specific industry standards. It is important to note that when deciding which safety standard to use that the most industry-specific standard has precedent.
The ISO 26262 standard applies to electrical and electronic systems consisting of hardware and software components in vehicles. It defines the requirements to be met by the safety relevant function of the system as well as by processes, methods and tools which are used within the development process.
The standard provides an automotive safety lifecycle and supports tailoring the necessary activities during these lifecycle phases. It determines an automotive specific risk-based approach for determining risk classes (Automotive Safety Integrity Levels, ASILs), and uses ASILs for specifying the item’s necessary safety requirements for achieving an acceptable residual risk. And lastly, identifies the requirements for validation, verification, and confirmation measures to ensure a sufficient and acceptable level of safety being achieved.
First published in 1996, EN 954-1 was used as the functional safety standard for parts of the control system both for machine builders and end users for nearly fifteen years. But with technology rapidly advancing, this standard was no longer able to keep up with systems and components being developed. In 2007, EN 954-1 was replaced by two new standards – EN ISO 13849-1 and IEC 62061 – designed to deal with these changing technologies.
EN ISO 13849-1 addresses the safety of all system technologies including mechanical, hydraulic, and pneumatic products. Where safety functions are to be performed by safety related parts of the control system (SRP/CS), EN ISO 13849-1 can be used to show compliance with the EHSRs of the Machinery Directive 2006/42/EC.
IEC 62061 refers to the generic functional safety standard considers the whole lifecycle of electrical, electronic, or programmable electronic (E/E/PE) systems and products. This is the machinery specific implementation of IEC/EN 61508. Compliance with the EHSRs of the Machinery Directive 2006/42/EC can be demonstrated through the implementation of this standard.
The scope of IEC 62061
| IEC 62061 | ||||
| Machinery sector hardware | Machinery sector software and application software | |||
| In scope | Not in scope | In scope | In scope | Not in scope |
| Design of low complexity subsystems | Design of complex subsystems | Integration of subsystem into a safety related control system | Using hardware predesigned according to IEC 61508 or other functional safety standards | Design of complex subsystems |
The IEC 60601 standard is in fact a series of technical standards that ensure the safety and efficacy of medical electrical equipment. It deals with the basic safety, and essential performance requirements of medical electrical equipment, and serves to ensure that no single electrical, mechanical, or functional failure shall pose an unacceptable risk to patients and/or operators.
IEC 60601 is a hazard-specific standard. It provides requirements for evaluating the common hazards associated with electromedical products. Its scope is to protect against the likelihood of hazards including:
The rail industry is one of our oldest forms of mass transit. The technology used has come a long way from those early days of steam and coal; it has become increasingly complex, automated, and autonomous. The demand for confidence in the functional safety of these systems has moved forward in step too.
The CENELEC EN 5012X series of functional safety standards (or the equivalent IEC standards) are designed to ensure that safety risks due to hazards caused by malfunctioning behavior of systems are reduced to an acceptable level. The series of identical standards; both standards published by CENELEC and IEC respectively, are:
As with other functional safety standards, the EN 5012X series are risk-based standards. Risk assessments are conducted to determine the safety functions required, and the performance level these functions need to mitigate the risks.
EN 17206 is the functional safety standard for the entertainment industry. Released in 2019, it is the first standard defining a framework for functional safety specifically for the entertainment industry. The standard covers machinery for stages and other production areas such as theatres, exhibition halls, and studios.
Safety Integrity Levels are defined in most other functional safety standards. However, the determination of SILs can different between different standards, and care should be taken to not confuse them. This becomes even more interesting in EN 17206 as safety standard risk assessments are typically written with manufacturing equipment in mind, and these don’t translate well for entertainment settings. EN 17206, Annex D does however provide an, “entertainment industry calibration”, to help provide direction.
IEC 60335 is the safety standard for electrical appliances for household and similar purposes. It covers appliances with voltage ratings not more than 250V for single phase appliances, and 480V for other appliances. Appliances not intended for household use but are used by laymen in other environments such as shops, farms and light industry are also covered by IEC 60335.
The standard comprises of two main parts:
When developing safety systems software, tools become more and more important. However, the software tool used in development needs to comply with predefined criteria. The requirements of software tool qualification in functional safety development projects are therefore of concern to many industry stakeholders.
In certification projects, this topic is often an area of risk and uncertainty as more and more certified tools are available, but it’s not always clear which tool would lead to the highest benefit in the development project. This can lead to drawn-out discussions during a project lifecycle, causing costly delays.
Tool certification is used for development in safety-related environments such as in the automotive, automation, railway, medical or nuclear sector.
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