Safely keeping pace with the wireless evolution
As the trend towards wireless safety continues, Neil Dyson highlights the need to ensure that wireless controls are 100% reliable.
There is a growing trend for wireless modules to be added into everyday products, beyond the more traditional market of laptops and mobile phones. So it comes as no surprise that the machinery industry is following suit as wireless connectivity becomes the expected norm.
One such area is wireless safety-related control systems. As the technology improves this type of system will grow in popularity, given the benefits of faster response times and a more flexible installed base. Wireless safety foot controls, for example, are now available and offer distinct advantages as they are flexible to position and easy to mount – wherever the operator can monitor the process most easily.
While wireless technology affords flexibility in terms of how equipment can be deployed across a site, it does have limitations, which is a concern for safety systems which require 100% reliability.
One such limitation is the sensing range between receiver and transmitter, the strength of which will depend on the local conditions. The radio signal can be strongly affected by conductive materials, as well as other sources of radio interference, and can sometimes lead to a dead spot for wireless connectivity. This can be caused by metal parts, such as wall armour, insulation and metal foils, which are known to reduce the penetration of radio waves to less than 10%.
So, how can machinery manufacturers ensure the reliability of their wireless safety controls and how can machinery end-users be assured of their own personal safety while operating equipment?
The Radio Equipment Directive 2014/53/EC (RED) was published in the Official Journal of the European Union on 22nd May 2014. As of June this year, it superseded the Radio and Telecommunications Terminal Equipment Directive 1999/5/EC (R&TTE), which was originally published in 1999. Until June 2017, manufacturers have the option of using the R&TTE Directive or the RED. However, from June 2017, the RED is mandatory, and economic operators (manufacturer, importer, distributor, authorised representative), which import, market or sell radio equipment and devices in the EU must comply with the RED.
This means that, having become familiar with the implementation of the R&TTE compliance standards over the last seven years, manufacturers of radio equipment, such as machinery wireless safety functions, now face a new set of requirements. Indeed, the new RED requires a shift in mind-set, as it introduces clearer obligations for all economic operators. As both the requirements and the number of products that fall under the RED have changed, so many economic operators are finding achieving compliance to be a significant challenge.
Products which fit within the following definition are subject to the RED: ‘Radio equipment – an electrical or electronic product which intentionally emits and/or receives radio waves for the purpose of radio communication and/or radiodetermination, or an electrical or electronic product which must be completed with an accessory (such as an antenna) so as to intentionally emit and/or receive radio waves for the purpose of radio communication and/or radiodetermination.’
Don’t cut corners
In order to reduce both costs and time to market for new equipment many machinery manufacturers will rely on the use of wireless modules that already meet some or all of the RED’s essential requirements. However, once these modules are integrated into another product, the regulatory requirements will change as the host machine falls within the scope of the RED. Under the RED, the manufacturer must also take into account reasonably foreseeable conditions – use of the product outside of its intended use, for example.
Manufacturers must also document risk analysis and assessment to determine their compliance strategy and the measures taken to reduce the compliance risks.
The most common method of demonstrating compliance with the RED essential requirements would be by using ‘Harmonised Standards’. These are written and published under an EU mandate, and provide a ‘presumption of conformity’ (or compliance), provided they are applied in full. Harmonised Standards are always evolving, so it is important to keep up to date if they are to continue placing products on the EU market.
While a wireless module can be compliant with the RED, if it is then fully integrated into a machine, which is normally outside the scope of the RED, then the machine would fall within its scope and the machinery manufacturer would need to draw up their Declaration of Conformity (DoC) accordingly.
The RED’s wide-ranging changes demand some significant adaptations as to how radio equipment is manufactured and supplied, and therefore it has major implications for machinery manufacturers integrating wireless safety functions. It is essential then, that those in the supply chain understand their specific obligations so that their equipment complies and can continue to be sold on the European market.
The manufacturer of the final product is responsible for overall compliance and must take responsibility for the wireless module compliance, as well as for the final host product. Ideally, the manufacturer of the wireless module should provide clear instructions to the machinery manufacturer about the correct integration of the module, including details of how to comply with the wireless regulations.
As we see the increasing move from wired to wireless safety functions, it is vital that they are capable of taking the necessary actions to terminate a hazardous event and achieve a safe state to keep operators from harm. The market surveillance authorities can come down hard on manufacturers that supply non-compliant equipment to the market, while machinery end users must also ensure that their machine manufacturer is aware of these new requirements, and that they only employ fully complaint wireless-enabled equipment.
Neil Dyson is business line manager for Machinery Safety at TÜV SÜD Product Service, a global product testing and certification organisation.>
Source: Control Engineering Europe - All Articles