The deployment of Ultra-wideband (UWB) Real-Time Location Systems (RTLS) in hazardous environments presents a significant leap forward in the precision of asset and personnel tracking. ATEX and IECEx compliance is fundamental.
In the article, we present a technical framework for designing and deploying UWB RTLS solutions that comply with the stringent safety standards for explosive atmospheres prevalent in the oil and gas, chemical, and mining sectors.
The Unique Advantages of UWB in Hazardous Environments
The fundamental physics of UWB technology offers inherent safety advantages over traditional Radio Frequency (RF) systems.
Unlike continuous-wave technologies, UWB transmits data in a series of very short, low-power pulses spread across a wide spectrum of frequencies. This low power spectral density significantly reduces the energy concentrated at any single frequency, minimizing the risk of generating a spark or a thermal hot spot that could ignite flammable gases, vapors, or dust.
Furthermore, UWB’s performance excels in the physically complex and challenging environments typical of industrial sites. Its ability to penetrate obstacles and resist multipath fading—where signals bounce off surfaces and interfere with each other—ensures reliable and precise location tracking even in areas with dense metal infrastructure. This makes UWB a safer and more effective option for maintaining operational awareness.
An Overview of ATEX and IECEx Compliance
For any equipment to be used in potentially explosive atmospheres, adherence to strict safety standards is mandatory. The two primary global benchmarks are the ATEX Directives for the European Union and the IECEx System for international certification.
Both frameworks are based on the IEC 60079 series of standards and categorize hazardous areas into zones based on the frequency and duration of explosive atmosphere presence.
Hazardous Area Zone Classification and Required Equipment Protection Levels
This classification is vital as it dictates the required level of protection for any electrical equipment, including UWB anchors and tags, deployed within these areas.
Intrinsic Safety: The Core Protection Concept for UWB RTLS
For low-power electronic devices, such as UWB RTLS components, Intrinsic Safety (Ex i) is the most suitable and widely adopted protection method. This design philosophy focuses on preventing explosions by ensuring that the energy, both electrical and thermal, within a circuit is always too low to cause ignition, even under fault conditions.
Principles of Energy Limitation
Intrinsic Safety is achieved by strictly limiting voltage and current. The design must account for worst-case scenarios, such as short circuits or component failures, to ensure that the energy released never reaches the ignition threshold of the specific hazardous substance present.
Hardware Design for Intrinsic Safety
Achieving intrinsic safety certification requires specific engineering practices:
- Current-limiting resistors and voltage-clamping Zener barriers are used to restrict energy flow to safe levels.
- Component spacing and creepage distances on printed circuit boards are increased to prevent arcing.
- Encapsulation of components can be used to isolate them from the hazardous atmosphere.
- Battery selection and protection circuits are crucial in preventing thermal runaway or short circuits.
The level of intrinsic safety is designated as ‘ia’, ‘ib’, or ‘ic’, corresponding to the ability to withstand two, one, or zero faults, respectively, and determining suitability for Zones 0, 1, or 2.
System-Level Architecture for IECEx/ATEX Compliance
Certification applies to the entire system operating within the hazardous area. A compliant UWB RTLS architecture requires a holistic approach.
Data and power lines entering the hazardous area must pass through certified, intrinsically safe galvanic isolators or Zener barriers. These devices are installed in the safe area and act as a firewall, preventing any potentially dangerous energy from a power surge or fault in the safe area from reaching the hazardous zone.
Furthermore, the type and length of cabling are specified to ensure that the cable’s own capacitance and inductance do not store enough energy to become an ignition source.
Deployment and Maintenance of UWB Systems in Hazardous Locations
Proper installation and ongoing maintenance are equally important as the design itself for ensuring continued safety and compliance.
All installation work must be performed by personnel trained and certified to work in hazardous environments.
Key considerations include:
- The use of ATEX/IECEx-certified enclosures, cable glands, and conduit to protect the equipment and wiring.
- Correct system earthing to prevent the buildup of static electricity.
- Adherence to a strict maintenance and inspection schedule as outlined in standards like IEC 60079-17. This includes regular checks for corrosion, damage to enclosures, and the integrity of cable connections.
Conclusion
The path to deploying a certified UWB RTLS in hazardous environments is rigorous, demanding meticulous attention to design, engineering, and regulatory detail.
However, the benefits are substantial. By providing precise, real-time location data for personnel and assets, intrinsically safe UWB systems offer a powerful tool to enhance situational awareness, streamline emergency response, and ultimately prevent accidents.
