Industrial Ethernet has long been well-known and widely used in factory automation. However, process automation in the industry has specific requirements, particularly in cases where some processes may involve potentially explosive environments, making Ethernet unsuitable. These specific requirements include intrinsic safety, online configuration, redundant design (for maximum availability), and long cabling (industrial Ethernet cables are limited to 100 meters in length ). When describing Ethernet technology in the process automation industry, it is crucial to differentiate its availability across different zones.
Excom in Danger Zone 2
Turck offers the Excom fieldbus system, which can be installed in Hazard Zone 2. The Excom system uses Ethernet technology and can acquire signals from Hazard Zone 1 or Hazard Zone 0. To plug or unplug the gateway's Ethernet connector during operation, the gateway must be powered off or a hot work permit must be available. All other components (such as power supplies, gateways, or I/O modules) can be replaced during operation without a hot work permit.
Ethernet technology in Hazard Zone 1
From a technical standpoint, using Ethernet in Hazard Zone 1 is more challenging. For interconnected devices, total power must be kept within safe limits. Many automation companies are currently looking to overcome these hurdles and develop intrinsically safe two-wire Ethernet standards, using the same line for communication and power. Future standards typically refer to Advanced Physical Layer ( APL ). However, these developments are not yet suitable for widespread industrial applications in Hazard Zone 1 ( as of March 2020 ). In the future, APL should enable Ethernet connectivity to field devices. However, for cost reasons, even after APL is established, classic 4-20 mA technologies and fieldbus systems will continue to coexist.
