Fieldbus systems are being used in ever greater numbers in the area of process automation for the following reasons:
The most popular configuration connecting field instrumentation to the DCS with fieldbus today is the trunk-and-spur topology. A main line (the trunk) carries energy and data into the field. The energy and data is distributed with one device each connected to a branch line (the spur)
The fieldbus couplers are mounted in the field near the field device. Spur lines can be up to 120 m in length. Multiple fieldbus couplers are often combined in one preconfigured housing certified for installation in the Ex-Zone.
The fieldbus distribution is selectable for the configuration and protection concept of your choice.
Pepperl+Fuchs designed the High-Power Trunk Concept to overcome power limitations for explosion protection. We were the first to bring energy-limiting fieldbus couplers to process automation.
In principle, the trunk line transmits power of up to 31 V and 500 mA, not limited for explosion protection purposes. The fieldbus coupler - either a FieldBarrier or Segment Protector - is installed near the field instrumentation. Thus, the maximum cable length can be reached, and many devices can be connected, while simplifying verification of explosion protection. Installation and maintenance crews enjoy the benefits as field devices can be installed or maintained while the plant is in operation - all of this occurs without a hot work permit.
For Ex ic, the FieldConnex High-density Power Hubs (MBHD-FB*) and R2 Segment Protectors (R2-SP-N*) enable an economic and easy way of Ex ic explosion protection with a choice of voltages. The Power Hub limits the voltage in selected power supply modules, and the R2 Segment Protector limits the current. Both conform to the design specifications and carry certificates. Users have the choice to validate the explosion protection according to FISCO Ex ic or Entity Ex ic.