Serviceline Industrial Sensors
Phone: 330-486-0001
Fax: 330-405-4710
Serviceline Explosion Protection
Phone: 330-486-0002
Fax: 330-963-5827

Applying DART Fieldbus: Easy to Understand – Easy to Engineer

DART Fieldbus for Zone 1, gas group IIC

The trunk-and-spur topology is accepted and often used. It is the de facto standard in process automation with fieldbus, because it is easy to engineer and easy to manage. A trunk-and-spur topology is made of power supplies and fieldbus couplers. Spurs are certified for your intrinsically safe instrumentation.

Your instrumentation connects to the fieldbus coupler, the DART Segment Protectors. The Segment Protectors are certified for installation in Zone 1 with outputs that are certified intrinsically safe Ex ib IIC. DART protects your plant from the very explosive gasses of group IIC. This means:

  • The same components can be installed throughout your plant, even in different production sites
  • Same spares holding throughout
  • More familiarity for personnel means less training required

The DART Segment Protector provides sufficient power for device connections. Most importantly, it provides the short-circuit protection, which is critical when live maintenance is required on an instrument.

The trunk-and-spur topology with DART Fieldbus: The intrinsically safe High-Power Trunk - ample power for all field devices

Longest intrinsically safe homerun cable

Up to 1000 m of homerun/trunk is permitted with DART Fieldbus. Up to four DART Segment Protectors can be connected to the trunk and provide devices with intrinsically safe power. Spur length is on top with up to 120 m per spur - double the length of FISCO. This is very similar to the High-Power Trunk today.

The table highlights the most important technical attributes of DART Fieldbus. With most attributes influenced by the fieldbus standard (IEC 61158-2), fewer regulations apply for fieldbus in Zone 1 compared to FISCO or the High-Power Trunk.

Technical data for DART Fieldbus

Trunk output power typ. 22 V / 360 mA
Spur output power min. 10.5 V @ 34 mA
Impedance – Cable type: ’A’ 100 Ohm
Trunk cable length, max. 1000 m
Overall cable length, max. (as per IEC 61158-2) 1900 m
Spur cable length, max. (as per IEC 61158-2) 120 m
Entity parameters for instruments Uo, Io 24 V / 250 mA
Trunk length and number of devices all depend very much on the topology and instrumentation you choose.

Planning steps

DART Fieldbus is planned like any other fieldbus segment. Explosion protection almost “comes for free” with very little effort and giving you greatest choice and flexibility on designing fieldbus segments. Planning means to you:

  • Utilize a trunk-and-spur topology with type 'A' cable
  • Plan for the redundant DART Fieldbus Power Supply at one end
  • Use up to 1000 m trunk cable
  • Connect up to four DART Segment Protectors anywhere on the trunk

Only a few limitations apply due to constraints for explosion protection. The rest is “just fieldbus”. The developers of DART Fieldbus have taken great care to engineer the components and explosion protection so that your planning and application of fieldbus in the hazardous area is simple.

DART Fieldbus Products