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| 12/29/2009 4:56 PM | |
Joined: 9/27/2006 Last visit: 12/7/2024 Posts: 12301 Rating:
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Hello Prats; Instrumentation fieldbuses, especially in Ex zones, can be handled by Profibus-PA and Fieldbus Foundation. And yes, cost of cabling will be reduced by using a specific type of cable, from Siemens or Belden (#3076F), which has a 2-core withshield makeup. However, this is not the only cost to take into consideration: every instrument in your network requires its own PA or FF transmitter, and you will need special couplers and junction blocks to connect the instruments. Parameters of the instruments will require a specific software to interface to the network (Siemens' software for PA and HART is called PDM; Endress & Hauser propose Fieldcare). So these hardware and software costs must be taken into account. Also, debugging and troubleshooting the instruments through the network will require a learning curve from the operators and maintenance crew at your plant. This is usually forgotten at the design stage of a project. The advantages of instrumentation Fieldbuses are not negligeable, they provide a lot more diagnostics than standard connections, and they allow preventive maintenance on the instruments. We have used PA for our instrumentation needs for a number of years in our plants, and have found them easy to design, easy to install and troubleshoot,rich in diagnostic features. But reduction of cabling costs cannot be the only consideration. I am attaching a small document from the PTO on Profibus-PA installation; it will show you typical topologies and standard analysis required for setup. Also from the PTO (Profibus.com) here is a System Overview of Profibus-PA: http://www.profibus.com/nc/downloads/downloads/profibus-pa-technology-and-application-system-description/display/ For more information on FF, I suggest you look at Emerson's Plantweb University.(www.plantwebuniversity.com/); you can register for free and access a complete and well-designed course on FF; modules on topolgy and cabling are very explicit. Hope this helps, Daniel Chartier AttachmentInst_Guide_PA_2092_V22_Feb03.pdf (231 Downloads) |
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