Product category:
Fieldbus systems, Fibre-optic systems
News Release from: Moore Industries International | Subject: Split architecture
Edited by the Processingtalk Editorial
Team on 24 February 2006
MooreHawke advances IS fieldbus
applications
A new technology from the MooreHawke division of Moore Industries-International is increasing the use of the FF protocol in intrinsically safe areas
A new technology from the MooreHawke division of Moore Industries-International is increasing the use of the fieldbus protocol in intrinsically safe areas Modern digital systems allow more exact control, improving process management and industrial automation
This article was originally published on Processingtalk on 28 Jul 2008 at 8.00am (UK)
Related stories
Measuring boiler and furnace temperatures simply
Protection tubes and flexible sensors make it possible to replace thermocouples in boilers and furnaces, without shutting down the entire process for days or weeks
Dealing with the ATEX Directive requirements in EU
Negotiating the maze of national and international rules and regulations on hazardous area approvals is a minefield, and can extend product development project costs and times considerably
However, in the hazardous environments often found in chemical, pharmaceutical, plastics, and petroleum plants, communication protocols such as Foundation fieldbus initially fell short when intrinsically safe (IS) techniques were required.
The Entity Concept allowed 80 mA through the IS barrier - enough to drive four Foundation fieldbus or Profibus PA devices at an average draw of 20 mA per sensor or transmitter.
Then the FISCO concept, developed in the late 1990s, made more current available in hazardous locations (115 mA in worst-case areas) to comfortably drive five such devices.
However, I and C engineers needed more intrinsically safe PLC and sensor devices to improve process management at their plants.
The split-architecture solution.
The FISCO capacity barrier was recently surpassed by a novel split-architecture design that uses a field-mounted device coupler and an associated power supply with a safe-area interface.
The new technology, developed by engineers at MooreHawke, meets total resistance requirements with a split resistance approach.
A small resistor is used in the IS interface and a larger resistor is placed in the field device coupler.
The small (trunk) resistor "sees" a large current (sum of all devices) but only generates a small voltage drop.
The larger (spur) resistor detects a small current (single device) but also only generates a small voltage drop.
As a result, hazardous area and non-hazardous installations are virtually indistinguishable.
• Moore Industries International: contact details and other news
• Email this article to a colleague
• Register for the free Processingtalk email newsletter
• Processingtalk Home Page
Search the Pro-Talk network of sites
