Monday, July 2, 2012

 

Foundation Fieldbus Concepts-1

EPC School 2012 Series

I for Instrumentation


Foundation Fieldbus
Fieldbus technology is an accepted industry standard for network
communication for control and instrumentation systems. It is an open network & users of industrial
process control systems are now able to specify proven and standardized
Fieldbus technology for their field instruments. Fieldbuses which convey both communication signal and power on the same pair of wires are among the most popular.

A major influence on the economy of fieldbus installations is the number of field devices which can be connected on a single bus segment and hence to a single controller input/output channel. In particular applications, users may choose to use only a small number of devices on a segment in order to achieve faster scan.

There are different types of fieldbus technologies available in the market today
which may be considered. Some of these are FF H1, Profibus PA, and World
FIP etc.

Of all the technologies, Foundation Fieldbus is preferred for the following reasons:

  1. Well proven for process measurement and control application.
  2.  Different from other technologies as it is not only a communication protocol but also a programming language for building control strategies.
  3. With FF, control can be distributed into field devices.
  4. It improves long term support of technology as fieldbus systems are software and firmware upgradeable.
  5. More efficient commissioning of new installations because the diagnostics identify connection errors after pre-configuration of transmitters.
  6. Increases reliability and availability of instruments of plants by predicting and minimizing end device problems.
  7. Enables integrated automated data collection for plant and maintenance management systems.
  8. Strong diagnostic capabilities. Tracks control valve performance characteristics, transmitter body temperatures, end-device health among other diagnostics. This reduces downtime and production losses. Field calibration of transmitters is not required.
  9. Reduces system hardware costs, cabinet size, cabling, spares inventory.

In view of the above, the transmitters wherever available shall be foundation
fieldbus compatible. Where fieldbus is not possible, smart transmitters with
HART will be considered as per availability. Control valves shall be provided
with FF compatible positioners as preference over conventional pneumatic
positioners and analogue positioners.

The DCS is FF compatible. Lightning & surge protection for fieldbus systems is considered. This will be used to protect electronic circuits and equipment within the fieldbus system and
the associated fieldbus trunk from high voltages and surge currents induced by lightning and other form of transients.

Redundant fieldbus power system is to be used so that the system will become
“hot-swappable” or “hot-standby” meaning that individual power conditioning modules and input power supplies can be replaced without interrupting power or communication on the fieldbus segment.


FIELDBUS WIRING METHODS:

Continued….

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# posted by Rahulkap @ 12:58 PM
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