Comparing
New Generation
Digital
PAS with Traditional DCS
More
and more global companies are choosing to adopt a fundamental change
in the way they look at automation, explains Shekhar Shirwalkar
Automation
A Sea Change is on the Cards: An Overview
Technology,
in many ways is playing a critical role in today’s business strategies.
Various arms of technology have been converging, giving rise to integrated
solutions that benefit the industry at various levels. The size of the
newer equipment and systems is becoming smaller while the features and
capabilities are increasing. There is also a noticeable trend towards
more open, flexible and scalable technologies both in terms of hardware
and software. Overall, the industrial world is experiencing a sea change
in terms of global market dynamics and process control and automation
technology is no exception.
Looking
at the challenges faced by process industries, and the powerful developments
that have materialised on the process instrumentation technology front;
there is no better time to migrate to the new automation technologies.
More and more global companies are choosing to adopt a fundamental change
in the way they look at automation.
Till
the last decade, automation was seen as a tool used for performing critical
‘measurement and control’ operations as prescribed by the process licenses.
The advancements in electronics and software technologies gave rise
to a family of intelligent field devices that are capable of generating
a wealth of vital information, about themselves and the process they
are measuring. Unfortunately though, on the control and automation architecture
front, very little thought was given to make best use of the information
generated by these intelligent devices. The conventional architecture,
which is characterised by close-ended proprietary technologies and DCS-centric
operations, has been the biggest hurdle in the growth of automation
market. This not only restricts the free flow and availability of information
across the plant, but also highly under-utilises the capabilities of
intelligent devices.
In
India, the DCS concept started picking up in the last 20 years or so.
Obviously, most of the DCS in operation in India are based on the technology,
which is at least 10-12 years old. A recent study showed that the use
of an outdated DCS is preventing many manufacturers around the world
from achieving efficiency and productivity benefits possible from newer
technologies. So where do you go from here?
With
the advent of digital automation technologies like fieldbus and convergence
of information technology with process control and automation, the older
legacy DCS is bound to get replaced with the new generation PAS (Plant
Automation System). These systems have not only broken the size and
cost barrier of a traditional DCS but also offer more capabilities,
scalability, flexibility and connectivity with other components in an
integrated business environment.
This
article compares in today’s context how these new generation PAS operating
in a digital open field-centric automation architecture offers substantial
benefits over the conventional DCS approach. The FOUNDATION fieldbus
technology has been chosen to represent the digital bus technology because
of its proven success in the process automation applications. The illustrations
are based on a real case study of one of the early installations of
fieldbus in North Alaska.
There
is substantial hardware installation savings associated with a new generation
FOUNDATION fieldbus system as compared to a traditional DCS installation.
An engineering contractor analyzed the results of a FOUNDATION fieldbus
installation for an Alaskan North Slope oil producer.
Introduction
The
PAS FOUNDATION fieldbus technology is a digital communications network
that improves plant performance. Using asset management software (AMS),
this PAS extracts information contained in FOUNDATION fieldbus devices
and shares this process variable information with the control system.
AMS is a new component, which has not been the part of a traditional
DCS system. The PAS with FOUNDATION fieldbus uses the OLE for Process
Control (OPC) standard to ensure that configuration, calibration, status,
performance and health of the devices are accessible plant-wide. Predictive
maintenance capabilities, improved process control and increased dissemination
of information are benefits not found in a traditional DCS system.
All
installations are unique. To get an accurate comparison of a FOUNDATION
fieldbus installation and a traditional DCS installation, we will compare
a 16-device installation using a PAS with FOUNDATION fieldbus and a
DCS. It will show how I/O terminations decrease by 75% when PAS with
FOUNDATION fieldbus technology is used instead of a traditional DCS.
It will also show how the number of I/O cards, home run wiring, number
of transmitters, and instrument control room panel space decreases substantially
when a PAS with FOUNDATION fieldbus is installed instead of a traditional
DCS....
....contd
