Operation Stations in a Distributed Control System

4/7/2009
4/7/2009 Prepared by Engineer Ahmed
Prepared by Engineer Ahmed Aboulmagd
Aboulmagd
Operation Stations
Operation Stations
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Operations Work Centers
Work stations essential functions:
Work stations essential functions:
Monitor plant operations
Monitor plant operations
Call attention to process upsets and alarms
Call attention to process upsets and alarms
Provide a facility for taking corrective action when necessary
Provide a facility for taking corrective action when necessary
Present various trends occurring within the process
Present various trends occurring within the process
Interact with plant personnel performing functions outside the
Interact with plant personnel performing functions outside the
scope of the control system
scope of the control system
Maintain good records on plant operating characteristics
Maintain good records on plant operating characteristics
Ensure that the control system is functioning properly
Ensure that the control system is functioning properly
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Work stations typically contain several video displays and
Work stations typically contain several video displays and
supplemented by a variety of information devices, including:
supplemented by a variety of information devices, including:
Alarm printers
Alarm printers
High speed report writers
High speed report writers
Video copiers
Video copiers
User
User-
-assignable multipin trend recorders
assignable multipin trend recorders
Annunciator lamps
Annunciator lamps
Audible signals (messages)
Audible signals (messages)
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Process display hierarchy
Process display hierarchy
Main challenge is to provide mechanisms for monitoring
Main challenge is to provide mechanisms for monitoring
hundreds (sometimes thousands) of process parameters in an
hundreds (sometimes thousands) of process parameters in an
effective manner with a very limited display area
effective manner with a very limited display area
Two available approaches:
Two available approaches:

 Panelboard emulation
Panelboard emulation

 Process graphic representations
Process graphic representations
Most commercially available systems include elements of
Most commercially available systems include elements of
both approaches
both approaches
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Process display
Process display
hierarchy
hierarchy
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Plant, area, unit &
Plant, area, unit &
sub
sub-
-unit graphics
unit graphics
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Plant, area, unit & sub
Plant, area, unit & sub-
-unit graphics
unit graphics
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Process display hierarchy navigation
There are several techniques for moving among these displays:
There are several techniques for moving among these displays:

 Keyboard
Keyboard

 Dedicated function keys
Dedicated function keys

 Group numbering addressing
Group numbering addressing

 Tag referenced addressing
Tag referenced addressing

 Display
Display-
-dependent function keys
dependent function keys

 Cursor positioning, using dedicated directional keys
Cursor positioning, using dedicated directional keys
Other Techniques
Other Techniques

 Light pen
Light pen

 Mouse (auxiliary cursor positioning technique)
Mouse (auxiliary cursor positioning technique)

 Touch
Touch-
-sensitive screens
sensitive screens

 Joystick (pan and zoom)
Joystick (pan and zoom)

 Voice actuation (a possibility for the future)
Voice actuation (a possibility for the future)
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The acceptable approaches include a number of common
The acceptable approaches include a number of common
characteristics:
characteristics:

 Simplicity of operation
Simplicity of operation

 Reinforcement of relatively few patterns of use
Reinforcement of relatively few patterns of use

 Fault tolerance (minimization of the occurrence of inadvertent
Fault tolerance (minimization of the occurrence of inadvertent
actions; ease of recovery from improper actions)
actions; ease of recovery from improper actions)

 Reliable design requiring relatively little maintenance
Reliable design requiring relatively little maintenance
The most popular current approach employs a self
The most popular current approach employs a self-
-prompting
prompting
or various function keyboards with keys which relate directly
or various function keyboards with keys which relate directly
to the display on the video screen.
to the display on the video screen.
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Example of a
Example of a
variable function
variable function
keyboard
keyboard
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Typical Group Display
Typical Group Display
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Example of control group display
Example of control group display
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Typical Detail Display
Typical Detail Display
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Typical Overview
Typical Overview
Display
Display
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List Display
List Display
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Typical Graphic Display
Typical Graphic Display
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Example of graphic display
Example of graphic display
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Typical Trend Display
Typical Trend Display
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Typical trend display
Typical trend display
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Typical controller tuning display
Typical controller tuning display
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Typical operator help message display
Typical operator help message display
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Classification of alarms
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Process alarms
Process alarms

 Indication that represents an abnormal condition in the process.
Indication that represents an abnormal condition in the process. It
It
may be unhealthy condition of the drive, variation in the parame
may be unhealthy condition of the drive, variation in the parameter
ter
above or below the set level, starting or tripping of the proces
above or below the set level, starting or tripping of the process.
s.
System alarms
System alarms

 Indication that represents an abnormal condition in the system.
Indication that represents an abnormal condition in the system. It
It
may be the node going offline, stopping of the control language,
may be the node going offline, stopping of the control language,
failure of the peripherals etc.
failure of the peripherals etc.
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High priority alarms
High priority alarms

 These come next to the emergency and call for attention of
These come next to the emergency and call for attention of
the operator.
the operator.
Low priority alarms
Low priority alarms

 These are lowest in priority and may just be used for passing
These are lowest in priority and may just be used for passing
out the information to the operator so that he becomes alert in
out the information to the operator so that he becomes alert in
time.
time.
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Operator Interface Design
Operator Interface Design
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Initial
Initial
planning
planning
sheet
sheet
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Operator
Operator-
-
Interface
Interface
Geometry
Geometry
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Glare from reflected ambient lighting
Glare from reflected ambient lighting
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Alphanumeric Displays
Alphanumeric Displays
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Keyboards
Keyboards
Keyboard with standard QWERTY layout.
Keyboard with standard QWERTY layout.
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Keyboards
Keyboards
Dvorak simplified keyboard input
Dvorak simplified keyboard input
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Typical operator keyboard
TDC 3000
TDC 3000
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INFI 90
INFI 90
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Centum CS
Centum CS
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Basic DIN standard dimensions and
Basic DIN standard dimensions and
angular restrictions
angular restrictions
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Panelboard
Panelboard
Concept
Concept
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CRT
CRT-
-based
based
panels Concepts
panels Concepts
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DCS Operator Interface
DCS Operator Interface
Early DCS operator interfaces
were expensive to install
and maintain since the
physical components were
often custom design and
construction.
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Typical control loop
Typical control loop
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