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Marcos Peluso fo Emerson General Assembly Presentation
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© 1999 - 2011 Fieldbus Foundation
Fieldbus Foundation General AssemblySão Paulo, Brasil – March, 2012
Marcos PelusoEmerson Process Management
Distinguished Technologist
© 1999 - 2011 Fieldbus Foundation
Why
?
Proven Technology
Reduced Wiring and Installation
Proactive Maintenance
Tighter Control
Greater Reliability
© 1999 - 2011 Fieldbus Foundation
Optimizing Control
Process Variable (%)
40 50 60 70 80 90 100Time (seconds)
56
58
60
66
62
64
Low Temperature Limit
SP
© 1999 - 2011 Fieldbus Foundation
Optimizing Control
Process Variable (%)
40 50 60 70 80 90 100Time (seconds)
56
58
60
66
62
64
Low Temperature Limit
SP
© 1999 - 2011 Fieldbus Foundation 5
CostSavings
© 1999 - 2011 Fieldbus Foundation
Control In The Field Study
Control in the Field:
Analysis of Performance Benefits
© 1999 - 2011 Fieldbus Foundation
The report from the University of Strathclyde and ISC is divided in two parts:
1. Comparing Control in the Controller with Control in the Field when Fieldbus is used in both cases.
2. Comparing Control in the DCS with a 4-20 mA with Fieldbus Control in the Field
Comparison
© 1999 - 2011 Fieldbus Foundation
Control In The DCS with Fieldbus
© 1999 - 2011 Fieldbus Foundation
Control In The DCS with Fieldbus
PI
D
Control Cycle
Macro Cycle
© 1999 - 2011 Fieldbus Foundation
Control In The Field
© 1999 - 2011 Fieldbus Foundation
Control In The Field
PI
D
Macro Cycle
© 1999 - 2011 Fieldbus Foundation
Comparison
CIF enabled
105 AOPID
MessageAI
ms
AIPIDAO
Message
© 1999 - 2011 Fieldbus Foundation
Comparison
CIF enabled
No CIF
125
AOPID
MesssageAI
AOMessage
PIDMessage
AI
105
ms
~
250 AOMessage
MessageAI
375 AOMessage
MessageAI
625AO
Message
ControlCycle
500 ms
~~~~
PID
© 1999 - 2011 Fieldbus Foundation
Settling Times: Fastest Process (<500 ms)
50
54
58
62
Process output (%)
0 4 8 12 16 20Time (seconds)
60%
Setpoint Case 1 - CIFCase 3 - Control in DCS (async)
© 1999 - 2011 Fieldbus Foundation
Settling Times: Very Fast Process (<1 s)
50
54
58
62
Process output (%)
0 4 8 12 16 20Time (seconds)
Setpoint Case 1 - CIFCase 3 - Control in DCS (async)
55%
© 1999 - 2011 Fieldbus Foundation
Settling Times: Fast Process (2s)
50
54
58
62
Process output (%)
0 4 8 12 16 20Time (seconds)
Setpoint Case 1 - CIFCase 3 - Control in DCS (async)
66%
© 1999 - 2011 Fieldbus Foundation
Settling Times: Medium Process (5s)
50
54
58
62
Process output (%)
0 4 8 12 16 20Time (seconds)
Setpoint Case 1 - CIFCase 3 - Control in DCS (async)
39%
© 1999 - 2011 Fieldbus Foundation
Presence Of Disturbance
Process output (%)
40 50 60 70 80 90 100Time (seconds)
Setpoint Case 1 - CIFCase 3 - Control in DCS (async)
56
58
60
66
62
64
© 1999 - 2011 Fieldbus Foundation
Presence Of Disturbance: Different Processes
Fastest1.811
2.132
0.517
0.82
0.642
1.058
0.231
0.53
65% better
50% better
55% better
35% better
Very Fast
Fast
Medium
Setpoint CIF1.811 control in
DCS (async)
© 1999 - 2011 Fieldbus Foundation
Simulation results demonstrated:• Control in the Field with Fieldbus offers 5 to 30%
improvement than control with 4-20 mA.• Improvement depends on process response
time and dead time. • Faster processes (Flow, Pressure) benefit more
than slow processes (some Temperature loops)• More improvement is observed in PI or PID
control. Very small improvement for P or PD control.
• Better improvement observed for fast disturbances
Control in the DCS with 4-20 mA
© 1999 - 2011 Fieldbus Foundation
• For very fast loops, the improvement in variability is close to 30%
• For a 10 s response time, improvement varies from 5 to 15%
• For 50 s response time, improvement varies from 1.5 to 4.8 %
Control Cycle Stochastic Disturbance
250 ms 5.5%
500 ms 8.5%
1000 ms 15%
© 1999 - 2011 Fieldbus Foundation
Main reasons for better control:• Deterministic Control
• In Control in the Field, blocks and messages follow strict schedule
• Time based control expects variables and actions happening at a fixed period
• In the DCS, IO cards are not synchronized with the Controller, time between samples vary.
• Reduced Latency implies lower Dead Time. Control in the Field offers lower latency
• Dead Time is deadly for control
Controllability = . Process Time Constant
Dead Time
© 1999 - 2011 Fieldbus Foundation
Impact of Tighter Control Loop
Manual
PneumaticAnalogue
Digital
Control limit
© 1999 - 2011 Fieldbus Foundation
Recommended For Fast Loop Response
Control in the field usingFoundation fieldbus technology is recommended by SGSI for simple and cascading loops, not for
complex loops.
Major benefits identified by SGSI are reduced process controller loading, reduced network traffic enabling more loops per segment, as
well as very fast loop response.
© 1999 - 2011 Fieldbus Foundation
Why
?
Proven Technology
Reduced Wiring and Installation
Proactive Maintenance
Greater Reliability
Tighter Control
© 1999 - 2011 Fieldbus Foundation
The Need For Reliability
ARC Insight
10th June 2010
The global process industry loses $20billion, or five percent of annual production, due
to unscheduled downtime and poor quality.
ARC estimates that almost 80 percent of these losses are preventable, with 40 percent largely
due to operator error.
© 1999 - 2011 Fieldbus Foundation
Reliability
PSU
PSU
© 1999 - 2011 Fieldbus Foundation
Reliability
Analogue
With CIF
15.9y
48.2y
MTTF
© 1999 - 2011 Fieldbus Foundation
Customer Experience
CIF enabled
© 1999 - 2011 Fieldbus Foundation
Customer Experience
Foundation FieldbusCIF with inherent backup capability
prevented 2 incorrect plant shutdowns, which would have resulted from communication
interruptions.
© 1999 - 2011 Fieldbus Foundation
Why
?
Proven Technology
Reduced Wiring and Installation
Proactive Maintenance
Greater Reliability
Tighter Control
© 1999 - 2011 Fieldbus Foundation
Thank You! Questions?
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