Marcos peluso emerson english

© 1999 - 2011 Fieldbus Foundation

Fieldbus Foundation General AssemblySão Paulo, Brasil – March, 2012

Marcos PelusoEmerson Process Management

Distinguished Technologist


Why

?

Proven Technology

Reduced Wiring and Installation

Proactive Maintenance

Tighter Control

Greater Reliability


Optimizing Control

Process Variable (%)

40 50 60 70 80 90 100Time (seconds)

56

58

60

66

62

64

Low Temperature Limit

SP


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


Control In The Field Study

Control in the Field:

Analysis of Performance Benefits


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


Control In The DCS with Fieldbus


Control In The DCS with Fieldbus

PI

D

Control Cycle

Macro Cycle


Control In The Field


Control In The Field

PI

D

Macro Cycle


Comparison

CIF enabled

105 AOPID

MessageAI

ms

AIPIDAO

Message


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


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)


Settling Times: Very Fast Process (<1 s)

50

54

58

62

Process output (%)

0 4 8 12 16 20Time (seconds)


55%


Settling Times: Fast Process (2s)

50

54

58

62

Process output (%)

0 4 8 12 16 20Time (seconds)


66%


Settling Times: Medium Process (5s)

50

54

58

62

Process output (%)

0 4 8 12 16 20Time (seconds)


39%


Presence Of Disturbance

Process output (%)

40 50 60 70 80 90 100Time (seconds)


56

58

60

66

62

64


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)


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


• 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%


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


Impact of Tighter Control Loop

Manual

PneumaticAnalogue

Digital

Control limit


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.


Why

?

Proven Technology



Greater Reliability

Tighter Control


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.


Reliability

PSU

PSU


Reliability

Analogue

With CIF

15.9y

48.2y

MTTF


Customer Experience

CIF enabled


Customer Experience

Foundation FieldbusCIF with inherent backup capability

prevented 2 incorrect plant shutdowns, which would have resulted from communication

interruptions.


Why

?

Proven Technology



Greater Reliability

Tighter Control


Thank You! Questions?