Performance Controler IM302

7/23/2019 Performance Controler IM302

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U

4725 121st Str

Des Moines, Iowa 50323, U.S

Phone: (515) 270-0

Fax: (515) 270-1

GLOBAL

SUPPLIERS

OF

TURBINE

AND

COMPRESSOR

CONTROL

SYSTEMS

Web: www.cccglobal.c

A/D

RAM

PID

ID

F

IM302

Series 3 Plus

Performance Controller

for Axial and CentrifugalCompressors

Publication IM302 (6.0.1)

Product Revision: 956-001

February 2001
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1987-1999, Compressor Controls Corporation. All rights reserved.

This manual is for the use of Compressor Controls Corporation and isnot to be reproduced without written permission.

The impeller and TTC logos, Total Train Control, TTC, Recycle Trip,Safety On, Air Miser, TrainView, and WOIS are registered trademarks;

and the Series 5 logo, Reliant, Vanguard, TrainTools, TrainWare,SureLink, Guardian, and COMMAND are trademarks of CompressorControls Corporation. Other product and company names used herein

are trademarks or registered trademarks of their respective holders.

The control methods and products discussed in this manual may be

covered by one or more of the following patents, which have beengranted to Compressor Controls Corporation by the United StatesPatent and Trademark Office:

4,486,142 4,494,006 4,640,665 4,949,2765,347,467 5,508,943 5,599,161 5,609,465

5,622,042 5,699,267 5,743,715 5,752,3785,879,133 5,908,462 5,951,240 5,967,742

6,116,258

Many of these methods have also been patented in other countries,and additional patent applications are pending.

The purpose of this manual is only to describe the configuration and

use of the described products. It is not sufficiently detailed to enableoutside parties to duplicate or simulate their operation.

The completeness and accuracy of this document is not guaranteed,and nothing herein should be construed as a warranty or guarantee,express or implied, regarding the use or applicability of the described

products. CCC reserves the right to alter the designs or specificationsof its products at any time and without notice.


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Series 3 Plus Performance Controller

3

IM302 (6.0.1)

Document Scope

This manual tells how to configure, tune, and operate a Series 3 Plus PerformanceController. It does not tell how to install or maintain it (see the Series 3 Plus Hard-ware Reference

[IM300/H]), nor how to program a host computer or DCS to use its

Modbus interface (see the Series 3 Plus Modbus Reference

[IM300/M]).Chapter 1 summarizes this controllers applications and features.

Chapter 2 describes the operation of the Performance Controller.

Chapter 3 tells how to configure the analog and discrete inputs and outputsand serial communication ports.

Chapter 4 tells how the Performance Controller calculates its performancecontrol variables and describes its fallback strategies.

Chapter 5 tells how to configure the PID loops and explains how the perfor-mance control response is selected from their actions.

Chapter 6 tells how to coordinate a Performance Controllers actions with othercontrollers regulating the same compressor.

Chapter 7 tells how to configure the compressor load-sharing algorithms.

Chapter 8 tells how the intended valve position and actuator control signal arecalculated from the performance control response.

Chapter 9 tells how to set up the Performance Controllers automatic sequenc-ing, manual override, and redundant control features.

Appendix A describes each Performance Controller configuration parameter.

Appendix B describes the controller test procedures that can be executed fromthe Engineering Panel.

Glossary/Index lists, summarizes, and directs you to the manual sections that pro-vide more complete information on various topics.

Finally, the following supporting documents are included at the back of this manual:

DS302/M lists this controllers Modbus coils, discrete bits, and registers.

DS302/O describes the controllers Front-Panel operator interface.

DS302/V describes the changes in each standard release of the PerformanceController software.

FM302/C lists the configuration and tuning parameters by key sequence,organized by data group and page.

FM302/L lists the configuration and tuning parameters by name, groupedaccording to the associated controller feature.
http://im300h.pdf/http://im300h.pdf/http://im300h.pdf/http://im300m.pdf/http://im300m.pdf/http://../DataSheets/DS302M.pdfhttp://../DataSheets/DS302M.pdfhttp://../DataSheets/DS302O.pdfhttp://../DataSheets/DS302V.pdfhttp://../DataSheets/DS302V.pdfhttp://../DataSheets/DS302V.pdfhttp://../Forms/FM302C.pdfhttp://../Forms/FM302L.pdfhttp://../DataSheets/DS302V.pdfhttp://../DataSheets/DS302V.pdfhttp://../DataSheets/DS302M.pdfhttp://../DataSheets/DS302V.pdfhttp://../DataSheets/DS302M.pdfhttp://im300m.pdf/http://im300h.pdf/http://im300h.pdf/http://../Forms/FM302L.pdfhttp://../Forms/FM302C.pdfhttp://../DataSheets/DS302O.pdf


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4

Contents

February 2001

The document title appears in the header of each odd-numberedpage, while the chapter or appendix title appears in the header ofeven-numbered pages. Odd-page footers list the document number

and revision level [IM302 (6.0.1)], while even-page footers providethe publication date (February 2001).

Acronyms are defined in the sections of this manual that discuss thecorresponding subjects, by placing them in parentheses followingthe spelled-out terms they represent. As an example, a three-letteracronym (TLA) is a way to represent a three-word subject by com-bining and capitalizing the initial letters of those three words. Mostare also listed under Symbols and Acronymson page 11.

Cross-references to other documents specify a section and chapter,while cross-references between chapters of this document specify apage number. References that do not specify a location are internalto the chapter in which they appear. In computerized versions of thismanual, all such references are hot-linked to their target locationsand appear in green. Entries in the tables of contents, illustrationand table lists, and index are also hot-linked but are not green.

The Titles

of other documents are italicized. In cross-references,double quotation marks are used to delineate section headings (forexample, see Document Scopeon page 3).

Attention may be drawn to information of special importance byusing this text stylingor one of the following structures:

Note:

Notes contain important information that needs to be emphasized.

Caution:

Cautions contain instructions that, if not followed, could lead to irre-versible damage to equipment.

Warning!

Warnings contain instructions that, if not followed, could leadto personal injury.

Document Conventions


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Table of Contents

Document Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Document Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Table of Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Symbols and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Chapter 1 Overview

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Major Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Capacity Control Variable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Set Points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Capacity Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Recycle Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Load Sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Fallback Strategies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Loop Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Speed Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Automatic Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Automatic or Manual Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Redundant Controller Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Hardware Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Analog and Discrete I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Control Element Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Serial Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Configuration and Tuning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Chapter 2 Operation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Operator Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Continuous Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Stand-Alone Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Control Element Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Alternate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Capacity Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Station Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Automatic Suspension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Load-Sharing Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Primary Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Load Balancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Load-Sharing Fallback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Sequencing Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Stop/Idle State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Load-Sharing Startups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35


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Manual Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36Initiating Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37Restoring Automatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Manual Override . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Fault Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Tracking States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Speed or Output Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41Redundant Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Chapter 3 Input/Output Features

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Hardware Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43Disabling Input Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Analog Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44Analog-to-Digital Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45Transmitter Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45Signal Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45Process Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Measured Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46Analog Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Split Range Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Output Loopback Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49Valve Position Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Discrete Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51Discrete Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Fault Relays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52External Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Serial Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55ID Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Serial Communication Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . .56Serial Communication Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56Modbus Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

Chapter 4 Calculated Variables

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Performance Control Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59Capacity Control Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Single Input Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Load Balancing and Cold-Recycle Control . . . . . . . . . . . . . . . . .61Mass Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61Compression Ratio Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Fallback Control Variable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Limiting Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Pressure Override Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65PV and SP Readouts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Software Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

Fallback Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67Capacity Control Fallback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67Limiting Control Fallback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68Pressure and Temperature Fallbacks . . . . . . . . . . . . . . . . . . . . . . .68


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Remote Set Point Fallback. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68Load-Sharing Fallback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Chapter 5 Performance Control

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

General PID Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69Dead Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Loop Direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70Set Point Ramping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71Capacity Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

CV1 Set Point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72Limiting Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Alternate Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Performance Control Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Chapter 6 Coordinated Control

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Loop Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Decoupling Gain Sign Conventions . . . . . . . . . . . . . . . . . . . . . . . . 78

Antisurge from Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Performance from Antisurge. . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Performance from Performance . . . . . . . . . . . . . . . . . . . . . . . . . 79

Recycle Limiting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Auxiliary Limiting Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Pressure Override Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Pressure Override Predictor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Speed Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Serial Speed Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Analog Speed Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Chapter 7 Load-Sharing Control

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Load Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Primary Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Station Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Load-Sharing Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Antisurge Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Unit Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Load Balancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Parallel Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92Series Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Load Limit Condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95Load-Sharing Fallback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Parallel Recycling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97Recycle Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97Cold-Recycle Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Cold-Recycle Antisurge Control . . . . . . . . . . . . . . . . . . . . . . . . . 99Cold-Recycle Performance Control . . . . . . . . . . . . . . . . . . . . . . 99

Air Miser Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Calculated Variable Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Measured Total Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102Available Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103


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Summed Total Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104Total Drive Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104System Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104

Capacity Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105Start Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105Stop Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

Extraction Load Sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106

Chapter 8 Output Variables

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

Intended Valve Position. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107Output Clamps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108Valve Flow Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110

Actuator Control Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111Valve Dead Band Compensation. . . . . . . . . . . . . . . . . . . . . . . . . .111Display Output Reverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Chapter 9 States and Transitions

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113

Automatic Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113

Operating State Request Signals . . . . . . . . . . . . . . . . . . . . . . . . .114Check Valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115Start-Up Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116Shut-Down Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117Coordinated Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117

Manual Override . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119Alternate Parameter Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119Redundant Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120

Switching Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120Alternate Control Strategies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120

Appendix A Configuration Parameters

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121

Appendix B Controller Test Sequences

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .155

Glossary/Index

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165


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Symbols and Acronyms

A series load-sharing domain selection variable

ACS Actuator Control Signal

AD1 to AD8 Analog-to-Digital variables

CCC Compressor Controls Corporation

CH1 to CH8 analog input CHannels

CPU Central Processing Unit

CR

D

Derivative Control Response

CR

I

accumulated Integral Control Response

CR

I

Integral Control Response

CR

LD

Loop-Decoupling Control Response

CR

P

Proportional Control ResponseCR

PC

Primary Capacity Control Response

CRC Cyclic Redundancy Checksum

CRIC Cold-Recycle (flow) Indicating Controller

CR1 to CR5 Control Relays (discrete outputs)

CSP Computer Set Point

CV Control Variable or Check Valve

CV

b

load-balancing Control Variable

CV0 pressure override Control Variable

CV1 capacity Control Variable

CV2 higher priority limiting Control Variable

CV3 lower priority limiting Control Variable

DCS Distributed Control System

DEV antisurge control DEViation

DEV' parallel compressor load-balancing variable

DO1 to DO5 Discrete Outputs (control relays)DPT Differential Pressure Transmitter

e error (control loop deviation)

EEPROM Electrically Erasable Programmable Read-Only Memory

Eff system Efficiency calculated variable

ESD Emergency ShutDown

fA Application function


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FIC Flow Indicating Controller

FIOM Field Input/Output Module

FCV Fallback Control Variable

FT Flow Transmitter

FY Flow TransducerGTIC Gas Turbine (fuel) Indicating Controller

I/O Input and Output circuits

I/P Current-to-Pneumatic signal converter

IT Current Transmitter

IFR Intended Flow Rate

IVP Intended Valve Position

J power

L series compressor load-balancing variable

LD Loop Decoupling

LED Light Emitting Diode

LodP Loaded Primary condition

LodS Loaded Secondary condition

LS Load-Sharing

LSIC Load-Sharing Indicating Controller (slave Performance Controller)

LSP Local Set Point

M Molecular weight, occasionally Motor

MaxQ Available Mass Flow

N rotational speed (generally, the Number of revolutions per unit time)

NO/NC Normally-Open/Normally-Closed

OP Operating Point

OutF Output Failure

OUT1 analog OUTput 1

OUT2 analog OUTput 2P Pressure

P

c

Pressure rise across a Compressor

P

c

Compensating Pressure for mass flows

P

d

Discharge Pressure

P

d,a

absolute Discharge Pressure


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P

d,g

gauge Discharge Pressure

P

dh

Discharge Header Pressure

P

o

Pressure drop across an Orifice plate (flow measurement)

P

o,1

main flow measurement

P

o,2

second or sidestream flow measurementP

s

Suction Pressure

PCB Printed Circuit Board

PCR Performance Control Response

PI Proportional-Integral

PIC Pressure Indicating Controller

PID Proportional-Integral-Derivative

P&ID Piping and Instrumentation Diagram

POC Pressure Override Control

POP Pressure Override Predictor

POV Pressure Override Variable

Power total drive Power

psi pounds per square inch

PT Pressure Transmitter

PV1 to PV8 Process Variables

Q volumetric flow

q

s

reduced volumetric flow in Suction (preferred)

Q

s

volumetric flow in Suction

Q

s,red

reduced volumetric flow in Suction (alternate)

RAM Random Access Memory

R

c

Compression Ratio

RCS Redundant Control Selector

RFR Required Flow Rate

rpm revolutions per minuteRSP Remote Set Point

RT Recycle Trip

R

T

Temperature Ratio

RTL Recycle Trip Line

S proximity to the surge control line


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Figure 1-3 Compressor with multiple feeds and control elements

Because it is far more efficient to regulate throughput by adjustingthe compressor speed, the Performance Controller is often used tomanipulate the set point of the drivers speed governor (if that is a

turbine, integrated control can be obtained by combining the Perfor-mance Controller with a Series 3 Plus Speed or Fuel Controller). Ifthere are two throttling elements, a single Performance Controllercan manipulate both for increased efficiency. The system shown inFigure 1-3uses analog signals to manipulate inlet guide vanes anda speed governor. The system in Figure 1-4uses serial communica-tion with Series 3 Plus Fuel Controllers to regulate compressorsdriven by gas turbines, while the one in Figure 1-5uses Series 3Plus Speed Controllers to regulate steam-turbine-driven units.

In addition to single-input variables like the discharge pressure, the

Performance Controller can be configured to regulate the compres-sion ratio or a pressure- and temperature-compensated mass flow(also known as standard volumetric flow). If the total flow can not bemeasured because there are multiple feed and discharge streams,two flow measurements can be combined (see Figure 1-3).

FT TT PT

FT

FY

PIC Performance ControllerSIC Speed Controller

FT TT TTPT PT

UICPort 1

FY

TT PT

PIC

FY

SIC

UIC Antisurge Controller

N

SP


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Major Features This software revision (956-001) offers the following features: the Capacity Control Variablecan be any analog input (usually

a pressure or flow measurement), a temperature and pressure-compensated mass flow rate, the compression ratio, or a load-sharing variable based on proximity to surge

bumpless switching between remote and local Set Points two Capacity Limitingloops that can override the capacity con-

trol loop to maintain the analog inputs for any two processvariables (such as drive-motor current or fluid temperature)within safe or acceptable ranges

Recycle Limitingfeatures that use a companion Antisurge Con-troller to help regulate throughput or a pressure overridevariable.

Load Sharingfor compressors operating in series or in parallelor for single-extraction steam turbines

Fallback Strategiesthat can provide continued control whenotherwise required analog or serial communication inputs fail

Loop Decouplingthat minimizes adverse interactions between acompressors capacity and antisurge control loops

Speed Trackingfeatures that provide coordinated control ofturbine-driven compressors

Automatic Sequencingof compressor startups and shutdowns

Automatic or Manual Operationfrom the Front Panel or a hostcomputer or control system

Redundant Controller Trackingthat allows one PerformanceController to serve as an on-line backup to another

Basic or Extended I/O Hardware Configurations

Analog and Discrete I/Oports that can be assigned functionsappropriate to each application

Control Element Featuresthat adapt the analog output to virtu-ally any final control element, allow both outputs to be used tocontrol separate control elements, and test its accuracy

Serial Communicationwith companion Series 3 Plus Control-lers, operator workstations, and Modbus host systems

Configuration and Tuningfrom either the Engineering Panel(from which three alternate parameter sets can be stored andrecalled) or from a computer workstation

Please refer to the Series 3 Plus Performance Controller RevisionHistory[DS302/V]for information about previous revisions.
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Figure 1-7 Performance Controller functional diagram

PI Algorithm

or

Display OutputReverse

Valve DeadBand Compensation

OUT Readout

IFR

IVP

e1

Loop Reverse 1

CV1

SP1

Application Function

Dead Zone

Output Clamps Speed TrackingManual

PCR

or

Limiting Control Response Selection

PID Algorithm

PID2PID1 PID3

e2

CV2

Disable/High/Low

Loop Decoupling

e3

CV3

Disable/High/Low

Valve Flow Characterizer

e0

Input Select

Loop Reverse 0

POV (CV0)

SP2

Analog Inputs

Loop Reverse 3Loop Reverse 2

Input Select Input Select

SP3orLSP

RSP

POC Predictor

I0P0

Relative POC SP

SP0

to Antisurge Controllers

OUT2OUT1

or Split Range Output

ACS

Primary Capacity

Control

Control Signal

Station Controller

PIDs & RTs

Interacting Loop


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Controller can regulate its compressor as a stand-alone machine(see Load-Sharing Fallbackon page 96).

When two or more single-extraction steam turbines are connectedto the same header, their total load can be distributed by using aPerformance Controller to calculate the flow set points of theirExtraction Controllers (see Extraction Load Sharingon page 106).

FallbackStrategies

If analog input or serial communication failures preclude calculationor measurement of a capacity control or limiting variable or set point,the controller can employ default values or hold the performancecontrol signal constant (see Fallback Strategieson page 67). In amultiple compressor application, it can also switch to an alternatecontrol loop (see Load-Sharing Fallbackon page 96).

Loop Decoupling The controller can counter the potentially destabilizing effects thatcan result from interactions between the various control loops regu-

lating a single compressor by adjusting its control response inresponse to changes in the output signals of companion controllers(see Loop Decouplingon page 77).

Speed Tracking If the performance control signal is used as the remote set point of aturbine or motor speed governor, the capacity control and limitingloops can be configured to avoid integral windup when that governoris ignoring its remote set point, and to bumplessly restore cascadespeed control when the governor resumes using its remote set point(see Speed Trackingon page 83):

If the governor is a Series 3 Plus Speed or Fuel Controller,speed tracking can be implemented via Port 1 serialcommunications.

Otherwise, speed tracking can be implemented using analogand discrete signals.

AutomaticSequencing

The controller can be set up to automatically load and idle the com-pressor in response to user-specified analog, discrete, and serialcommunication signals (see Automatic Sequenceson page 113):

The start-up sequence loads the compressor by increasing the

performance control response until specified throttle control ele-ment and recycle valve positions have been reached and anycheck valve has opened (see Start-Up Sequenceon page 116).

The shut-down sequence idles the compressor by ramping thethrottle control element to an idle level, where it is held until theunit is loaded (see Shut-Down Sequenceon page 117).


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Control ElementFeatures

The actuator control signal can be clamped, adapted to a director reverse, linear, quick-opening, or equal-percentage valve, andcompensated for a deadband (see Output Variableson page 107).The controller can also detect an excessive deviation of the actuatorcontrol signal from its intended value (see Output Loopback Testonpage 49) or of the control element from its intended position (see

Valve Position Teston page 50).

When there are two control elements that affect the compressorthroughput, they can be manipulated by defining both of the control-lers analog output signals as separate functions of the performancecontrol response (see Split Range Outputon page 48).

SerialCommunication

All Series 3 Plus Controllers are equipped with four serial communi-cation circuits (see Serial Portson page 55):

Ports 1 and 2 are used to coordinate their actions with otherCCC controllers (see Loop Decoupling, Speed Tracking, Load

Sharing, Automatic Sequencing, and Redundant ControllerTracking).

Ports 3 and 4 are used for computer communication and controlusing Modbus RTU commands (see Chapter 2and the Series 3Plus Performance Controller Modbus Data Sheet[DS302/M]).This allows a host control system or a computer running control-ler support software (such as our COMMAND system) tomonitor or even control the operation of your compressor. Someof our support programs can also change the configuration andtuning of the controller.

Configuration andTuning

Each Performance Controller is adapted to its specific application byassigning values to its configuration and tuning parameters (seeAppendix A). This can be done from the Engineering Panel or acomputer running one of our configuration programs.

If your application requires routine changes to a controllers configu-ration or tuning, up to three sets of alternate parameter values canbe stored. Engineering Panel procedures are provided for definingthese alternate sets, determining which one is in use, and switchingto a different one (see Alternate Parameter Setson page 119).
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Chapter 2 OperationThis chapter describes the operation of the Performance Controller.

OperatorInterfaces

This section summarizes the controller features that can be oper-ated via its front-panel, remote I/O, and Modbus interfaces.

The front-panel keys, LEDs, and readouts can be used to selectmanual or automatic operation, switch between the local and remoteset point, raise or lower the local set point, and manually vary thecontrol response, as described in the Series 3 Plus PerformanceController Operator Interface Description[DS302/O].

The controllers remote I/O features (see Chapter 3) are primarily forintegration with other devices. Discrete inputs can be used to selectthe operating state or to trigger alternate capacity control. Discreteoutputs can be used to implement external alarms and indicators forvarious operating conditions. Process variable analog inputs can bemonitored directly, while some internal variables can be monitoredvia analog outputs.

The Modbus interface can be used to monitor the operation of thecompressor and controller, select automatic or manual operation,set either the remote or local capacity control set point and switchbetween them, change the limiting control thresholds, and manuallyset the intended control valve position, as described in the Series 3Plus Performance Controller Modbus Data Sheet[DS302/M].

Note: Because all three interfaces are always active, the compressor canbe monitored and controlled using any combination of their features.
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ContinuousOperation

The operation of a Performance Controller depends on whether it isa Stand-Alone Controllerthat regulates a pressure or flow by manip-ulating the throughput of a single compressor, a Station Controllerthat regulates the throughput of a series or parallel compressornetwork, or a Load-Sharing Controllerthat regulates the throughputof one compressor in such a network.

In any of these applications, a Performance Controller will select itsRun state when its loading sequence terminates, and will remain inthat state until the operator initiates the idling sequence or a drivershutdown (see Sequencing Operationon page 33). The operatingstate will display as Status RUN and the Modbus Startedand Star-tup Donediscretes and any Run relays will be set.

Stand-AloneController

When a single-compressor Performance Controller is operatingautomatically in its Run state, it varies its Control Element Positionto satisfy its Capacity Controland Capacity Limitingobjectives.

Control ElementPosition

The throughput of a stand-alone or load-sharing compressor can becontrolled by varying the speed set point of a speed controller orgovernor or the position of its guide vanes or throttle valve.

In any case, the position of that control element can be monitoredvia the OUT readout, Modbus Displayed OUTregister, or analogoutput OUT1. Analog output OUT2 (and the Analog Output 2regis-ter) can also be configured to transmit that signal.

The Modbus High Clampor Low Clampdiscrete bit will be set if thecontrol response equals the corresponding clamp.

If the controller has been configured to use both analog outputs tomanipulate control elements (see Split Range Outputon page 48),both analog outputs are calculated as configurable functions of theperformance control response, so that the displayed OUT signalremains an essentially linear indication of overall performance orthroughput. This feature can be used to regulate both the rotationalspeed or a throttling valve and the guide vane position.

Capacity Control The controller can regulate either a single-input variable (usually aflow or pressure signal), a compression ratio calculated from twopressure inputs, or a mass flow rate calculated from flow, pressure,

and temperature inputs for either one or two streams (see CapacityControl Variableon page 59). The PV and SP readouts normallydisplay the value and set point for this variable, which a Modbushost can monitor via the Displayed PVand Displayed SPregisters.OUT2 (and the Analog Output 2register) can also be configured totransmit either signal. The controllers individual analog inputs canbe monitored via the front-panel AUXiliary readout Measured Vari-ablesmenu or Modbus Channel #registers.
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Depending on how the set point is set up (see CV1 Set Pointonpage 72), it can be controlled either by a remote device or from theFront Panel:

Pressing the Raise key while the controller is operating auto-matically increases the local set point, while pressing the Lowerkey reduces it.

If the Computer Remote Set Pointis disabled, the local set pointcan also be changed by writing to the Capacity SPregister andthe remote set point (if enabled) is controlled via an analoginput. Depending on your application, that signal might be con-trolled by a remote device or a potentiometer on an auxiliarycontrol panel.

If the Computer Remote Set Pointis enabled, the remote setpoint can be changed only via the Capacity SPregister and thelocal set point can only be changed from the Front Panel.

If the local and remote set point are both enabled, you can switchbetween them by pressing the REMOTE/LOCAL key or setting andclearing the Remotecoil. When you do so, the actual set point doesnot change because the newly selected set point is initialized to thecurrent value of the previously selected set point. However, a newlyselected analog remote set point will then ramp to the most recentvalue sent by the remote device.

When the remote set point is selected, the Remote LED is lit andany Remoterelays and the Modbus Remotecoil and discrete areset. When the local set point is selected, the Local LED is lit and theremote indicators are cleared.

Alternate Control The controller can be configured to switch to local set point controlof an alternate process variable when discrete input D6 is asserted(see Alternate Capacity Controlon page 74). The PV and SP read-outs and registers then display the alternate variable and set point,while the Local LED flashes to alert the operator. A Modbus hostcan detect this condition by monitoring the sixth DO Statebit.

The local set point for this variable can then be varied by pressingthe front-panel Raise and Lower keys. When D6 is cleared, CV1control is restored and its selected set point is ramped from thatvariables current value to its previous local or current remote value.

Note: If necessary, a Modbus host should select the set point it controlsbefore writing to the Primary SP register.
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Capacity Limiting A stand-alone or load-sharing Performance Controller can also beset up to limit either of two capacity limiting variables if they movebeyond prescribed high or low control thresholds. In that event, theLimit LED will light, any Limitrelays and the Modbus Limitdiscretewill be set, and the capacity control (or load-balancing) variable maydeviate significantly from its set point.

Pressing the DISPLAY LOOP 2 or DISPLAY LOOP 3 key will tem-porarily display the corresponding limiting variable and its controlthreshold in the PV and SP readouts. A Modbus host can monitorthese variables via the corresponding Channel #register, and canmonitor or vary their set points via the Limiting SP2and LimitingSP3registers.

Station Controller In a Series 3 Plus Control System for load-sharing compressors, amaster Performance Station Controllerregulates a header flow rateor pressure by indirectly manipulating the individual compressor

throughput and recycle (or blow-off) rates. This is accomplished bybroadcasting changes in its control response to the Antisurge andLoad-Sharing Controller, which then manipulate their control ele-ments to efficiently and safely satisfy the station control objective.

A Station Controller operates just like a Stand-Alone Controller,except that its station control signal (SCS) is a serial transmission tocompanion controllers rather than an analog signal to a valve orguide vane actuator or speed governor. Because those companionsrespond to changes in the SCS, its actual value has no physical sig-nificance. It is usually configured as though it is manipulating asignal-to-close valve. If its value falls below its low clamp or risesabove its high clamp, it is simply reset to 50 percent.

The SCS can be monitored via the Station Controllers OUT read-out, Displayed OUT register, or OUT1. Its OUT2 (and Analog Output2register) can also be configured to transmit that signal.

If Station Controller needs to but cannot increase the throughput ofits compressor network because all of its Load-Sharing Controllers

are load-limited or fail to respond to queries, it will set any LoadedPrimary(LodP) relays and its Modbus Loaded Primarydiscrete bit.In addition, an Automatic Suspensionis triggered if no Load-SharingController is available to help control the primary capacity variable.

In a system utilizing Dual-Loop A/P Unit Controllers, various systemperformance variables calculated by the Station Controller (see Cal-culated Variable Displayson page 101) can be monitored via theCalculated Variablesmenu and the corresponding Modbus registers(Efficiency, Flow, MaxQ, Power, and UsrQ).

Note: Do not be alarmed if the OUT display of a Station Controller sud-denly jumps from 00.0 or 99.9 to a value near 50.0.
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Load-SharingController

When a Load-Sharing Controller is operating automatically in itsRun state, it varies its Control Element Positionto satisfy its PrimaryCapacity Controland Load Balancingor Capacity Limitinggoals.

Such a Performance Controller sets any Loaded Secondary(LodS)relays and its Modbus Loaded Secondarydiscrete bit when it cannot increase its compressors performance in response to a risingstation control signal. In addition, its Load-Sharing Fallbackwill betriggered if communication with the Station Controller breaks down.

Primary CapacityControl

If the network throughput needs to be reduced and the compressorsare already operating near their surge control limits, the AntisurgeControllers will provide that reduction by increasing their recycle orblow-off rates, as described in the Load Sharingsection in Chapter2 of IM301. Otherwise, the Load-Sharing Controllers will reduce net-work performance by closing their control elements or reducing theirspeed set points in response to a declining station control signal.

Load Balancing Load-Sharing Controllers use their capacity control loops to distrib-ute the total load among all operating compressors in the network(except when overridden by a limiting control loop):

For compressors operating in series, the overall load distributionis balanced by equalizing a load-balancing variable based ondistance-from-surge, recycle flow, and speed or compressionratio.

For machines operating in parallel, load-balancing equalizesonly the compressors distances from surge. If desired, a sepa-rate recycle balancing algorithm can be used to evenly

distribute the total load when the compressors are recycling.

Whenever a Load-Sharing Controller is operating automatically withits remote set point selected, it calculates this balancing variable forits own compressor and compares it to an average-value set pointreceived from the Station Controller. Those two variables are dis-played by the PV and SP readouts (and can be monitored via theModbus Displayed PVand Displayed SPregisters). The balancingresponse calculated from the resulting deviation is added to thePrimary Capacity Controlresponse.

Load-SharingFallback

If communication with the Station Controller is disrupted, that con-troller selects its Capacity Control Fallback(see page 67), or the D6input is asserted, a Load-Sharing Controller can fall back to local setpoint control of its compressors throughput (see Load-Sharing Fall-backon page 96). The front-panel Remote LED then goes out, theLocal LED starts flashing, the Fallback LED lights (unless D6 trig-gered this condition), and the Modbus Fallbackdiscrete is set. Loadsharing will then be automatically resumed when the condition thattriggered the fallback is corrected.
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Shutdown If a Performance Controller is operating in its Run state (see Contin-uous Operationon page 28), it will assume the compressor is beingshut down when a designated analog input falls below its start-upthreshold or the stop discrete input is asserted. In practice, this usu-ally means the driver is either being shut down or a stop or idleswitch has been set.

A Performance Controller that is coordinating its sequences withthose of a Series 3 Plus Speed or Fuel Controller will idle its com-pressor (and signal its companions that it has done so) when thatcontrollers shut-down sequence is initiated, unless it has alreadybeen initiated by a switch.

Any Run relays and the Modbus Startup Donediscrete are thencleared and the control response is ramped downward at a constantrate until it reaches its stop/idle level. While it is ramping down, theAUXiliary readout displays the operating state as Status RAMP.When that ramp concludes, that readout changes to Status STOP.

If the compressors Antisurge Controller has been configured toparticipate in automatic startups and shutdowns, it will either rampits valve open or open it as quickly as possible as soon as the Per-formance Controller initiates its shut-down ramp (see the Shutdownsection in Chapter 2 of IM301).

Stop/Idle State After a Shutdownhas finished ramping the control response, a Per-formance Controller will operate in its stop/idle state as long as anystop or idle request is set. In practice, this usually means the driveris either stopped or a stop or idle switch is set.

This operating state displays as Status STOP and clears the Mod-bus Starteddiscrete unless the compressor is idling. The controlresponse is held at its stop/idle level, which is often zero. If used toposition a throttling valve, that signal would then hold the valve fullyclosed to prevent back-flow through the compressor.

If the compressors Antisurge Controller has been configured to par-ticipate in automatic startups and shutdowns, it will hold its controlvalve fully open (to allow any unintended flow to bypass the com-pressor). If its purge response is triggered, however, it will fully closethat valve so purge gas can be forced through the compressor (see

the Stop Statesection in Chapter 2 of IM301).
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Startup If a Performance Controller is operating in its Stop/Idle State, astartup will be initiated as soon as all stop/idle requests are cleared.In practice, this usually means the driver is running and any stop oridle switches are cleared or in their run positions. A PerformanceController that is coordinating its sequences with those of a Series 3Plus Speed or Fuel Controller will load its compressor only after the

turbine controllers start-up sequence has been completed.

The operating state display then changes to Status RAMP andany Run relays and the Modbus Starteddiscrete are set. After ashort delay, the controller signals its companions that it has selectedits Run state, and the control response starts to rise at a constantrate. During this ramp, the local set point can be varied (if selected)from either the Front Panel or a Modbus host. When the controlresponse reaches its minimum operating level, closed-loop controlis initiated, the status display changes to Status RUN, and theStartup Donediscrete is set.

If the compressors Antisurge Controller has been configured to par-ticipate in automatic startups and shutdowns, it will initiate closed-loop control when its inputs indicate the compressor is running andits specified companion selects its Run state. It will then slowly closethat valve until it is fully shut or the minimum safe recycle or blow-offflow rate is reached (see the Startupsection in Chapter 2 of IM301).

Load-SharingStartups

The sequencing features of a parallel compressor networks StationController are usually disabled, as it will simply suspend its controlactions (see Automatic Suspensionon page 31) when all of thecompressors are idled or shut down. As the first compressor is

brought on-line, load sharing is initiated when its startup sequenceterminates. As subsequent compressors are loaded, their startupswill not terminate until their check valves open (see Check Valveonpage 115), at which point the CV Opendiscretes of their Load-Shar-ing Controllers are set.

In a system employing Dual-Loop A/P Unit Controllers, special sig-nals are provided to indicate when additional compressors shouldbe idled or loaded. The operation of such systems are described inthe Load-Sharing Sequencessection in Chapter 2 of IM303.
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Initiating Manual Manual operation can be selected at any time unless the controlleris configured for Auxiliary Limiting Control(see page 80). However:

If Speed or Output Trackingis active, the operator cannotchange the control signal (the governors remote speed setpoint) until that controller resumes remote set point speedcontrol.

In a Redundant Controlsystem, only the active controller can bemanually operated (the backup will track that selection).

Manual is selected by pressing the AUTO/MAN key while the greenAuto LED is lit or clearing the Modbus Automaticcoil. The ManualLED then lights and the Auto LED, any Auto relays, and the Auto-maticcoil and discrete bit all clear. The Remote or Local LED willremain lit to indicate the selected set point. The operating state willthen display as either Run or Stop, depending on whether the com-pressor is running.

RestoringAutomatic

Pressing the AUTO/MAN key while in manual or setting the ModbusAutomaticcoil initiates a bumpless return to automatic control. TheManual LED then clears and the Auto LED, any Auto relays, and theAutomaticcoil and discrete bit all set.

To prevent sudden throttle movements, the effective values of theCV1 set point and limiting control thresholds are initialized to thecurrent values of their control variables. The limiting thresholds arethen ramped to their parameter values, while the behavior of theCV1 set point depends on which set point is selected:

If the remote set point is selected, it is ramped from the currentvalue of CV1 to the target value from the remote source.

If the local set point is selected and Local Set Point Recallisenabled, it is ramped from the current value of CV1 to the valuethat set point had when manual was initiated.

If the local set point is selected and Local Set Point Recallis dis-abled, it remains at the current (or last good) CV1 value untilyou specifically change it.

Either way, the initial PID error will be zero. The derivative error isset to zero, and the accumulated integral response is set equal to

the last back-calculated control response. Thus, restoring automaticcontrol will not cause a sudden change in the performance controlsignal unless it is above its high clamp or below its low clamp, inwhich case it will jump back to that clamp. In addition, the ValveDead Band Compensation(see page 111)feature will rememberwhich direction the operator last moved the output while in manualand resume operation accordingly.
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Manual Override Several parameters (see Manual Overrideon page 119) determinewhether or not manual control actions are ever automatically termi-nated or restricted:

If the Capacity Manual Overrideis enabled, unrestricted manualoperation will continue even if a stop or ESD request signal isasserted or a limiting variable is beyond its control threshold.This potential hazard is indicated by flashing the front-panelManual LED when manual control is selected while this parame-ter is On.

Otherwise, asserting a stop or ESD request will restore auto-matic control (although manual could then be reselected anddoing so would terminate the resulting shutdown) and each lim-iting control loop can be independently configured to overridemanual operation when its control variable reaches its controlthreshold.

Regardless of all manual override settings, you cannot manually

adjust the control response while Speed or Output Trackingisactive.

The Limit LED will light whenever either capacity limiting variable isat or beyond its defined limit, but automatic control is temporarilyrestored (and the Limit relay and discrete bit are set) only if that vari-ables manual override has been enabled. The performance controlresponse can still be manually adjusted while a limiting override isactive, but only in the direction that would restore the out-of-rangevariable to an acceptable value.

Caution: We advise you not to permanently enable the Capacity ManualOverrideparameter.


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Fault Indicators In addition to a General Fault, which would be indicated via the FaultLED and relays, the Performance Controller can use front-panelLEDs, assignable relays, and Modbus discrete bits to indicate SerialCommunication Errors, Analog Input or Transmitter Failures, OutputFailures, and Valve Position Failures. It will also indicate when itsBackup Inputis selected or a Fallback Conditionis active due to

analog input or serial communication problems.

General Fault Each Series 3 Plus Controller has a watchdog circuit that must beregularly reset by its control program. If it does time out, it will de-energize the fault relay and reset the CPU chip, thus causing thecontrol program to restart:

If that restart succeeds, it will reset the timer, clear the relay,and temporarily set the Modbus Resetdiscrete. The Engineer-ing Panel will beep and display Reset.

If it fails, the fault relay will remain de-energized and the FrontPanel will light its Fault LED (and turn the other thirteen off).

This can indicate either a software error or a hardware problemthat prevents the control program from running.

If the fault relay has also been assigned a second function (seeFault Relayson page 52), that condition will not light the Fault LED.If that assigned function is one that has its own LED, you can tellwhy the fault relay has tripped by looking at the Front Panel.

Serial CommunicationErrors

When the controller fails to detect expected serial transmissions, itwill light the ComErr LED and set any Serial Communication Error(SerC) relays and the Modbus Port 1 Failor Port 2 Faildiscrete (seeSerial Communication Errorson page 56).

Because the exact meaning of these conditions depends on whichfeatures have been enabled, their interpretation will be highly sitespecific. Loss of Port 2 communications will disrupt load-sharing andpressure override control. A Port 1 serial error can also disrupt thosefeatures, as well as loop decoupling, automatic sequencing andoperating state selection, and redundant control.

Analog Input orTransmitter Failures

Whenever one or more analog inputs is beyond its valid range, thecontroller lights its TranFail LED and sets any Transmitter Failure(Tran) relays and the Modbus Tran Faildiscrete (see TransmitterTestingon page 45).

This condition usually indicates a failure in the input loop (transmit-ter, signal wire, and Analog PCB circuit), but might also be used toalarm undesirable process conditions.

Caution:The controllers output signal is totally unpredictable when a watch-dog fault is indicated. Process disruptions or compressor damagecan result if it is not immediately disconnected from your process.
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Tracking States The Performance Controller includes two features that allow anexternal device to manipulate its actuator control signal (ACS):

When Speed or Output Trackingis active, the ACS tracks ananalog or serial signal from a remote device.

When Redundant Controlis active, it tracks the ACS of another

Series 3 Plus Performance Controller.If either feature is active, the Tracking LED will either light (redun-dant tracking) or flash (speed tracking). Redundant tracking will alsodisplay as Status TRACK and set the Modbus Trackingdiscrete.There are no relay functions that indicate either of these states.

Speed or OutputTracking

The Performance Controller can be configured to coordinate itsactions with a turbine (or other drivers) speed governor by enablingeither of two speed tracking features:

Serial Speed Tracking(see page 85)configures a Performance

Controller to coordinate its actions with those of a Series 3 PlusSpeed or Fuel Controller.

Specifically, it will keep its ACS (which is the speed set point)equal to the turbine speed whenever the turbine controller stopsmaintaining its remote set point because it is being manuallyoperated, is using a local set point, or has encountered a limit-ing condition (for example, a temperature limit) that prevents itfrom raising or lowering the rotational speed or drive power.

If the capacity control loop pushes the turbine controller into alimit condition, the controllers will normally resolve that potential

impasse when conditions permit a reduction of the speed ordrive power. If they dont, you can prompt them to do so byselecting manual operation and pressing the Lower () key.

Analog Speed Tracking(see page 86)configures a Perfor-mance Controller to keep its ACS equal to a specified analoginput when the D4 discrete input is asserted.

This can be used to coordinate control with a speed governorfrom some other supplier. A Performance Controller can then beconfigured to request a lower speed when manual operation isselected and the Lower () key is pressed. In such applications,this may be the only way to break a speed-tracking deadlock,

which can occur if the Performance Controller raises the speedset point high enough to create a speed limiting condition andthen starts tracking that set point.

This feature can also be used to configure the PerformanceController as a signal selector for its own output signal and thatof another device. In this application, which is referred to as out-put tracking, the desired control loop is usually selected by acontrol panel switch or DCS discrete output connected to D4.
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If both features are enabled, analog tracking has priority and will beinitiated whenever D4 is asserted, even if serial tracking is active.

In any case, the controller will enter its speed tracking state evenif Manual Operationis in effect. You can still switch between theremote and local set points and change the local set point, but suchactions will not take effect until automatic, remote set point opera-tion of the speed controller is restored or D4 is cleared.

RedundantControl

If one Performance Controller has been installed as an on-line hotbackup to another (see Redundant Trackingon page 120), it will useserial communications to track the operating state, set point mode,set points (remote and local), and intended flow rate of the activecontroller whenever its own D1 discrete input is cleared.

A tracking Performance Controller lights its Tracking LED anddisplays its operating state as Status TRACK. Most of its otherLEDs will duplicate those of the main controller.

In a typical redundant system, each pair of Performance Controllersis interconnected via a Redundant Control Selector (RCS) that mon-itors their fault relays, controls their D1 inputs, and connects thevalve actuator to the selected controllers analog output. If the maincontrollers fault relay de-energizes, the RCS automatically transferscontrol of the recycle valve to the backup controller (provided that ithas not faulted as well). That controller then initiates control begin-ning from the last conditions received from the main controller.

The RCS also indicates which controller is active by lighting itsgreen MAIN or red BACK-UP LED, and you can manually select the

active controller by pressing the Switch to Back-Up or Switch toMain push-button.

Note:The RCS will not automatically return control of your process to themain controller after a fault is cleared (this must be done manually)and will never automatically or manually transfer control to a control-ler that appears to have failed.


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IM302

Chapter 3 Input/Output FeaturesThis chapter tells how to configure the analog and discrete inputsand outputs and serial communication ports.

Figure 3-1 ECC field terminals are provided by separately mounted FIOM

HardwareOptions

The Performance Controller usually uses either the Basic Compres-sor Controller (BCC) or Extended Compressor Controller (ECC)hardware configuration, as described in Chapter 1 of IM300/H.Either provides the following input and output circuits:

eight Analog Inputs(CH1 to CH8),

two standard Analog Outputs(OUT1 and OUT2),

seven Discrete Inputs(D1 to D7),

five Discrete Outputs(CR1 to CR5), and

four Serial Ports(Port 1 to Port 4).When the ECC configuration is used, all I/O terminals are providedon a separately mounted Field Input/Output Module (FIOM, seeFigure 3-1), which is connected to an Extended I/O Back Panel bya High-Density Interconnect Cable (HDIC).

Disabling InputSignals

As an aid to developing and demonstrating Series 3 Plus Perfor-mance Controllers, they include a CPU Inputs Lockout[MODE:DLOCK 6]parameter that, when enabled, configures the controller toignore its analog and discrete inputs (which can then be updated via

the Port 3 or Port 4 Modbus serial link).

Caution: An installed controller should not be operated with LOCK 6 enabled,as that would prevent it from receiving needed input signals.
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Figure 3-2 Analog input signal processing

Analog Inputs Each Series 3 Plus Controller is equipped with eight analog inputs.As described in the Analog Input Installationsection in Chapter 6 ofIM300/H, they are set up as either 0 to 5 Vdc or 4 to 20 mA inputs byinstalling resistors on either the Field Input/Output Module or setting

jumpers on the Analog PCB Assembly (if not using FIOMs).

In this manual, we will refer to both the input circuits and the associ-ated analog signals as Channels 1 through 8 (CH1 to CH8) themeaning in each case should be clear from its context.

The initial processing of these inputs and the terms used to distin-guish their various intermediate values are illustrated by Figure 3-2:

Step 1: The raw analog inputs are converted to equivalent digitalvalues called Analog-to-Digital Variables(AD1 to AD8).

Step 2: Transmitter Testingcompares each AD variable against itsindividual alarm limits.

Step 3: The AD variables are converted into percent-of-range SignalVariables(SV1 to SV8).

Step 4: Gains and biases are then applied to obtain the ProcessVariables(PV1 to PV8) used by the control calculations.

Step 5: The signal variables are also independently scaled to obtainthe Measured Variables(MV1 to MV8) displayed by the AUXil-iary readouts Analog In Menu.

AD (%)

PV = Bias +

SV (%)

(SV Gain)

PV (%)MV

MV = Min +(Span SV)

TEST 4

PV = Bias +

SV (%)

AN IN ON(e.g., 4 to 20 mA)

AN IN OFF(e.g., 0 to 10 V)

CH (V)

SV = AD

AD (%)

Failed if:

< AN IN LOW> AN IN HIGH

SV = 1.25 (AD - 20%)

Sampling

Hardware

CH (mA)

Failed if:

< AN IN LOW> AN IN HIGH

(SV Gain)

PV (%)MV

Sampling

Hardware

MV = Min +(Span SV)

TEST 4

SV (%)SV (%)
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Process Variables The analog inputs for some control calculations must be convertedto absolute values. For example, the pressure and temperatureinputs used to compute mass flow rates must be scaled as percent-ages of the highest absolute pressure their sensors can measure.These process variables are calculated by applying appropriategains and biases to the corresponding signal variables:

where:

Bias = (Offset 100) / Maximum

Gain = Range / Maximum

Maximum = absolute measurement corresponding to the highestpossible transmitter signal. If there is more than onetransmitter of a given type, this should be the largestsuch value for the group

Offset = absolute measurement corresponding to lowest possi-ble transmitter signal

PV = Process Variable, expressed as a percentage of abso-lute maximum

Range = span of the transmitter in question

The gain and bias for each process variable must be assigned to thecorresponding Process Variable Gain[COND:D GAIN #]and Pro-cess Variable Bias[COND:D BIAS #]. For unused channels, set thegain to 1.000 (.A00) and the bias to 00.0.

MeasuredVariables

The AUXiliary Displays Analog In menu is used to display the con-trollers eight signal variables, scaled to appropriate ranges, alongwith descriptive labels of your choosing. For example, you might dis-play an inlet temperature signal as:

The available choices are set up by each inputs five Measured Vari-able [COND:D DISPLAY 0] parameters. For example, the DISPLAY0 1 parameters govern the display of signal variable SV1:

Each Measured Variable Display[COND:D DISPLAY 0 #]parameter defines whether the corresponding variable can beviewed (SV1 can be displayed only if DISPLAY 0 1 is On).

Each Measured Variable Label[COND:D DISPLAY 0 # ]parameter defines the label that will precede the numeric valueof the input. Each can be any combination of eight symbols fromTable 3-1. The default labels [see page 3 of DS302/O], can berestored by entering the COND:D DISPLAY 0 0 key sequence.

PV Gain SV Bias+=

TempIn: 400
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Each signal variables Measured Variable Minimum

[COND:DDISPLAY 0 # LOW]defines the digits shown when it is zero, itsMeasured Variable Maximum

[COND:D DISPLAY 0 # HIGH]defines the digits shown when it is 100 percent, and its Mea-sured Variable Decimal

[COND:D DISPLAY 0 # ]defines thedecimal point position. Mathematically, this can be stated as:

wheren

SV is the signal variables normalized value.

Because the decimal point is a character that requires one of thefour display positions, only three digits can be displayed unless thatparameter is disabled (Off). In other words, that parameter identifiesthe digit the decimal should replace (that and all less-significant dig-its are shifted one position to the right). A value of one correspondsto the right-most, least-significant digit, while four is the left-most,most-significant digit. Thus, if DISPLAY 0 1 HIGH is 3210, the five

possible values of DISPLAY 0 1 would yield the following displayswhen SV1 is 100 percent:

0: 3210 1: 321. 2: 32.1 3: 3.21 4: .321

To obtain the most precise possible readouts, you should alwaysmake the DISPLAY HIGH parameters as large as possible. Forexample, if you want to display three digit numbers from 0 to 600,set DISPLAY HIGH to 6000 and DISPLAY to 1 (for a trailing deci-mal). This will give more precise readouts than you would get bysetting DISPLAY HIGH to 0600 and DISPLAY to 0.

If Auxiliary Display Reset

[MODE:D LOCK 9]is disabled, Measured

Variables will be displayed until another variable is selected. Other-wise, the operating state display is restored 60 seconds after theMENU or SCROLL key was last pressed.

Table 3-1 Available symbols for measured variable labels

MV Min SVn( ) Max Min( )+[ ] 10dec=

space

! " # $

% & ' ( ) * + , - . /

0 1 2 3 4 5 6 7 8 9 : ; < = > ? @A B C D E F G H I J K L M N O P

Q R S T U V W X Y Z [ \ ] ^ _ `

a b c d e f g h i j k l m n o p

q r s t u v w x y z


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Analog Outputs

The Performance Controller has two standard analog outputs, bothof which are generated as both 4 to 20 mA and 0 to 5 Vdc signals(although only one of these signals can be used for each output):

OUT1 is usually used to manipulate the compressors throttlingelement (speed set point, flow valve, or guide vanes). It can beused to drive an indicator for the intended throughput (see Actu-ator Control Signalon page 111) even if its electrical signal isnot used to manipulate a control element (for example, if thethrottling element is a Speed Controller that obtains its set pointfrom the Performance Controller via serial communication).

OUT 2 is generated as the equivalent of one of the variableslisted in Table 3-2, as specified by the Second Output AssignedVariable

[COND:D OUT 2]. Assigning that parameter the Spltvalue enables the Split Range Output, which uses both outputsto drive control elements. Otherwise, OUT2 can be used to drivean indicator for the selected variable.

The Output Loopback Testcan be used to compare the actual out-put signal to its intended value, while the Valve Position Testcan beused to compare the measured and intended positions of the finalcontrol element.

Table 3-2 Functions for OUT2

Split RangeOutput

The split range output calculates both analog outputs as functions ofthe control signal. It is often used to regulate both rotational speedor a throttling valve and the position of any guide vanes. Alternately,it can be used to define custom characterizers for both the final con-trol element and an external intended flow indicator.

This feature is enabled by selecting Splt as the Second Output

Assigned Variable[COND:D OUT 2]. The OUT1 Characterizer[COND:D f(X) 1 # and X 1 #]and OUT2 Characterizer[COND:D f(X)2 # and X 2 #]then define those signals as independent functions ofthe control signal, as shown in Figure 3-3. In addition, the resetrates for the Capacity Controland Load-Sharing Fallbackor Alter-nate Capacity Controlloops and the Primary Capacity Controlgainare all multiplied by the OUT2 Gain Multiplier[COND:D Q 1]whenthe actuator control signal is above the Split Point[COND:D LVL 1].

Code Signal

Out Actuator Control Signal(see page 111)

PV Capacity Control Variable(see page 59)

SP CV1 Set Point(see page 72)

Splt enables Split Range Output(see page 48)


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Figure 3-3 Characterization of the split range output signals

When using this feature, disable both the Valve Flow Characterizer[MODE:P fC 8]and Display Output Reverse[MODE:P fD 1]andconfigure the control loops for a direct-acting control element. Ifeither control element is reverse-acting, its output characterizer canthen be defined as a decreasing function. Independent outputclamps can also be built into each characterizer (the coordinates ofany point serving as a clamp are its valve flow and position limits).

If one of the control elements is a Series 3 Plus Speed Controller, itshould be set up to use the corresponding Performance Controlleranalog output as an analog remote set point (see the Speed SetPointsection in Chapter 5 of IM307). However, serial communica-tions can still be used to coordinate other aspects of their operation(see Speed Trackingon page 83and Coordinated Sequencingonpage 117).

Output LoopbackTest

The controller can be configured to energize one or more discreteoutputs to indicate an excessive deviation between the measuredand intended values of the actuator control signal.

This feature is set up by connecting OUT1 to analog input CH8, asdescribed in the Analog Output Installationsection in Chapter 6 ofIM300/H. Any discrete output assigned the output failure (OutF)

Control Signal (%)

OUT2(%)

100

COND:D X 2 n = CSn

COND:D f(X) 2 n = OUT1n

0

n = 0

n = 9

OUT1(%)

100

100

COND:D X 1 n = CSn

COND:D f(X) 1 n = OUT1n

0

n = 0

n = 9

0

Note:

When this feature is selected, the OUT readout will display the value

of the actuator control signal.
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Discrete Inputs All Series 3 Plus Performance Controllers are equipped with sevendiscrete inputs (D1 to D7) that can be used to trigger the control fea-tures listed in Table 3-3. The threshold level above or below whichthese inputs are asserted or cleared is listed on the Series 3 PlusCompressor Controllers Hardware Specifications[DS300/H]:

Check Valve The controller will assume there is a closed discharge check valve ifD5 is set (see Check Valveon page 115).

Fallback Setting D6 will trigger the load-sharing capacity control fallback (seeLoad-Sharing Fallbackon page 96) or alternate capacity control, ifeither of those features is enabled (see Alternate Capacity Controlon page 74).

Purge D3 can serve as the purge request for an Antisurge Controller, asdescribed in the Operating State Request Signalssection in Chapter9 of IM301.

Recall Setting D7 will recall the second alternate parameter set and clear-

ing it will recall the first, provided that feature is enabled (seeAlternate Parameter Setson page 119).

Speed Tracking Setting D4 will cause the control signal to track the compressorspeed via a specified analog input, provided that feature is enabled(see Analog Speed Tracking(see page 86)).

Stop Setting D2 will initiate the idle sequence, provided that feature isenabled and configured to use D2 rather than an analog input (seeOperating State Request Signalson page 114).

Tracking Setting D1 will cause this controller to track the operation of a com-panion Performance Controller, provided that feature is enabled

(see Redundant Trackingon page 120).

Table 3-3 Discrete input functions

Input Function

D1 Redundant Trackingrequest

D2 Stoprequest

D3 Purgerequest

D4 Speed Trackingrequest

D5 Check Valveclosed

D6 Fallbackrequest

D7 Recallalternate parameter set
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The offending port can be determined and additional diagnosticinformation obtained via the following Engineering Panel tests:

The Serial Port 1 Test

[MODE COMM 3]indicates (by control-ler ID number) the controllers from which Port 1 transmissionsare or are not being received (regardless of whether or not suchtransmissions are needed or expected). The status of control-lers that are transmitting will display as Good, while the statusof controllers from which no transmissions are being receivedwill display as Bad. A serial error is indicated only if the statuso

Documents

Performance Controler IM302