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					Abu Dhabi National Oil Co. ADNOC Technical Institute

INSTRUMENTATION
PROCESS CONTROL FUNDAMENTALS

UNIT 5 FOXBORO IA DCS

FOXBORO IA DCS DATE OF ISSUE 8-DEC-09

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ADNOC TECHNICAL INSTITUTE

UNITS IN THIS COURSE

UNIT 1

BASIC CONTROL THEORY

UNIT 2

TUNING A CONTROLLER

UNIT 3

INTRODUCTION TO DCS AND PLC

UNIT 4

HONEYWELL TDC 3000 DCS

UNIT 5

FOXBORO IA DCS

UNIT 6

PRACTICAL TASKS

FOXBORO IA DCS DATE OF ISSUE 8-DEC-09

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TABLE OF CONTENTS
Paragraph 5.0 UNIT OBJECTIVES 5.1 INTRODUCTION 5.2 THE BASIC FOXBORO IA SYSTEM 5.2.1 Introduction 5.2.2 Foxboro IA System Layout 5.2.3 Foxboro IA Hardware 5.3 TYPICAL FOXBORO IA CENTRAL CONTROL ROOM Page 4 5 5 5 5 7 11

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ADNOC TECHNICAL INSTITUTE 5.0 UNIT OBJECTIVES The student will be able to    Explain the terms used by Foxboro in their DCS. Sketch the layout of the Foxboro enclosure. Draw a simplified diagram of the Foxboro DCS and explain what the main components do.

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ADNOC TECHNICAL INSTITUTE 5.1 INTRODUCTION The aim of the unit is to introduce the Foxboro Intelligent Automation (Fox IA) DCS. It explains the terms used by Foxboro and shows how IA fits the 5 level concept of a distributed control system.

5.2 THE BASIC FOXBORO IA SYSTEM 5.2.1 Introduction The Foxboro IA system is one of the most up to date distributed control systems for oil/gas production. It is used for process control by ADCO and Ruwais (FERTIL). The Foxboro system is an improvement on older DCS's as it uses an "Open Industrial System". This means the software used to programme the DCS is industrial standard (UNIX). It can be used to set up both the Foxboro system and equipment from other manufacturers connected to it. It has improved data handling so there is no need for "handshaking". It is also has a system called "Reporting by Exception". measurements are only changed if their values change. This means that

5.2.2 Foxboro IA System Layout Figure 5-1 shows the layout of a typical Foxboro IA DCS. The levels of control are the same as the Honeywell but the system is simpler at the 1, 2 and 3 level. So, it only needs one data transmission highway. The following points should be noted. 1) The diagram shows a large Integrated Control System (e.g. control and management of a multi-platform offshore oil field). level consists of a central control room. accommodation platform. The supervision level is located on each platform. The area management This is usually on the It can display information from all the

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ADNOC TECHNICAL INSTITUTE platforms. The group management display is at the headquarters on shore. Data transmission between units can be either by cable using a high level LAN (ETHERNET) or by radio link (e.g. satellite, microwave link, etc.) 2) The I/O conditioning units and the control processors are located in one unit. This can be placed anywhere in the plant. 3) Signals to and from the control room are placed on what Foxboro call a "Redundant Nodebus". The same cable is used for the control room and field units. If the field units are a long way from the control room a "Nodebus Extender" (NBE) is used. This maintains the voltage level of the transmitted data. 4) The following processors are connected to the nodebus: AP WP Applications Processor. This allows data to be processed for the Historian, Printer, etc. Workstation Processor. This allows data to be processed for the workstation, (e.g. VDU, keyboard, mouse/trackball, touch screen, etc.). COMM Communications Processor. PC which uses ASCII) FDG Foreign Device Gateway Processor. This allows data to be processed so that signals can be received or sent through a modem. platform, etc. CBLI Carrier Based LAN Interface. This unit converts the UNIX programming system (protocol) of the nodebus to a protocol for the high level LAN (e.g. Ethernet) and viceversa. The area management system uses the same equipment as in the control room. Therefore, there must be a CBLI at both ends of the high level LAN. The data can be sent to another location, This allows data to be processed for items not using UNIX, (mainly the engineer's

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ADNOC TECHNICAL INSTITUTE

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ADNOC TECHNICAL INSTITUTE 5.2.3 FOXBORO IA HARDWARE Foxboro combines the first level (field devices) and second level (control devices) into one unit. This unit is called an "Enclosure". It can be placed at any suitable position in the plant. enclosure in a plant. Figure 5-2 shows a Foxboro

WEATHER - PROOF ENCLOSURE FOR USE IN ZONE 1 AREAS. PROVIDES LOCAL LOOP CONTROL, AND THUS GREATLY REDUCES INSTRUMENT WIRING.

Figure 5-2 Foxboro IA Enclosure

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N B E

TO CONTROL ROOM REDUNDANT NODEBUS

STATIONS

REDUNDANT NODEBUS

C P

C P

FIELDBUS (REDUNDANT)

FIELDBUS MODULES
F F B B M M

INPUT FROM FIELD OUTPUT TO CONTROL VALVE
I/P

Figure 5-3 Foxboro Industrial Enclosure
Figure 5-3 shows the inside of an enclosure. The bottom two racks have slots into which the I/O units are fitted. input/output. These are called Field Bus Modules (FBM) by Foxboro. These FBM's can process any type of field

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ADNOC TECHNICAL INSTITUTE Some FBM examples are given below. FBM FBM 01 FBM 02 FBM 03 FBM 04 FBM 10 FBM 18 FUNCTION 0-20 mA INPUT THERMOCOUPLE /mV INPUT RTD INPUT 0-20mA INPUT / OUTPUT 120 VAC INPUT / OUTPUT SWITCHED SMART TRANSMITTERS POINTS 8 AI 8 AI 8 AI 4AI/4AO 8DI/8DO 8 AI

AI DI AO DO POINTS

ANALOG INPUT DIGITAL INPUT ANALOG OUTPUT DIGITAL OUTPUT Number of inputs/outputs available on each FBM

The top of the enclosure has slots which hold the system processors (called stations by Foxboro). A plant enclosure normally has only CP's and NBE's. The CP's control the area loops and the NBE extends the redundant nodebus to the supervisor's control room.

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ADNOC TECHNICAL INSTITUTE 5.3 TYPICAL FOXBORO IA CENTRAL CONTROL ROOM

KEYBOARDS

HISTORIAN

VDU

PRINTERS ENGINEERS PC

AP

WP

COMM NBI

REDUNDANT NODEBUS

CBLI
FROM LOCAL CONTROL

INDUSTRIAL ENCLOSURES

ENCLOSURE NODEBUSES CONNECTED TOGETHER

MARSHALLING CABINETS FIELD INPUTS AND OUTPUTS ON MAIN PLATFORM

FIELD CONNECTIONS PLUS IS BARRIERS

Figure 5-4 Foxboro IA CCR Figure 5-4 shows the typical layout of a Foxboro Central Control Room (CCR).

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ADNOC TECHNICAL INSTITUTE A basic description of the system is as follows: 1) The Central Control Room processes signals from both a remote location, using a CBLI, and from equipment on the main platform where the CCR is located. 2) Main platform signals are routed through what are called marshalling cabinets. These contain the IS barriers. A Foxboro IA FBM is not intrinsically safe. 3) The industrial enclosures are the same as the ones described in 5.3.2. CCR. 4) Whether the system is for local supervisory control or CCR control the equipment is the same. It is all run from a Redundant Nodebus connected by either NBEs or CBLIs. 5) The AP, WP, and COMM processors can be fitted into a station in the enclosure or in slots under the workstations. 6) The Nodebus Interface (NBI) connects the Nodebus to the engineers PC. This is done so that the engineer does not interfere with operators using the workstations. 7) The Nodebus has terminators to stop data reflections, (in the same way as the Honeywell TDC 3000). 8) All Nodebus connectors can be removed without affecting the other units connected to the bus. 9) Remember that loop control is done by the CP. A fault on the CCR Nodebus will not cause the plant to lose control. 10) The operator on the workstation normally only supervises the plant operations. However, he can switch a control loop from automatic to manual and perform set point changes. However, they need no weather-proofing and Zone 1 protection. These are usually located in a terminal room behind the

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ADNOC TECHNICAL INSTITUTE 11) PID control functions and PLC sequence changes can only be done by the systems technician or engineer. This is usually done via the engineer's PC using a "password" know only to the engineering staff. 12) Figure 5-5 shows the typical layout of a Foxboro control room.

Figure 5-5 Foxboro IA Workstations

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DOCUMENT INFO
Description: Instrumentation Course