Haward Technology Middle East 1Section 16
Process Control, Instrumentation and Safeguarding
Section 16
SCADA Systems
Haward Technology Middle East 2Section 16
Process Control, Instrumentation and Safeguarding
SCADA Systems
TOPICS
Basic Definitions
Levels of Hierarchy
SCADA Configuration
Haward Technology Middle East 3Section 16
Process Control, Instrumentation and Safeguarding
BASIC DEFINITIONSSCADA Systems
Haward Technology Middle East 4Section 16
Process Control, Instrumentation and Safeguarding
SCADA is the acronym for Supervisory Control And Data Acquisition.
In Europe, SCADA refers to a large-scale, distributed measurement and control system, while in the rest of the world SCADA may describe systems of any size or geographical distribution.
SCADA systems are typically used to perform data collection and control at the supervisory level. Some systems are called SCADA despite only performing data acquisition and not control.
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 5Section 16
Process Control, Instrumentation and Safeguarding
The supervisory control system is a system that is placed on top of a real-time control system to control a process that is external to the SCADA system (i.e. a computer, by itself, is not a SCADA system even though it controls its own power consumption and cooling).
This implies that the system is not critical to control the process in real time, as there is a separate or integrated real-time automated control system that can respond quickly enough to compensate for process changes within the time constants of the process.
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 6Section 16
Process Control, Instrumentation and Safeguarding
The term SCADA usually refers to centralized systems which monitor and control entire sites, or complexes of systems spread out over large areas (on the scale of kilometers or miles).
Most site control is performed automatically by remote terminal units ("RTUs") or by programmable logic controllers ("PLCs").
Host control functions are usually restricted to basic site overriding or supervisory level intervention.
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 7Section 16
Process Control, Instrumentation and Safeguarding
As an example, a PLC may control the flow of cooling water through part of an industrial process, but the SCADA system may allow operators to change the set points for the flow, and enable alarm conditions, such as loss of flow and high temperature, to be displayed and recorded.
The feedback control loop passes through the RTU or PLC, while the SCADA system monitors the overall performance of the loop
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 8Section 16
Process Control, Instrumentation and Safeguarding
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 9Section 16
Process Control, Instrumentation and Safeguarding
There is a fair degree of confusion between the definition of SCADA and process control systems.
SCADA has the perception of remote or distance operation.
The inevitable question is how far is far? Typically this means over a distance such that
the distance between the controlling location and the controlled location is so great that direct wire control is impractical (n.b. the communications link is a critical component of the system).
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 10Section 16
Process Control, Instrumentation and Safeguarding
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 11Section 16
Process Control, Instrumentation and Safeguarding
Data acquisition begins at the RTU or PLC level and includes meter readings and equipment status reports that are communicated to SCADA as required.
Data is then compiled and formatted in such a way that a control room operator using the HMI can make supervisory decisions to adjust or override normal RTU (PLC) controls.
Data may also be fed to a Historian, often built on a commodity Database Management System, to allow trending and other analytical auditing
BASIC DEFINITIONS
SCADA Systems
Haward Technology Middle East 12Section 16
Process Control, Instrumentation and Safeguarding
TYPICAL DATABASE MANAGEMENT SYSTEM
BASIC DEFINITIONS
SCADA Systems
SCADA(stand Alone)
SCADA(Redundant)
CorporateDatabase
Applications
CorporateE-mailSystem
CorporateWeb
Application
CitectSCADAReports
Web Client(Analysis & Reporting)
Excel Client(Analysis)
Custom Clients
Historian
Haward Technology Middle East 13Section 16
Process Control, Instrumentation and Safeguarding
Levels of
Hierarchy
SCADA Systems
Haward Technology Middle East 14Section 16
Process Control, Instrumentation and SafeguardingSCADA Systems
Haward Technology Middle East 15Section 16
Process Control, Instrumentation and Safeguarding
LEVELS OF HIERARCHY
On a complex SCADA system, there are essentially 5 levels of hierarchy.
Field level instrumentation and control devices Marshalling terminals and RTU’s Communications systems The master station(s) The commercial data processing department computer system
SCADA Systems
Haward Technology Middle East 16Section 16
Process Control, Instrumentation and Safeguarding
1 Field Level and Instrumentation Devices
SCADA Systems
Haward Technology Middle East 17Section 16
Process Control, Instrumentation and Safeguarding
1 FIELD LEVEL AND INSTRUMENTATION DEVICES
SCADA Systems
Haward Technology Middle East 18Section 16
Process Control, Instrumentation and Safeguarding
1 FIELD LEVEL AND INSTRUMENTATION DEVICES
SCADA Systems
Haward Technology Middle East 19Section 16
Process Control, Instrumentation and Safeguarding
The field mounted devices are no different from any other application.
In many cases, the process may be petrochemical, in which case, consideration must be given to intrinsic safety problems.
It would be logical to assume the “smart” devices would be adopted.
This also assumes that a network system would be used at this level
1 FIELD LEVEL AND INSTRUMENTATION DEVICES
SCADA Systems
Haward Technology Middle East 20Section 16
Process Control, Instrumentation and Safeguarding
SCADA System for Pipelines Showing Field Instruments
1 FIELD LEVEL AND INSTRUMENTATION DEVICES
SCADA Systems
Main Control Room
SCADA
RTU
ComnSpike
RTU
OutletDock Valve
Dock Valve
ComnSpike
ComnSpike
ComnSpike
Dock Valve
RTU
P
T
O P
T
P
P
T
O
Haward Technology Middle East 21Section 16
Process Control, Instrumentation and Safeguarding
2 Remote Terminal Units
SCADA Systems
Haward Technology Middle East 22Section 16
Process Control, Instrumentation and Safeguarding
2 REMOTE TERMINAL UNIT
SCADA Systems
Commercial Data Processing System
Master station
Communication system
Communication system
RTU’s
Field Level
Field devices (analog & digital Input/output)
Mainframe computerData processing system
Mainframe computerData processing system
Master station
Master station
Sub-Master station
Sub-Master station
Sub-Master station
Sub-Master station
Haward Technology Middle East 23Section 16
Process Control, Instrumentation and Safeguarding
TYPICAL REMOTE TERMINAL UNIT
2 REMOTE TERMINAL UNIT
SCADA Systems
Haward Technology Middle East 24Section 16
Process Control, Instrumentation and Safeguarding
The RTU provides an interface to the field analogue and digital signals situated at each site.
Sometimes referred to as a Remote Telemetry Unit, as its name implies, this device is a standalone data acquisition and control unit.
Generally microprocessor based.
The main function of an RTU, is to monitor and control equipment at some remote location from the central station.
2 REMOTE TERMINAL UNIT
SCADA Systems
Haward Technology Middle East 25Section 16
Process Control, Instrumentation and Safeguarding
Typical RTU modules include the following modules
Control processor and associated memory. Analogue I/O Digital I/O Counter inputs Communication interfaces Power supply RTU rack and enclosure
2 REMOTE TERMINAL UNIT
SCADA Systems
Haward Technology Middle East 26Section 16
Process Control, Instrumentation and Safeguarding
2 REMOTE TERMINAL UNIT
SCADA Systems
Haward Technology Middle East 27Section 16
Process Control, Instrumentation and Safeguarding
3 Communication Systems
SCADA Systems
Haward Technology Middle East 28Section 16
Process Control, Instrumentation and SafeguardingSCADA Systems
Haward Technology Middle East 29Section 16
Process Control, Instrumentation and Safeguarding
3 COMMUNICATIONS SYSTEM
The communications systems provides the pathway for communications between the master and remote sites.
This communications system can be radio, telephone, microwave or satellite.
Specific protocols and error detection philosophies are used for efficient and optimum transfer of data.
SCADA Systems
Haward Technology Middle East 30Section 16
Process Control, Instrumentation and Safeguarding
4 Master Stations
SCADA Systems
Haward Technology Middle East 31Section 16
Process Control, Instrumentation and Safeguarding
4 MASTER STATIONS
SCADA SystemsCommercial Data Processing System
Master station
Communication system
Communication system
RTU’s
Field Level
Field devices (analog & digital Input/output)
Mainframe computerData processing system
Mainframe computerData processing system
Master station
Master station
Sub-Master station
Sub-Master station
Sub-Master station
Sub-Master station
Haward Technology Middle East 32Section 16
Process Control, Instrumentation and Safeguarding
The master station (and sub-masters) gather information from the various RTU’s and generally provide an operator interface for display of information and control of remote sites.
In large telemetry sites, sub-master sites gather information from remote sites and act as a relay back to the control master station.
4 MASTER STATIONS
SCADA Systems
Haward Technology Middle East 33Section 16
Process Control, Instrumentation and Safeguarding
A SCADA system includes a user interface, usually called Human Machine Interface (HMI).
The HMI of a SCADA system is where data is processed and presented to be viewed and monitored by a human operator.
This interface usually includes controls where the individual can interface with the SCADA system.
HMI's are an easy way to standardize the facilitation of monitoring multiple RTU's or PLC's (programmable logic controllers).
4 MASTER STATIONS
SCADA Systems
Haward Technology Middle East 34Section 16
Process Control, Instrumentation and Safeguarding
Usually RTU's or PLC's will run a pre programmed process, but monitoring each of them individually can be difficult, usually because they are spread out over the system.
Because RTU's and PLC's historically had no standardized method to display or present data to an operator, the SCADA system communicates with PLC's throughout the system network and processes information that is easily disseminated by the HMI.
4 MASTER STATIONS
SCADA Systems
Haward Technology Middle East 35Section 16
Process Control, Instrumentation and Safeguarding
HMI's can also be linked to a database, which can use data gathered from PLC's or RTU's to provide graphs on trends, logistic info, schematics for a specific sensor or machine or even make troubleshooting guides accessible.
In the last decade, practically all SCADA systems include an integrated HMI and PLC device making it extremely easy to run and monitor a SCADA system.
4 MASTER STATIONS
SCADA Systems
Haward Technology Middle East 36Section 16
Process Control, Instrumentation and Safeguarding
A TYPICAL SCADA APPLICATION
REMOTE TERMINAL UNITS
SCADA Systems
Oil TreatmentPlant
Oil Production
Wells
Oil Gathering
Field
Haward Technology Middle East 37Section 16
Process Control, Instrumentation and Safeguarding
5 Management Level
SCADA Systems
Haward Technology Middle East 38Section 16
Process Control, Instrumentation and Safeguarding
5 MANAGEMENT LEVEL
SCADA Systems
Haward Technology Middle East 39Section 16
Process Control, Instrumentation and Safeguarding
A SCADA system must continue to operate when field communications have failed.
The “ quality” of the data shown to the operator is an important part of the SCADA system operation.
SCADA systems often provide special “event” processing mechanisms to handle conditions which occur between data acquisitions periods.
5 MANAGEMENT LEVEL
SCADA Systems
Haward Technology Middle East 40Section 16
Process Control, Instrumentation and Safeguarding
SCADA Configuration
SCADA Systems
Haward Technology Middle East 41Section 16
Process Control, Instrumentation and Safeguarding
SCADA CONFIGURATION
SCADA Systems
Workstation
Workstation
RTU
RTU1
RTU2RTU N
Haward Technology Middle East 42Section 16
Process Control, Instrumentation and Safeguarding
SCADA CONFIGURATION
SCADA Systems
RTU1
RTU2
RTU3
RTU4
Server
Haward Technology Middle East 43Section 16
Process Control, Instrumentation and Safeguarding
SCADA CONFIGURATION
SCADA Systems