1. SCADA, what can it do for you?
Tim Sawtelle, P.E.
Dirigo Engineering
(207)
John Murray
Control Point, Inc.
(207)

2. SCADA A review OF THE Purpose and BASIC functions of SCADA systems for
Water and WASTEWATER systems.
Things to be aware of as you plan
the installation or upgrade of
your SCADA system.

3. Definition of SCADA “Supervisory Control And Data Acquisition”
Computer controlled system that monitors, controls and records industrial or utility processes.
Implications
Supervisory Control  Big Picture
set parameters for control
monitor performance
Programable Electronic Controllers
Usually involves communication with remote site(s)
Data is displayed and recorded on a PC

4. SCADA System

5. SCADA Software

6. SCADA System vs. SCADA Software
SCADA System – The entire system including master station, remotes, instrumentation, communication systems and the SCADA software.
SCADA Software – The software package that normally resides on the primary SCADA PC at the master station.

7. SCADA Software Database running on one or more PCs Data
Usually one PC at the master PLC
Graphical representation of system
Collects and records data and handles alarm annunciation
HMI Functions plus unlimited recording
Data
Analog trends, discrete trends/histories
Alarm histories
SQL or other formats, data can be exported

11. Statistical Process Control (SPC) information

14. Mobile Web Thin Clients Plant PLC and Remote I/O
Monitor the Process
SCADA Station
Internet
(ISP)
Mobile Web Thin Clients
(Web-browser)
Plant PLC and Remote I/O
Manage Events and Alarms

15. SCADA Software Tags or Points
List of values used in the SCADA system/software
Real world I/O
Setpoints
Status of Discretes
Calculated Values
Totals, etc.
WATER
WIZARD

16. HMI “Human-Machine Interface”.
Displays process data for the operator (M to H)
Allows operator access to change/control the process (H to M)
HMI is usually referring to a keypad/display or touch-screen panel located at a remote site or in the “plant”.
HMI is sometimes used to refer to SCADA Software.
An alternative term – Operator Interface Terminal (OIT)

17. HMI

18. Telemetry
A system that automatically transmits measurements from remote locations.
tele = far
metron = measure
Includes:
Sensor(s)
Transmission/Reception
Radio/Telephone/Network/Cellular
Display/Record/Control

19. RTU Remote Terminal Unit or Remote Telemetry Unit
A microprocessor controlled device that interfaces with the station or plant. The RTU sometimes controls the local equipment, sometimes includes an OIT/HMI and usually communicates with the master station.
Package (integrated) device, proprietary
Emphasis on data transmission not programmable control

20. RTUs

21. Typical Remote Site

22. Programmable Logic Controller.
PLC
Programmable Logic Controller.
A microprocessor based device that interfaces with instruments and equipment at the facility and provides for control and communications.
Often is connected to an OIT/HMI
Communicates with master
Programmable for local/distributed control
Usually uses relay ladder logic
And, or, not, Boolean Statements, math calculations, etc.
If it can be put in words it can probably be put in RLL
Interface with local facility inputs and outputs (I/O)
Analog I/O & Discrete I/O

23. I/O Field Inputs & Outputs
Discrete Inputs (on/off contact closures, relays)
Examples – a pump is running, a float is up, switch position
Discrete Outputs (energize a relay coil)
Examples – tell a pump to start, turn on an alarm light
Analog Inputs
Examples – flow meter reading, chlorine residual reading
Analog Outputs
Examples – send a speed to a VFD, send a SPM signal to a chemical pump

24. Typical Analog Input Field Instrument
Measures parameter & displays on instrument
Produces a DC voltage or current proportional to the signal
4-20 mA
PLC reads the analog input and converts it to digital real world units for display on OIT and use in local control decisions
Digital value can also to transmitted to master station

25. Some “words” about PLCs
PLC data storage and communication is measured in “words”.
1 word = 1 numeric value
1 word = 16 statuses
Typical communication with remotes
Simple station 1-5 words
Complex station words
Typical radio transmission rate using serial = 600 words/sec.

26. Communication Wireless Data Transmission (serial and/or IP)
VHF (150 MHz), requires FCC license
UHF (450 MHz), requires FCC license
900+ MHz, spread spectrum
Cellular
Satellite
Wired Data Transmission
Phone
leased line or PSTN (dialup)
Private Line Network
Internet

27. Wireless Communication
Wireless Communication Components
Communication Port & Cabling
Radio/Modem
Speed, “words”/minute
Transmission System
Antenna
Path(s)
Schedule (polling)

28. Radio Communications
Store and Forward #2 #3 #4 #1

29. Cellular Communications

30. Control Methods Manual Semi-Auto Automatic
Visual observations, manual switches, manual form
………
Semi-Auto
Adjustable Switches & Time Clocks
Instruments with control/alarm setpoints
Chart Recorders (with setpoints/ relay outputs)
Automatic
SCADA with programmable control

31. Local/Distributed Control
To the greatest extent possible individual control decisions are made at the remote site by the PLC
Example –transmit tank level to remote station vs. transmit a request for pump run to remote station
Assumes proper design of hydraulic and control system.
Need proper interlocks for safety and protection.
Automatic procedures at remote with loss of communication.
Design controls to function as well as possible even if communication is lost.

32. Emergency/Backup Control
Maintain “manual” operation capability
HOA Switches with “Hand” outside PLC
Visual feedback; pressure gauge, etc.
Backup controls where possible
High/High and/or Low/Low Floats
High/High and Low/Low Pressure Switches, etc.
Advantages of VFDs
Start and stop gently
Short cycles are less problematic

33. Startup/ Testing At Startup During Operation Periodically
Ring out all the I/O
Test/ prove every procedure
During Operation
Be familiar with “normal” operation
What lights are on/off or flashing, etc.
Is it acting normal and as you expect it to?
Note any unusual operation
Periodically
Test critical interlocks/ alarms

34. License Class Requirements
Is a water or sewer utility with a SCADA system more difficult or complicated to operate than a utility without a SCADA system?

35. Top 5 SCADA Security Threats per SynergistSCADA
Inability to easily detect anomalous activity
Installing inappropriate applications on critical SCADA host computers
Unauthenticated PLC / Remote Site network connections
The false belief that SCADA systems have the benefit of security through obscurity due to the use of specialized protocols and proprietary interfaces
The belief that SCADA networks are secure because they are not connected to the Internet

36. SCADA Security Threats
Building and equipment security
Entry control, locks, passwords, etc.
Unauthorized employees or former employees
Multi-level passwords, etc.
Communications & Network Security

37. SCADA Security Threats

38. SCADA Security Threats
The “Isolation” Philosophy
Plug into Power & PLC only
No Internet No
No installations allowed
No other software
No thumb drives, etc.
Dedicated backup

39. SCADA Security Threats
Reasonable approach for semi-obscure systems?
Dedicated SCADA PC, no other uses allowed
Firewall
Internet Security Software
Very limited web access, no reception
Send only from SCADA
If use remote access, utilize VPN

40. Worker Safety Comply with OSHA, DOL and NEC requirements.
Arc Flash, Lockout/Tagout, etc.
Utilize panel interface port to eliminate opening panels for programming.

41. Variations on the theme
SCADA is a rapidly evolving technology
Computer & Software Developments
Communications Innovations
We only introduced some of the more common equipment and software possibilities.
There is almost unlimited software choices and add on software products for alarm-notification, reporting and other features.
Also, almost unlimited hardware choices and manuf.

42. SCADA, what can it do for you?
Tim Sawtelle, P.E.
Dirigo Engineering
(207)
John Murray
Control Point, Inc.
(207)