Tim Sawtelle, P.E.

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SCADA, what can it do for you?

• Tim Sawtelle, P.E.
• Dirigo Engineering
• tim_at_dirigoeng.com
• [phone]

• John Murray
• Control Point, Inc.
• johnmurray_at_controlpt.com
• [phone]

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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.

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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

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SCADA System
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SCADA Software
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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.

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SCADA Software

• Database running on one or more PCs
• 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

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Statistical Process Control (SPC) information
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Monitor the Process
SCADA Station
Mobile Web Thin Clients (Web-browser)
Plant PLC and Remote I/O
Manage Events and Alarms
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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
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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)

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HMI
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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

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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

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RTUs
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Typical Remote Site
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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

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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

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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

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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 20-50 words
• Typical radio transmission rate using serial
  600 words/sec.

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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

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Wireless Communication

• Wireless Communication Components
• Communication Port Cabling
• Radio/Modem
• Speed, words/minute
• Transmission System
• Antenna
• Path(s)
• Schedule (polling)

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Radio Communications
Store and Forward
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4
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Cellular Communications
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Control Methods

• Manual
• 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

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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.

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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

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Startup/ Testing

• At Startup
• 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

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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?

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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

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SCADA Security Threats

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

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SCADA Security Threats
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SCADA Security Threats

• The Isolation Philosophy
• Plug into Power PLC only
• No Internet
• No email
• No installations allowed
• No other software
• No thumb drives, etc.
• Dedicated backup

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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 email reception
• Send email only from SCADA
• If use remote access, utilize VPN

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Worker Safety

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

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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.

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SCADA, what can it do for you?

• Tim Sawtelle, P.E.
• Dirigo Engineering
• tim_at_dirigoeng.com
• [phone]

• John Murray
• Control Point, Inc.
• johnmurray_at_controlpt.com
• [phone]