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

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. SCADA

Definition of SCADA “ S upervisory C ontrol A nd D ata A cquisition”  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

SCADA System

SCADA Software

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.

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

Statistical Process Control (SPC) information

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

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

HMI “ H uman- M achine I nterface”.  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 – O perator I nterface T erminal (OIT)

HMI

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

RTU R emote T erminal U nit or R emote T elemetry U nit 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

RTUs

Typical Remote Site

PLC P rogrammable L ogic C ontroller.  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

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

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

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.

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

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

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

Cellular Communications

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

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.

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

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

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?

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

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

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

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

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

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.

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