SCADA SYSTEMS: DESIGNING FOR RELIABILITY JONATHAN WHITE, PE FEBRUARY 16, 2016 WEAT FEBRUARY SEMINAR
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SCADASYSTEMS:DESIGNING FORRELIABILITY
JONATHAN WHITE, PEFEBRUARY 16, 2016
WEATFEBRUARY SEMINAR
A reliable SCADA system isachieved by…
1
2
3
Providing redundancy at single points of failure
Enhancing reliability of communications systems
Mitigating adverse environmental conditions
IntegratedControl Systems
Instrumentation
Reliable SCADA systems require acomprehensive design approach
SCADA System
Reliable SCADA systems require acomprehensive design approach
SCADA System
Process Design
Electrical Design
Programming Design
CommunicationsSystems Design
HVAC Design
A reliable SCADA system isachieved by…
1
2
3
Providing redundancy at single points of failure
Enhancing reliability of communications systems
Mitigating adverse environmental conditions
Redundant methods can eliminatesingle points of failure
Controller VFDRemoteTelemetry
Wetwell
ControlPanel
Redundant methods can eliminatesingle points of failure
Wetwell
ControlPanel
Controller VFDRemoteTelemetry VFD
Redundant methods can eliminatesingle points of failure
Wetwell
ControlPanel
Controller VFDRemoteTelemetry VFD
Redundant methods can eliminatesingle points of failure
BackupRelay
Control
Wetwell
ControlPanel
Controller VFDRemoteTelemetry VFD
Redundant methods can eliminatesingle points of failure
Cellular
BackupRelay
Control
Wetwell
ControlPanel
Controller VFDRemoteTelemetry VFD
Redundant controllers protect againstfailures with a centralized approach
PrimaryPLC
Remote I/O PanelHeadworks
Remote I/O PanelAeration Basins
Remote I/O PanelRAS/WAS
Main Control Building
Primary Server
Redundant controllers protect againstfailures with a centralized approach
PrimaryPLC
SecondaryPLC
Redundant crossload
Remote I/O PanelHeadworks
Remote I/O PanelAeration Basins
Remote I/O PanelRAS/WAS
Main Control Building
Primary Server
Sec. Server
Distributed control approacheliminates single point of failure
Standalone PLC PanelHeadworks
Main Control Building
Standalone PLC PanelAeration Basins
Standalone PLC PanelRAS/WAS
SCADA Server
Typical configurations only allowone path of communication
PrimaryPLC
SecondaryPLC
Redundant crossload
Remote I/O PanelHeadworks
Remote I/O PanelAeration Basins
Remote I/O PanelRAS/WAS
Main Control Building
RAS/WASSPOF
Ring configurations allow datato travel multiple ways
PrimaryPLC
SecondaryPLC
Redundant crossload
Remote I/O PanelHeadworks
Remote I/O PanelAeration Basins
Remote I/O PanelRAS/WAS
Main Control Building
Self Healing Ring
Backup power is necessary tomaintain system control
STANDBYGENERATOR
UPS
1hour
10 seconds –24 hours
OUTAGE LENGTH
Critical timewithout power as
generator kicks on
Redundant control executedat WWTP
Redundant PLCs &SCADA Servers
17 MGDWWTP
Local PLCs and RIOPanels
Ring NetworkConfiguration
11
2
3
2
2
2
2
2
3
A robust SCADA system isachieved by…
1
2
3
Providing redundancy at single points of failure
Enhancing reliability of communications systems
Mitigating adverse environmental conditions
Remote communication networksprovide variable reliability
Dedicated fiber optic
Radio telemetry
Broadband
Cellular
MOSTRELIABLE
LEASTRELIABLE
MOST CRITICALSCADA OPERATIONS
LEAST CRITICALSCADA OPERATIONS
Radio telemetry reliabilitydepends on:
• Grounding is very important• Surge protection at multiple
levels
LightningProtection
• Signal buffer at receiving end• 20dB recommended• Atmospheric conditions• Keep coax lengths short
FadeMargin
• Only transmit what is needed• Slower rate = fewer errorsData Rate
Remote communicationprovides secondary control
REMOTESECONDARY
SCADAWork station
RADIO RADIO
LOCALPRIMARY
PLC
A robust SCADA system isachieved by…
1
2
3
Providing redundancy at single points of failure
Enhancing reliability of communications systems
Mitigating adverse environmental conditions
Environmental conditionsaffect control reliability
Ideal Adverse
Relia
bilit
y
Environmental Conditions
High
Low
Proper cooling increasesexpected life
0
30,000
60,000
90,000
104 122 140 158 176
Life
in H
ours
Temperature in °F
10 Years
Variable Frequency DriveLife Expectancy
5 Years
Panel protection extends lifeexpectancy
Type 1 Type 12 Type 3R Type 4X Type 7
Ingressof dirt
Dirt, lightsplashing
water
Rain, snow,and sleet
Rain, snow,sleet,
hosedownwater,
corrosiveagents
ExplosionProof
Hazardouslocations
Cost
Comprehensive design approachcreates SCADA system reliability
Provides redundancy at single points of failure
Enhances reliability of communications systems
Mitigates adverse environmental conditions
1
2
3
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