Faulted Circuit Indicators Application Overview · PDF file · 2017-06-01Faulted...
Transcript of Faulted Circuit Indicators Application Overview · PDF file · 2017-06-01Faulted...
Faulted Circuit Indicators Application Overview
Anthony PatenaudeApplication Engineer I - FIS
Schweitzer Engineering Labs
Locating Distribution FeederFaults Is Challenging
Operating Voltages
System Voltage Levels
Transmission 765 kV, 500 kV, 345 kV, 230 kV,169 kV, 138 kV, 115 kV
Subtransmission 138 kV, 115 kV, 69 kV, 33 kV, 27 kV
Primary distribution 33 kV, 27 kV, 13.8 kV, 4 kV
Secondary distribution 120/240 V, 120/208 V, 240/480 V
FCIs Reduce Outage Time
Line Truck
What Are FCIs and How Do They Work?
Theory of Operation
• Sensor detects fault current greater than system load
• Larger amount of current flowing through conductor increases magnetic field
• FCI triggers display
I
B
–
+
Sensor and Display
• FCI has two main components♦ Sensing unit
♦ Display
• Display is integral or remote
• Remote display allows indication from a distance
Fixed Trip-Level FCIs
300
Time (Cycles)
40 A load
FCI trips when current exceeds trip rating and response time
500 A fault
5000
1 2 3
1.5 cycles
Operating Energy
• Line powered♦ Current and/or voltage
• Battery powered♦ Microprocessor based
♦ Timed reset (typical)
♦ LED products
• Fault powered – no arming quantity necessary
Backfeed Protection
• Back-feed currents can cause false tripping
• Backfeed protection option provides immunity from back-feed current surges faster than 24ms
• Sources of back-feed♦ Capacitor banks
♦ Motor spin down
♦ Inductive loads
• Back-feed and discharge currents can cause
♦ False trips (over tripping)
♦ False reset
SOURCE CAPBANK
Backfeed Protection
• Backfeed protection provides immunity from back-feed current surges faster than 1.5 cycles♦ Prevents false trips (over tripping)
♦ Prevents false reset
SOURCE CAPBANK
Backfeed Protection
Advanced Fault Detection Using CT and Microprocessor
• Load current measurement algorithms
• Auto-adjusting trip ratings
• More dynamic FCIs
• Single self-configuring unit placed across entire system
Applications - Overhead
Application
• Single- and three-phase overhead conductors
• Midfeeder disconnect
• Unfused taps
• Underground transitions♦ Dips
♦ Risers
Feeder Exit Riser Pole
Dead-End Riser
Underground FeederSubstation
Quickly Determine Overhead Versus Underground Fault
Dead-End Riser
Underground FeederSubstation
Closer Look at Fault in
Underground Cable
SourceSide
LoadSide
FCI identifieswhether fault is in
underground section or on overhead
system downstream
SourceSide
LoadSide
FCI identifieswhether fault is in
underground section or on overhead
system downstream
Closer Look at Fault in Overhead Conductor
Installation
Reference “A”: Maximum recommended distance from pole of 6’-0”
Reference “B”: Minimum distance from pole of 3’-0”
Reference “C”: Minimum distance from energized hardware of 2’-0”
Minimum Installation Spacing Requirements
Inrush Restraint Mechanism
Example #1: Recloser Lock-out / Fault Downstream of FCIs
• Downstream fault – low impedance♦ Assume a 13.2 kV L-L system
– Line has been energized long enough to power up / arm the FCIs
– FCIs downstream of a 3 phase sectionalizing automatic recloser
To Source
To Load
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Time
Example #1: Recloser Lock-out / Fault Downstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Fault
Time
Example #1: Recloser Lock-out / Fault Downstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Recloser operates
Time
Fault
Example #1: Recloser Lock-out / Fault Downstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
TimeInrush Restraint Activated
Fault Recloser operates
Example #1: Recloser Lock-out / Fault Downstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Time
Recloser closes back inFault Recloser
operates
Inrush Restraint Activated
Example #1: Recloser Lock-out / Fault Downstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Time
Fault Recloser operates
Recloser closes back in
Inrush Restraint Activated
Example #1: Recloser Lock-out / Fault Downstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Time
Fault Recloser operates
Recloser closes back in
Recloser Lock‐out
Recloser Lock‐out
Inrush Restraint Activated
Example #1: Recloser Lock-out / Fault Downstream of FCIs
Example #2: Recloser Lock-out / Fault Upstream of FCIs
• Upstream fault – low impedance♦ Assume a 13.2 kV L-L system
– Line has been energized long enough to power up / arm the FCIs
– FCIs downstream of a 3 phase sectionalizing automatic recloser
To Source
To Load
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Time
Example #2: Recloser Lock-out / Fault Upstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Time
Example #2: Recloser Lock-out / Fault Upstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
Time
Example #2: Recloser Lock-out / Fault Upstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
TimeInrush Restraint Activated
Example #2: Recloser Lock-out / Fault Upstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
TimeInrush Restraint Activated
Example #2: Recloser Lock-out / Fault Upstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
TimeInrush Restraint Activated
Example #2: Recloser Lock-out / Fault Upstream of FCIs
Trip Rating
Load
Trip Rating
Load
B&C Phases
A Phase
TimeInrush Restraint Activated
Recloser Lock‐out
Recloser Lock‐out
Example #2: Recloser Lock-out / Fault Upstream of FCIs
Applications - Underground
Live-Front Switchgear Air insulated
Cables terminated to exposed live bus
Cable termination uses voltage stress relief
No test point availability
Not applicable in subsurface applications
Install FCI units below stress relief
Install FCI with Snap-Action clamp onto terminal lug
Three-Phase Live-Front Switchgear
Four-Way Switch
Install FCIs at unfused outgoing feeds
Side view Top-down view
3 2
14IN
Dead-Front Switchgear Designed with no exposed high-voltage parts
Pad-mount and subsurface applications
Uses standard connector system interface (Elbows & T-Bodies)
Connectors are shielded with semi-conductive rubber outer surface
Likely that test points are available
Three-Phase Switchgear
Three-Phase Switchgear
Three-Phase Switchgear
LOAD
SIDE
Concentric Neutral Training
Four Acceptable Options• Double Backed
• Braided
• Pulled Back (drain wire inside core)
• Pulled Back (drain wire outside of core)
Tape-Shielded Cable and Adapter
Fault Indicators Are a Good Value
• Meet needs of a large-scale deployment♦ Easy to Install
♦ Low cost
♦ Little to no maintenance
♦ Long service life (10+ years minimum)
• Reduce fault finding time by half
• Easy to spot and determine status in field
Thank You for Your Time!Any Questions?