Upload
kelley-perry
View
213
Download
0
Embed Size (px)
Citation preview
SWEDE - April 26th, 2011 - BastropTommy Nylec
Austin Energy Fusing and Fault Austin Energy Fusing and Fault Indicator ApplicationsIndicator Applications
Austin Energy Fusing and Fault Austin Energy Fusing and Fault Indicator ApplicationsIndicator Applications
2 2
OverviewOverviewOverviewOverview
Introduction to Austin Energy Purpose of Coordination Concern
Unique Situations Engineering and Operational Solutions
Future Work and Conclusions
3 3
Austin Energy StatisticsAustin Energy StatisticsAustin Energy StatisticsAustin Energy Statistics
>400,000 Customers >2,800 MW Generation ># mi Transmission 56 Distribution
Substations > 10,000 miles of
Distribution >1,600 Employees Serve 437 square miles
including Austin city limits and neighboring areas
Started in 1887
4 4
Austin Energy ReliabilityAustin Energy ReliabilityAustin Energy ReliabilityAustin Energy Reliability
SAIFI = .63 SAIDI = 43.97 CAIDI = 69.86 Challenge ourselves
with high goals for reliability indices
Consistently in the top performance in the country
5 5
Coordination Scheme RevisitedCoordination Scheme RevisitedCoordination Scheme RevisitedCoordination Scheme Revisited
Need to be simple to interpret for field personnel Must allow for ease of use in design environment Application must hold in > 80% cases Point of coordination determined by maximum
available fault current 20% Separation between Total Clear and
Minimum Melt curves of devices
6 6
Austin Energy Fault Current LevelsAustin Energy Fault Current LevelsAustin Energy Fault Current LevelsAustin Energy Fault Current Levels
Item of Concern Infinite Bus Calculations for
Larger Transformers= 14.5 kA Short Feeders High density of substations System is primarily 12.5 kV Transmission Impedance on
larger transformers creates approximately 10 kA
Majority of fuses are at > 2kA Typical Unit Installation
results in Fault Current < 8.5 kA at Bus
7 7
Warehouse InventoryWarehouse InventoryWarehouse InventoryWarehouse Inventory
Limited space in warehouse and trucks Minimize variety of fuses Standardize applications
Reduction of inventory
8 8
Substation CoordinationSubstation CoordinationSubstation CoordinationSubstation Coordination
Most relays set at 360 A Ground Pickup Eases coordination with downstream devices Provides adequate system protection
Considerations Some substations do not have this setting Conflicts with some fusing scenarios
9 9
Unique ScenariosUnique ScenariosUnique ScenariosUnique Scenarios
Slugging Required due to
presence of extra fuse
Fault Level Cheat Sheets
Rules of Thumb don’t apply Skip fuse size between
devices
10 10
SolutionSolutionSolutionSolution
Keep same fuse ampacity ratings
Limit number of fuses with same ampacity but different speeds Allow duplicates in most
common sizes
Austin Energy Rule of Thumb Must skip 2 fuse sizes between
devices
11 11
Feeder Coordination StudiesFeeder Coordination StudiesFeeder Coordination StudiesFeeder Coordination Studies
Studies performed on 5 year rotational basis Creates opportunity to revisit coordination
scheme Allows adjustment of existing fuses to new
scheme Limited inventory restricts solutions to
encountered problems
12 12
Fault Indicator ApplicationFault Indicator ApplicationFault Indicator ApplicationFault Indicator Application
Fault must pass through equipment
Placed accordingly Follow Cooper
Application guide
13 13
Austin Energy StandardAustin Energy StandardAustin Energy StandardAustin Energy Standard
Traditional Placement: Located at
transformer
Austin Energy Additional Requirements: Additional F.I.’s
located at risers and switchgears
14 14
Installation MethodsInstallation MethodsInstallation MethodsInstallation Methods
Concentric Neutral Identified
misapplication Changes made to
standard to correct In accordance with
industry standards
15 15
Fault Indicator ConclusionsFault Indicator ConclusionsFault Indicator ConclusionsFault Indicator Conclusions
Provide additional visual cues of fault locations
Decrease service restoration time Reduce equipment exposure during
restoration practices Economic Impact
16 16
Questions?Questions?Questions?Questions?