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?