8/10/2019 ICC Fall 2010 ICC Education Session (1)
1/59
1
Fall 2010 ICC Education Session
ICC Education Session
Cable Accessory Failure Analysis
F. Dean Williams
Fall 2010 Meeting
8/10/2019 ICC Fall 2010 ICC Education Session (1)
2/59
2
Fall 2010 ICC Education Session
Outline
Background
Overall Process for an Effective Forensic Program Primary Modes of Failure
Benefits of a Forensic Program
Summary
8/10/2019 ICC Fall 2010 ICC Education Session (1)
3/59
3
Fall 2010 ICC Education Session
Background Significance of Problem
OldMiddle AgedNew
80
70
60
50
40
30
20
10
0OldMiddle AgedNew
Accessories
Age Description
PercentageofServiceInteruptions(%
)CableCable accessories have a significant
Infant mortality rateNewly installed accessories account
for 20% of accessory related service
interruptions
Workmanship is the Number 1 cause
of failure representing nearly 50% ofthe total failures
The number of unknown cause of
failure is high (about 20%) showing the
need for more thorough forensic
evaluations
Manufacturing defects represent 15%
of the total failures
8/10/2019 ICC Fall 2010 ICC Education Session (1)
4/59
4
Fall 2010 ICC Education Session
Analysis of Collated Data Cable Accessories -Cause of Failure
Faul t Type
0
510
15
20
25
30
35
40
Poor
workm
anship
Manuf
actu
ringproblem
Corro
sion
Mecha
nical
Dam
ageEv
ent
Aging
Overloa
d
Unkn
own
Moist
ure
Othe
r
Dielectric
breakd
own
Contamina
tion
Overhe
at
Incorre
ctrecord
Mainten
ance
failu
re
%o
fTotalCases
8/10/2019 ICC Fall 2010 ICC Education Session (1)
5/59
5
Fall 2010 ICC Education Session
Analysis of Collated Data Failures by AccessoryVintage
Accessory Vintages - All Utilities
0
5
10
15
20
25
30
35
40
1970-1975
1975-19
80
1980-19
85
1985-19
90
1990-19
95
1995-20
00
2000-20
05
>2005
Vintage
%o
fTota
lFailures
Joints Terminations Junctions
8/10/2019 ICC Fall 2010 ICC Education Session (1)
6/59
6
Fall 2010 ICC Education Session
Analysis of Collated Data Cause of Failure
SummarybyFailureTypeAllUtilities
Overheat
4%
Dielectric
breakdown
10%
Aging
6%
Corrosion
4%
Moisture
4%
Event
3%
Manufacturing
problem
14%
Overload
2%
Maintenancefailure
2% Mechanical Damage
1%Contamination
1%
Poor
workmanship
49%
8/10/2019 ICC Fall 2010 ICC Education Session (1)
7/59
7
Fall 2010 ICC Education Session
Overall Process for an EffectiveForensic Program
Preservation of sample integrity
Importance of sister components
Collection of background information
Obtain installation instructions
Choose the right evaluation technique/document all findings Identify all installation errors/determine most probable root cause of
failure
Clearly and accurately report all findings/forward to the appropriate
personnel Track results of examinations
8/10/2019 ICC Fall 2010 ICC Education Session (1)
8/59
8
Fall 2010 ICC Education Session
Preservation of Sample Integrity
Remove sufficient cable length on either side of failedcomponent
Label sample to clearly identify location of failure
Seal cable ends and wrap component to protect from
environment
Keep associated components together
Store in a dry location prior to performing analysis
8/10/2019 ICC Fall 2010 ICC Education Session (1)
9/59
9
Fall 2010 ICC Education Session
Preservation of Sample Integrity
If you do not know what you are doing Do Not attempt
your own analysis
8/10/2019 ICC Fall 2010 ICC Education Session (1)
10/59
10
Fall 2010 ICC Education Session
Importance of Sister Components
Sister components are those installed at
the same time of the failed component,
likely by the same installer
Significant damage to failed component
may prevent determining most probable
root cause of failure
Sister components allow for easy
detection of installation/workmanship
errors if installed by the same personnel
8/10/2019 ICC Fall 2010 ICC Education Session (1)
11/59
11
Fall 2010 ICC Education Session
Sister Units
JacketCutback
Constant Force Spring
Ground Strap
Copper Tape
Shield
Jacket
Cutback
8/10/2019 ICC Fall 2010 ICC Education Session (1)
12/59
12
Fall 2010 ICC Education Session
Sister Units
Cut in Cable Insulation at
Jacket Cutback
8/10/2019 ICC Fall 2010 ICC Education Session (1)
13/59
13
Fall 2010 ICC Education Session
Sister Units
Cut in Tape Shield
at Jacket Cutback
Copper Tape
Shield intact
8/10/2019 ICC Fall 2010 ICC Education Session (1)
14/59
14
Fall 2010 ICC Education Session
Collection of Background Information
Events leading up to failure (weather, switching events,previous failures, etc.)
Circuit diagram
Number of re-closures on circuit after initial failure
Available fault current Typical loading conditions
Type of load being served
Any additional information that may be helpful indetermining the root cause of failure
8/10/2019 ICC Fall 2010 ICC Education Session (1)
15/59
15
Fall 2010 ICC Education Session
Obtain Installation Instructions
Obtain installation instructions for vintage of
component to be evaluated
A proper analysis of most failed components is the
exact reverse of the installation instructions
Check for function, not for detailed compliance
A perfectly installed accessory may fail by means
outside the installers control
8/10/2019 ICC Fall 2010 ICC Education Session (1)
16/59
16
Fall 2010 ICC Education Session
Outside the Installers Control
Termite
Damage
UV Aging
8/10/2019 ICC Fall 2010 ICC Education Session (1)
17/59
17
Fall 2010 ICC Education Session
Outside the Installers Control
12 Inches
Over inch
Total InsulationShrinkback
8/10/2019 ICC Fall 2010 ICC Education Session (1)
18/59
18
Fall 2010 ICC Education Session
Think before you cut
Document all findings/observations
through photographs
Preserve failure site, Do Not make
cuts directly through failure site
Cuts should be made at locations 90
degrees on either side of failure site
Cuts through failure site should only
be made, if necessary, and once a
detailed examination of the variousmating interfaces has been made
Choose the Right EvaluationTechnique
Failure Site
Cut through Failure
Site
8/10/2019 ICC Fall 2010 ICC Education Session (1)
19/59
19
Fall 2010 ICC Education Session
X-Ray
8/10/2019 ICC Fall 2010 ICC Education Session (1)
20/59
20
Fall 2010 ICC Education Session
Identify all Installation Errors/Determine
Most Probable Root Cause of Failure
Identification of all installation errors should be documented to
enhance training efforts
Multiple errors may have contributed to the failure
Determine most probable cause by process of elimination through a
detailed analysis of the available evidence
When you have eliminated the impossible, whatever remains, however
improbable, must be the truth
Sherlock Holmes In the Sign of the Four
8/10/2019 ICC Fall 2010 ICC Education Session (1)
21/59
21
Fall 2010 ICC Education Session
Clearly and Accurately Report allFindings
Report should indentify most
probable cause of failure and allinstallation errors observed
Share report with all parties to reduceor prevent future occurrences
Discuss product defects with
manufacturer to improve processes Discuss installation errors with
training personnel or installers toeliminate installation errors
If installation errors are the result of
unclear installation instructions reviseinstructions
As-Buil t of termination used in report
8/10/2019 ICC Fall 2010 ICC Education Session (1)
22/59
22
Fall 2010 ICC Education Session
Track Examination Results
Results of examinations should be tracked in a database
A database will help responsible personnel to observe and
take appropriate action when trends in installation errors
or manufacturing defects are evident
8/10/2019 ICC Fall 2010 ICC Education Session (1)
23/59
23
Fall 2010 ICC Education Session
Common Failure Modes
Workmanship
Manufacturing Defects
Design Issues
8/10/2019 ICC Fall 2010 ICC Education Session (1)
24/59
24
Fall 2010 ICC Education Session
Workmanship
Cut in CableInsulation
8/10/2019 ICC Fall 2010 ICC Education Session (1)
25/59
25
Fall 2010 ICC Education Session
Workmanship
Nicks in Conductor
StrandsCuts in Conductor
Strands
8/10/2019 ICC Fall 2010 ICC Education Session (1)
26/59
26
Fall 2010 ICC Education Session
Workmanship
Lower Cold Shrink Tube Incorrectly
Installed at Upper End of Termination
Black StressControl Tube
Electrical Activity off
Insulation Shield Cutback
8/10/2019 ICC Fall 2010 ICC Education Session (1)
27/59
27
Fall 2010 ICC Education Session
Workmanship
Incomplete Shrink Down of Dual
Layer Tube Leading to Failure
Puncture
8/10/2019 ICC Fall 2010 ICC Education Session (1)
28/59
28
Fall 2010 ICC Education Session
Workmanship
Discharge between Inner
Stress Control Tube and
Cable Insulation Caused by
Incomplete Shrink Down
8/10/2019 ICC Fall 2010 ICC Education Session (1)
29/59
29
Fall 2010 ICC Education Session
Workmanship
Discharge between Inner Stress ControlTube and Dual Layer Tube Caused by
Incomplete Shrink Down and Failure to
Keep Stress Control Tube Hot
8/10/2019 ICC Fall 2010 ICC Education Session (1)
30/59
30
Fall 2010 ICC Education Session
Workmanship
Corrosion
Deposits
Lack of Bond between
Mastic and Jacket
Water
Migrated
Past End
Seal
No Mastic between
Solder Blocks
8/10/2019 ICC Fall 2010 ICC Education Session (1)
31/59
31
Fall 2010 ICC Education Session
Workmanship
Discharge between
Stress Control
Tube and Insulation
Shield
Puncture at KnifeCut in Cable
Insulation
8/10/2019 ICC Fall 2010 ICC Education Session (1)
32/59
32
Fall 2010 ICC Education Session
Workmanship
Interface Tracking
from Surface
Contamination
8/10/2019 ICC Fall 2010 ICC Education Session (1)
33/59
33
Fall 2010 ICC Education Session
Workmanship
Water
Dirt Depositsand Lack of
Bond
8/10/2019 ICC Fall 2010 ICC Education Session (1)
34/59
34
Fall 2010 ICC Education Session
Workmanship
Contamination between InsulatingTube and Stress Control Tube
8/10/2019 ICC Fall 2010 ICC Education Session (1)
35/59
35
Fall 2010 ICC Education Session
Workmanship
Stress Relief Mastic Across
Entire Cable Interface
8/10/2019 ICC Fall 2010 ICC Education Session (1)
36/59
36
Fall 2010 ICC Education Session
WorkmanshipBrown Discoloration
of TRXLPE caused
by Overheating
CompressionConnector
No Wire Brush Marks on Conductor
in Area of Crimp Down
8/10/2019 ICC Fall 2010 ICC Education Session (1)
37/59
37
Fall 2010 ICC Education Session
WorkmanshipDeformation of
Insulation
Transition of Insulation Color
Away from Connector
Thermal
Damage to
Joint Body
8/10/2019 ICC Fall 2010 ICC Education Session (1)
38/59
8/10/2019 ICC Fall 2010 ICC Education Session (1)
39/59
39
Fall 2010 ICC Education Session
Workmanship
Brown Discoloration of
TRXLPE caused by
Overheating Compression
Connector
Thermal
Damage
Tool Cuts in
Conductor
Strands
8/10/2019 ICC Fall 2010 ICC Education Session (1)
40/59
40
Fall 2010 ICC Education Session
WorkmanshipAluminum
Oxides
Area of Crimpdown
in Connector Body
Arc Pit in
ConnectorBody
8/10/2019 ICC Fall 2010 ICC Education Session (1)
41/59
41Fall 2010 ICC Education Session
Workmanship
Bent
Probe
Melting of Arc
Quenching
Probe
8/10/2019 ICC Fall 2010 ICC Education Session (1)
42/59
42Fall 2010 ICC Education Session
Workmanship
Surface
Tracking
Surface
Contamination
8/10/2019 ICC Fall 2010 ICC Education Session (1)
43/59
43Fall 2010 ICC Education Session
Workmanship
Corrosion
Deposits
Ground
Strap
Soldier Block Located over Dual
Layer Tube
8/10/2019 ICC Fall 2010 ICC Education Session (1)
44/59
44Fall 2010 ICC Education Session
Workmanship
Cut in Cable
Insulation
Dielectric
Puncture
Start of Penciling on Cable Insulation
Thin Area of Insulation Wall In Line
With Failure
8/10/2019 ICC Fall 2010 ICC Education Session (1)
45/59
45Fall 2010 ICC Education Session
Workmanship
Note that Cut Al igns with
Centerline of Puncture
Electrical
Treeing
Fault
Channel
8/10/2019 ICC Fall 2010 ICC Education Session (1)
46/59
46Fall 2010 ICC Education Session
WorkmanshipFailure
Site
Open Neutrals Arcing
to Bracket
Bracket Cutting into
Cable
8/10/2019 ICC Fall 2010 ICC Education Session (1)
47/59
47Fall 2010 ICC Education Session
Workmanship
Compression Lug
Vaporized
8/10/2019 ICC Fall 2010 ICC Education Session (1)
48/59
48Fall 2010 ICC Education Session
Workmanship/Manufacturing
Knife Cuts Created During
removal of Joint Body
Sanding
Marks
Folds/Wrinkles in
Copper Tape
White
Bedding Tape
8/10/2019 ICC Fall 2010 ICC Education Session (1)
49/59
49Fall 2010 ICC Education Session
Manufacturing Defect
Puncture Site
Area of
Discoloration
Puncture Site
8/10/2019 ICC Fall 2010 ICC Education Session (1)
50/59
50Fall 2010 ICC Education Session
Manufacturing Defect
Insulation
Conductor
Shield
Puncture in
Conductor
Shield
Void in
Insulation
8/10/2019 ICC Fall 2010 ICC Education Session (1)
51/59
51Fall 2010 ICC Education Session
Manufacturing DefectFault
Channel in
Joint
Insulation
Metal
Contaminant
8/10/2019 ICC Fall 2010 ICC Education Session (1)
52/59
52Fall 2010 ICC Education Session
Design Issues
Surface Trackingon Cable
Insulation
Erosion of Stress
Control Tube
8/10/2019 ICC Fall 2010 ICC Education Session (1)
53/59
53Fall 2010 ICC Education Session
Design Issues
Corrosion on
Conductor
Path of MoistureMoisture Entry
Point
8/10/2019 ICC Fall 2010 ICC Education Session (1)
54/59
54Fall 2010 ICC Education Session
Design Issue
Dielectric
Puncture
Cable
Training
8/10/2019 ICC Fall 2010 ICC Education Session (1)
55/59
55Fall 2010 ICC Education Session
Design IssueComplete Break in
Sheath
Stress Cracking
Failure Site
8/10/2019 ICC Fall 2010 ICC Education Session (1)
56/59
56Fall 2010 ICC Education Session
Design Issue - UV AgingSurface Tracking and
Erosion
Stress
Cracking
8/10/2019 ICC Fall 2010 ICC Education Session (1)
57/59
57Fall 2010 ICC Education Session
Benefits of a Failure Analysis Program
Improve Training
Reduce outages
Increase in revenue
Reduce need for expensive diagnostic testing
8/10/2019 ICC Fall 2010 ICC Education Session (1)
58/59
58Fall 2010 ICC Education Session
Summary Surveys and data analysis show
cable accessory failures make up a
large percentage of in-serviceoutages
About 20% of accessory failures
have no known cause, indicating a
need for more detailed forensic
analysis About 15% of accessory failures
can be attributed to manufacturing
defects, indicating a need for
tighter control of manufacturing
processes Surveys and data analysis show
the need for improved training of
cable accessory installers
Unknown1.1%Terminations
5.6%
Splices37.1%
Cable56.2%
Utility Survey Showing System Failure Causes
8/10/2019 ICC Fall 2010 ICC Education Session (1)
59/59
59Fall 2010 ICC Education Session
Summary
All evidence points to
improved TRAININGas the single most
cost effective
means of improvingsystem reliability
Top Related