ICC Educational Programs
Officers:
Chair: Sudhakar Cherukupalli, BC Hydro,
Sudhakar.Cherukupalli@bchydro.bc.ca
Vice Chair: Dr. Carol Liu, American Electric Power,
xcliu@aep.com,
614-836-4263
Educational Programs conducted at ICC meetings are a great way to learn
new skills or brush up on old ones. Presented by individuals who are truly leaders in our
field, the Educational Program is always a hit. Beginning in the Fall of 1999, the ICC
began to issue Certificates of Attendance and PDH (Professional Development Hours)
credit for attending the ICC Educational Program.
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Fall 2007- Nuclear Power Plant Cables |
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Spring 2007- Cable Ampacity |
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Fall 2006- Impact of Hurricanes on Electric Grid Infrastructure –
System Recovery, Restoration and Preparedness |
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Spring 2006-
Integration of a New HV cable System in the Network – Technical and
Environmental Issues ; given by CIGRE |
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| Fall 2005 -
EPR Insulated Cable |
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| Spring 2005 -
Secondary Cable Technology |
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| Fall 2004 -
Statistical Analysis of UD Cable Failures |
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| Spring 2004 - IREQ Lab Tour
(photos
from the tour) |
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| Fall 2003 -
High Voltage Cables |
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| Spring 2003 -
An Overview of PILC Cables |
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| Fall 2002 - URD Cable Design, Past, Present and Future |
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| Spring 2002 - Accelerated Cable Testing
and Its Correlation to Field Testing |
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| Fall 2001 - Basic Power Cable Design, Part
II |
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| Spring 2001 - An Overview of Diagnostic
Testing of Medium Voltage Power Cables (Non-PD Methodologies) |
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| Fall 2000 - Partial Discharge Testing |
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| Spring 2000 - Basic Power Cable Design |
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| Fall 1999 - Design Principles for
Cable Accessories (Separable Connectors, Joints and Terminations)
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| Fall 2005 Educational Program -
EPR Insulation & Cables
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Evolution of EPR Compounding (3.6 MB
PDF)
Carl Zuidema, The Okonite Company
Abstract: There are four elastomeric materials that have found widespread use
as the primary dielectric in wire and cable for power delivery:
cis-polyisoprene, (natural rubber), polybutadiene co-styrene - (SBR),
polyisobutylene co-isoprene - (IIRR) polyethene co-propene - (EPR). The art of
rubber compounding began with the invention of vulcanization of natural rubber
by Charles Goodyear in 1844. This talk will focus on the development of rubber
technology as applied to the dielectric of electrical wire and cables. We will
briefly review the development of natural rubber compounds, the invention of
synthetic rubber and the particular compounding requirements of each of these.
An emphasis will be placed on the relationship between polymer structure and
physical properties, as well as the relationship between compounding
variations and finished properties. This leads to a discussion of the
different types of EPR compounds, defined by the ICEA as classes I, II, III
and IV. Manufacturing methods for mixing and processing EPR will be reviewed.
Lastly we will discuss semi-conducting EPR compounds as used for cable
shields.
- Q: John Rector, Black & Veach – How dependent
are different cable designs on EPR compounds and what makes EPR not
suitable, say for wet design
A: EPR’s are good for wet cable designs and the fillers in the insulation
compound are critical for its suitability for wet designs; if the fillers
are altered it may make them not suitable
- Q: Rick Hartlein, Neetrac – Are butyl rubbers
Type I rubber; it will be good to have reference(s) where its
characteristics are described
A: Yes the butyl rubbers are Type I with poorer mechanical properties;
useful references will be added to the slides. (The slides are revised to
include general references for further reading on rubbers)
- Q: Carlos Katz, Cable Technology Laboratories –
In the case of semiconducting EPR, are the fillers replaced 100% or less
by carbon black?
A: It depends on the conductivity of the carbon black; for example more
than 100% replacement may be required if lower conducting black is used
- Q: Ajit Hiranandani, DTE – Is chemical treeing
mechanism in EPR different from that in XLPE?
A: Treeing is not a recognized mode of failure in EPR and hence not as
extensively studied as in the case of XLPE
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Black EPR (63 KB PDF)
Ronald F. Frank, Cable Engineering Consultant
Abstract: Data is presented on 5kV to 46kV shielded cable insulated with black
EPR made by one cable manufacturer from 1964 to 1970. To achieve maximum
performance characteristics at this time a small amount of carbon black was
added to the EPR compound, which gave it a black color. Service experience
with this cable has been good.
- Q: Rick Hartlein, Neetrac – How could one
recognize butyl rubber as distinct from black EPR? A: At temperature
>85oC, butyl rubber will revert back to its thermoplastic nature and will
easily separate out from the conductor whereas EPR will not
- Q: H. Sarma, Kriya Consulting – Any information
known on the type of carbon black used in these compounds, high or low
structure or thermal or UV grade etc? A: Reinforcement SRF grades were
predominantly used in these early compounds
- Q: Larry Salberg, KSC – Have the other
manufacturers of black EPR also used the same criteria for the color
change? Also whether all the details of the presentation will be included
in the minutes and in which format? A: The presentation in its entirety
will be included in the minutes. This will also detail properties and
typical formulations used (see the minutes for Word document). The
advantage of the light beige color is to provide a good contrast between
the insulation and the black insulation shield. The other suppliers moved
over to the other distinct colour such as pink. There was yet another IPCA
requirement on wet electrical aging in 90oC water that forced the change
from black to other colours.
- Larry Kelly, Kelly Cables added an increasingly
greater demand for 69 kV cables with 650mil wall insulation and
requirements such as flexibility, improved loss index (dielectric constant
x dissipation factor) and strippability providing evidence that there is
residual conducting residue on the insulation necessitated the change in
colour of the EPR insulation
(see a detailed tabulation of Test requirements, typical formulations and
electrical stability of EPR cables in the technical write-up)
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EPR Mechanical and Thermal Properties (549
KB PDF)
Steven Boggs,
Electrical Insulation
Research Center Institute of Materials Science, University of Connecticut
Abstract: The mechanical and thermal characteristics of several EPR compounds
will be discussed based on new experimental data for several EPR compounds.
The thermal conductivity, thermal expansion, heat capacity and mechanical
properties of these compounds were measured as a function of temperature using
modern equipment and the data presented.
- Q: Larry Salberg, KSC – The outliers (or the
compound with properties distinct from the rest of the group) in thermal
conductivity (EPR1) and low temperature elasticity (EPR4) seem to be
different. Is this correct and if so any explanation?
A: Yes the data is correct. Of the 4 compounds studies, EPR1 was with the
higher filler content and hence the conductivity higher whereas EPR4 is of
the lowest and hence LT elasticity is the greatest. So essentially the
measurements reflect the filler content
- Q: Rick Hartlein, Neetrac – How the thermal
needles are inseted into the slabs for conductivity measurements and
whether the results will be dependent of sample origin, cable Vs molded
slabs?
A: The test samples are molded cylinders containing the needle; thermally
conducting filling compounds are used to improve the interface contact
between the measurement needle and the sample. The measurements are not
orientation dependent and hence will not be affected by their origin as to
cable Vs slab
- Q: Haridoss, Kriya Consulting – How does the EPR
designations in your presentation correspond to ICEA Type I, II, III, IV?
A: They 1,2,3, 4 designations are the same for all graphic
representations.
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Accelerated Wet Testing of Medium Voltage
EPR-insulated Cables (926 KB PDF)
Edward E. Walcott, William S. Temple, General Cable
Corporation, Suffern, NY and John T. Smith, III, General Cable
Corporation, Scottsville, Texas
Abstract: A brief history and overview of North American accelerated wet-aging
test procedures is presented. A review of accelerated wet-aging
time-to-failure and fixed time aging tests (followed by electrical test
diagnostics) for medium voltage EPR insulated power cables is presented. A
discussion of the relevance of these tests to actual field service performance
is also discussed.
- Q: Larry Kelly, Kelly Cables – Are the 2 EPR
cables used for the comparison of ACLT performance extruded with the same
conductor shield?
A: Two EPR cables with two different conductor shield, together a set of 3
test cables are used for this comparative study to demonstrate the effect
of insulation and conductor shield on ACLT performance
- Q: Larry Salberg, KSC – do the data indicate
higher the use temperature longer the life of the EPR cable?
A: Yes they do; but a lower temperature and higher stress ACLT will be a
better discriminating test
- Larry Kelly, Kelly Cables emphasized high
temperature operation of EPR cables is the norm and the higher reliability
of EPR cables has been substantiated by the field experience. Steve Boggs,
Univ. Connecticut commented that preconditioning the test cables for
equivalent moisture conditions is necessary to compare their performance
at high and low temperatures and the time to reach equilibrium moisture
content will affect the cable failures at high and low temperatures. John
Smith, General Cable acknowledged Steve’s comment and added that it is the
combination of high stress and low temperature is more useful for
comparative evaluations.
- Q: Steve Graham, Duke Power – asked about the
differences in the test water between AWTT and ACLT
A: Mark Walton, General Cable - AWTT is with tap water as specified
by AEIC and ACLT is with deionized water
- John Cancelosi, The Okonite Cables, commented
that the charts on ACLT for cables with different insulation and conductor
shields should probably include comments about the origin of the compounds
as to commercial or experimental. Upon further consideration, since this
is an educational program the authors feel that identifying the compounds,
even to the extent of "commercial or non commercial", is not appropriate
and really does not effect what is being said with regard to the points
discovered about wet accelerated aging of EPR cables
- Q: Ajit Hiranandani, DTE – Will one be able to
predict the life expectancy of the cables in service using ACLT?
A: No
- Haridoss Sarma, Kriya Consulting added
that it is always a challenge to evaluate what we can learn from these
test results and to use the results to the benefit of life time
presicability
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In Service Performance of EPR Cables
Installed in the Memphis Light Gas And Water (MLGW) Electrical Distribution
System (128 PPT)
P.Cox, MLGW
Abstract: This presentation will provide a brief background relating to the
decision to install EPR insulated cables rather than HMWPE and XLPE cables, 25
year performance history, and field aging studies performed at MLGW.
- Q: Ed Walcott, General Cable – what is the cable
design, jacketed or unjacketed
A: All unjacketed design
- Mark Walton, General Cable commented the 350-400
v.mil residual voltages after field aging correspond closely to the values
obtained in EPRI projects dealing with laboratory aging
- Q: Larry Salberg, KSC – the failure rate of 0.16
per 100 conductor miles correspond to what installed length in total?
A: Do not know exactly but certainly lots of it as this was a big project
for Memphis Light Gas & Water
- Jim Fitzgerald, The Okonite Company commented
that all these URD cables are usually operated not necessarily at high
temperatures and still performing reliably contrary to the prediction from
the laboratory ACLT at ambient temperature
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| Performance Evaluation of EPR
Underground Distribution Cables
Carlos Katz, Cable Technology Laboratories, Inc.
Abstract. - Because of the increased usage of EPR insulated cables and the
limited data available, starting in 1994, EPRI, ESEERCO and Orange & Rockland
Utilities (O&R) funded a project to develop information to quantify the aging
of various EPR cables. Five types of EPR cables, manufactured by different
companies, were aged for 7 years at three locations: namely, in CTL
laboratories under 2.5V0, in the field at O&R at 1 and 2.5 V0. The field sides
were part of actual utility circuits. Laboratory load conditions were adjusted
to mimic field conditions. Cables were periodically tested for a number of
properties. Test results indicate that there is no major difference in the
overall performance of the five EPR insulated cables. However, differences in
the characteristics of the components may lead to conditions, which can result
in premature failure, as it occurred on a number of occasions while aging one
of the cables in the laboratory. Other circumstances lead to the field
development of partial discharges in another cable.
- Q: Serge Pelissou, IREQ – How can the stability
on ACBD test be explained?
A: From the range of values
- Q: Ben Lenz, Imcorp – How are the test cables
chosen? Are these jacketed or unjacketed? Having a jacket, would it reduce
pitting that was observed after aging?
A: Test cables were unjacketed. Having a jacket would probably resuce
pitting; but if the neutral wires are loose with moisture migrating from
outside, pitting is still a possibility
- Steve Boggs, Uconn, commented that the
specification range of volume resistivity of the insulation shield is not
necessarily adequate.
- Q: John Smith III, General Cable – Do the VT Vs
Life characteristic curves predict differently for different EPR?
A: Yes; but in general to 50 years life time. The data is not included in
this presentation.
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EPR Use at High Voltages – Cost Justification
(300 KB PDF)
Rachel Mosier, Northeast Utilities
Abstract: Northeast Utilities (NU) has been installing 115-kV ethylene
propylene rubber-insulated (EPR) cables since 1999. We use these cables in our
substations where we do not have room for overhead lines. Our service
reliability is excellent, having never suffered a failure for any reason on
these lines. However, the losses in an EPR cable are relatively high compared
to other types of insulation. This presentation will detail how NU
cost-justifies an EPR cable by calculating the point at which the cost of
losses per foot of the EPR cable exceeds the cost per foot savings of the EPR
cable over other types of insulation.
- Q: Rick Hartlein, Neetrac – Lead sheathed
designs are used for economic comparisons. Has any attempt been made to
compare the economics of EPR design to metallised laminate structures with
alternate insulation?
A: No; however it is not expected to change very much with a net result of
favoring EPR design. If vault can be eliminated, they may be more
comparable.
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Transmission Class EPR Power Cables (2.9
MB PDF)
Robert E Fleming, The Kerite Company
Abstract: This segment of the EPR Power Cables Session will focus on
Transmission Class Cables. It includes a brief history of early Underground
Transmission Projects, increase in installed cable and Current Type Projects.
Also included is information on Underground verses overhead and EPR verses
Alternate Designs and Materials. The advantages and disadvantages of EPR
cables as far as electrical, mechanical, installation, maintenance and testing
of the new cable installation will also be presented.
- Q: Randy, Southwire Co – what type of sheath was
used?
A: Bonded
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AEIC Guide for Reduced Diameter Cable (49
KB PDF)
Michael L. Walker, Reliant Energy
Abstract: This presentation will provide an overview of The Association of
Edison Illuminating Companies’ (AEIC) guide for reduced diameter cables. Many
cities in the United States and countries around the world have and aging
underground cable system. This guide was developed to provide an alternative
to complete duct bank replacement.
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| Spring 2005 - Secondary Cable
Technology - A Review of Secondary Underground Cable Basics
Abstract: The topic of 600 volt underground secondary cable is
seldom discussed at ICC meetings where medium and high voltage underground
cables receive most attention. However, underground secondary cables form an
important part of a utility system considering larger utilities install more
than 1 million ft. of underground secondary cable per year and spend several
million dollars annually on secondary underground cable repair costs. This
Educational Program will focus on the topic of underground residential and
commercial services and underground streetlight cables. Presentations from the
cable manufacturers will cover the manufacture, design, materials and industry
specifications covering secondary cables. Learn about the latest secondary
cable design technologies and their potential benefits. Presentations from the
utilities will focus on their experience with underground secondary cables and
splices. The Educational Program will also feature a presentation on the
results of a utility survey on secondary cables conducted specifically for the
benefit of utilities attending this session. All files
are available in the PDF format |
For additional details on the presentations please refer to
the abstracts listed below:
- The Manufacture of 600 Volt Underground Secondary
Cables
Nick Ware, Southwire.
Abstract: Manufacturing techniques for 600V utility cables have changed in
the past several years. These products demand the highest quality and
reliability yet are viewed as commodity products in our industry. The result
is a constant pressure for improved techniques and efficiencies in
manufacturing. The various techniques of manufacture and design will be
discussed, as well as some newer product designs that can further improve
reliability.
- History of Ruggedized URD Cable Development
Kyle Cope, Pirelli Cables & Systems NA
Abstract: From its beginnings as a pair of copper conductors wrapped in
rubber to the current use of polyethylene, the idea of URD cable has been
with us since the 1800s. Polyethylene insulated secondary URD cable has been
around since the 1960s and has seen some design and process (manufacturing)
changes over the years. Current technology, the concept of "ruggedizing"
cable, has greatly improved the performance over basic polyethylene
insulated secondary URD, but has been in use since the mid 1970s. The next
advancement in the development of this design is here - Secondary URD cable
that will actually heal itself if damaged.
- Industry Standards for
600 volt Underground Secondary Cable
Bruce F. Vaughn, Alcan Cable
Abstract: Cable manufacturers utilize industry standards, and utility
customer specifications for the manufacture of 600 volt underground cables.
These industry standards are developed by cable manufacturers or user
groups, and/or certification organizations and include cable material and
test requirements. The Insulated Cable Engineers Association standards
S-105-692, “Standard for 600 volt Single Layer Thermoset Insulated
Utility Underground Distribution Cables”, and S-81-570, “Standard for
600 Volt rayed Cables of Ruggedized Design For Direct Burial Installations
as Single Conductors Or Assemblies Of Single Conductors”, and
Underwriter’s Laboratories Standard 854 for Service Entrance Cables will be
reviewed. Material, testing, and qualification requirements will be included
- Overview of Polyethylene Used for 600 volt
Underground Secondary Cable
Paul Caronia, Dow Chemical Company.
Abstract This presentation will be an overview of the polyethylene materials
used in 600 volt underground secondary cable. We will provide a review of
the types of polyethylene used, the key material parameters and the
advantages/disadvantages of the different grades of polyethylene used in
today’s 600 volt cables. Additionally, we will discuss the peroxide and
moisture crosslinking processes used to produce these cables, and why each
is used, along with an overview of the new developments in moisture cure
technology.
- Failure Rate of Bare Concentric Neutral 600-Volt
Cable
Neal Parker, Puget Sound Energy
Abstract: In the mid-1960s Puget Power installed a 600-volt cable that was
made of two insulated phase conductors and a bare tinned-copper concentric
neutral. The construction was called “flat twin” or “ribbon” cable. Neal
Parker will present the results of his investigation into this cable’s
performance. The almost total lack of reliable data resulted in unique
investigative techniques to estimate the number of these cables and how many
fail each year. From this information and anecdotal evidence, the failure
rate was estimated and a corporate approach is recommended.
- How Reliable are Your Underground Secondary
Circuits?
Timothy J. McLaughlin, Public Service Electric & Gas (PSE&G).
Abstract: There has been much interest of late in the growing problem of
secondary connection failures. Fortunately, there are a few solutions to
this nagging industry problem. PSE&G methodically tracks its underground
primary failures. We know when they failed, why they failed and how our
customers were affected. With secondary failures we are far less diligent.
The reason for this at PSE&G as well as other utilities is that secondary
failures are viewed as a small problem. They have almost no impact on your
reliability numbers as only one customer is usually out at a time. They are
low-cost when compared to primary failures, and they are usually easy to
repair. The problem comes in when you add all of these failure totals up and
see how they impact the bottom line. This presentation will focus on the
sources of these failures and the way PSE&G has attempted to fix them.
- Secondary Cable Failure Statistics at TXU Electric
Delivery Company
Richie Harp, TXU Electric Delivery
Abstract: The TXU Electric Delivery underground system consists of about
19,000 miles of cable. This is divided into 13,000 miles of medium voltage
cable and almost 6,000 miles of low voltage secondary cable. Most of the
attention for cable failures is on the medium voltage cable, but there are a
significant number of secondary cable failures that can be almost as costly
as the medium voltage cable failures. This presentation will address the
secondary cable system, the failures experienced on this system and the cost
of these failures.
- The History of Secondary Cable Designs at
Commonwealth Edison Company
John Hans, Commonwealth Edison Company
Abstract: Commonwealth Edison has approximately 27,000 conductor miles of
600-volt class cables on the system. Ruggedized cables have been used for
residential applications for the last 25 years. The presentation will review
the historical usage of 600-volt cables and their respective performances.
- ICC Educational Program Secondary Underground Cable
Survey
Steve Szaniszlo, Power Cable Consultant
Abstract: The results of a survey conducted specifically for this ICC
Educational Program on 600 volt underground secondary cables used for
residential and commercial services and underground streetlight cables will
be reviewed. This survey explores 600 volt underground secondary cable
usage, designs and splices used, cable failure rates and solutions evaluated
to mitigate cable failures by the contributing utilities. This survey was
conducted on a strictly volunteer basis for the Insulated Cable Committee,
Educational Program for the benefit of attending members and
guests.
Fall 2004 - Statistical Analysis of UD Cable Failures:
November 3, 2004. 1:00 – 5:00 p.m.
The chair presented Serge
Pélissou, Hydro Québec (IREQ) with an ICC Certificate of
Appreciation for his excellent contribution in coordinating a very
successful IREQ Laboratory Tour for the spring 2004 Educational program.
Signed attendance for the Fall 2004
Educational Program was 105.
Learn how electric utilities use statistical analysis of extruded
medium voltage underground distribution cable failures to differentiate
performance of various cable designs (HMWPE vs. XLPE vs. TR-XLPE, jacketed vs.
unjacketed), to develop circuit reliability estimates and to make proactive
cable replacement decisions. The fall 2004 Educational Program will focus on
the statistical analysis of UD cable failures with presentations from cable
manufacturers, suppliers, test laboratories and with a special emphasis on
presentations from the electric utilities. Some presentations will review
basic statistical theory relevant to analysis of cable failure data but the
emphasis is on analysis of actual utility cable failure data.
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Basic Statistical Analysis for the Utility Cable Industry
Nigel Hampton,
Borealis AB, Stenungsund, Sweden.
Abstract: A dictionary often defines statistical analysis as a process
where data from a small sample is used to derive information on the whole
population. Once this information is in our hands it allows us to make
predictions about the real world. However before we embark on a new journey into
the real world we need to understand a few things:
- the theoretical world is different from
the real world
- how good are our estimates
- how good are our data
- what can we predict and what can't we
predict
These and many other topics will be dealt with in much more
detail by other contributors. In this portion I will introduce some of the many
areas where statistics impact on the Wire and Cable Industry. The areas include
- Where do statistics and their
consequences turn up
- Data collection / conditioning – the
starting point
- Statistical distributions
- Weibull analysis – perhaps the most
useful distribution for Wire and Cable
- The important influence of the number of
samples; bias and accuracy
- The relationship of scale and scatter on
real world estimates
- The impact of size / length
- How does what we measure (pass / fail,
step vs ramp, numbers vs concentrations) effect our “predictions"
These slides are available in a
373 kB PDF
file.
- Time-Efficient Accelerated Cable Life Testing (ACLT)
- Reduce the Time and Still Get Reliable Data
J. T. Smith, III, General
Cable Corporation.
Abstract: Evaluation of insulation and semiconductive shielding
materials for MV cables and cable designs on full size cables, is routinely
carried out at several laboratories in North America (and internationally) using
a protocol known as the Accelerated Cable Life Test (ACLT). The ACLT has been
used in the MV cable industry for the last approximately 23 years, as originally
reported by R. Lyle in 1981 in an IEEE paper, and as formalized in IEEE Guide
P1407. ACLT in water-filled tanks is typically done at applied voltages that are
1.5-4X the cable's phase-to-ground rated voltage, in an effort to obtain
reliable failure data in the shortest possible calendar time. Calendar times
required to obtain failures of the entire small sample sets (n=12) of
tree-retardant crosslinked polyethylene (TRXLPE) cable can be 2 - 4X (0.75 - 2
years) the calendar time required for non-TR crosslinked polyethylene (XLPE)
data sets (4 - 6 months), while using the same conventional conductor
shield material (furnace carbon black, with relatively high sulfur and ionic
content). Cables of XLPE and TRXLPE under ACLT with conductor shields having
much lower ionic and sulfur content and improved surface smoothness (called
high performance conductor shields), can require calendar times that are 1.5
- 2X (1 - 4 years) those of conventional shields to complete. There are
statistically valid accelerated life test designs, protocols and techniques
available that can be applied to ACLT to significantly shorten these test times.
This presentation will demonstrate the use of these techniques, illustrating how
40 - 50% reductions in calendar test times can be achieved, while maintaining
the ability to differentiate between new materials or new cable designs. These
techniques (Sudden Death Testing, Test Truncation and smaller sample sets) will
significantly shorten the calendar test times necessary to obtain reliable
comparative life estimate data upon which to make commercial decisions about new
materials or new cable designs.
These slides are available in a
488 kB PDF
file.
- Bogdan Fryszczyn, Cable Technology
Laboratories asked why the contour plots have many more points than the
Weibull plots from which they are generated. John responded
contour plots are from the Monte Carlo simulation based on Weibull
distribution of the experimental data.
- Haridoss Sarma, Kriya Consulting stated the
test samples remaining after the first failure from the sudden death
populations could be used for other diagnostic tests such as ac
breakdown to characterize aging. John agreed and stated other
diagnostic tests could be carried out in parallel to life-time analysis
to get reliable data from these efficient and shortened time test
protocols thus adding value to these test designs.
- CenterPoint Energy’s URD Medium Voltage Failure
Rate History and Current Reliability Trend
Michael L. Walker, CenterPoint Energy.
Abstract: This presentation will provide failure data for the URD
medium voltage cable that has been installed on CenterPoint Energy’s system
since 1968. The data will show differences in performance as the type of
cable construction was changed through the years as well as differences in
performance related to operating voltage. Possible reasons for the
differences in operating performance will be reviewed and corrective actions
taken as a result of the increasing failure rate that CNP experienced during
the 1970’s will be presented. In summary, a review of operational practices
that have been put in place to maintain the current high level of
reliability for medium voltage cable will be presented.
These slides are available in a
103 kB PDF
file.
- Jacques Cote, Hydro Québec asked if the
failure-rates reported pertained to cable only and if they did, what are
the failure rates for the accessories? Mike replied the failure
rates represent data for cables only. Failure rates for accessories is
between 2.0 to 4.0 depending on the accessories.
- Tim Stankiewicz, Progress Energy, asked about
the number of customers at CenterPoint, the number of UG customers and
the SAIDI for UG? Mike said CenterPoint Energy has approximately
4 million customers with 35% served underground. He could not recall
SAIDI for their URD system from memory.
- Dennis Wedam, PacifiCorp asked if there was
any gain in life for cables pulled in a conduit. Mike responded
lightning effects are the same on cable whether direct buried or in
conduit and they observed no noticeable differences in service life
related directly to pulling cable in conduit.
- Bogdan Fryszczyn, Cable Technology
Laboratories asked what is TRHMWPE insulation. Mike stated
TRHMWPE is Tree Retardant High Molecular Weight PE, offered in 1981-86
and is no longer offered in the marketplace.
- San Diego Gas & Electric Underground Cable Failure
Data Base and Failure Rates
Jon C. Erickson,
San Diego Gas & Electric.
Abstract: The presentation will discuss the cable failure database
developed at SDG&E to document failures of extruded dielectric cables that
began in 1963. The method used to collect the data will be discussed. The
use of the cable failure data to develop cable failure rates will be
discussed and examples of actual cable failure rates will be presented. Use
of cable failure rates for electric circuit reliability analysis will be
discussed. The use of cable failure rates to make proactive cable
replacement decisions will be discussed.
These slides are available in a
541 kB PDF
file.
- Tim Stankiewicz, Progress Energy asked about
the confidence of forecasting. Jon replied 90% and data is
entered every year that changes the forecast.
- Vern Buchholz, Powertech Labs asked Jon about
his ideas as to why the XLPE insulated cable installed in beginning of
1981 had a much higher failure rate than the earlier manufactured HMWPE?
Jon replied the differences did not seem to be related to the
manufacturers. The most likely difference was that HMWPE was a thicker
insulation (220 mil compared to 175 mil for the XLPE cables).
- Oklahoma Gas & Electric Underground Cable Failure
Data Base and Failure Rates
Dale T Metzinger,
Oklahoma Gas & Electric Co.
Abstract: The presentation will discuss the cable failure database
and criteria for replacement developed at OG&E to document failures of
extruded dielectric cables that began in 1992. A new method developed in
2000 to collect the data will be discussed. This system is a decision tool
for crews. Failure rates will be discussed and examples of actual cable
failure rates will be presented. Use of cable failure rates for electric
circuit reliability analysis will be discussed.
These slides are available in a
446 kB PDF
file.
- Vitaliy Yaroslavskiy, Cable Technology
Laboratories asked how the seasonal peaks in failure rate can be
explained. Was the circuit heavily loaded or was it due to thunderstorm
activity or something else? Dale replied the circuits were not
heavily loaded. The real reason for the seasonal peaks was not analyzed
- Don Yau, Enmax Power Corp asked if the cable
replacement cost was capitalized and if there were plans to replace
cables in a subdivision that has cable failures exceeding the targeted
acceptable failure rates? Dale replied the cable replacement
costs are capitalized and they currently do not have targets but may be
forced to look at SAIDI, SAIFI numbers for better assessment.
- Ewell Robeson, Progress Energy asked about
analysis of cable failure repeats and if they are related to the
potential used with the thumper. Dale replied they usually try to
keep the energy low in thumping and the second failure normally occurs 1
year later. Dale suspects some damage with thumping which may cause a
future failure.
- Tim Stankiewicz, Progress Energy asked if
reporting of the failure data was in real time. Dale answered no;
usually the data is turned in by the end of the day. The crews are not
equipped with laptops.
- Wisconsin Public Service Corporation’s URD Medium
Voltage Cable Failure Rates and Why Failure Rates are Low
Greg Stano, Wisconsin Public Service
Abstract: The failure data for Wisconsin Public Service Corporation's
URD Medium Voltage Cables installed since 1965 will be given. The overall
failure rates have remained relatively low. Reasons for the low failure
rates, including lab testing of incoming cable, will be reviewed. The
results of working to maintain a reliable underground system have
resulted in improvements to the cable manufacturing processes and to the
cable industry in general.
These slides are available in a
300 kB PDF
file.
- Dale Metzinger, Oklahoma Gas & Electric asked if
present cable was purchased with a jacket and asked about (neutral)
corrosion problems. Greg replied most cables purchased are not
jacketed. Operating areas with neutral corrosion concerns is very limited
in the Wisconsin Public Service Corp. service territory. For the limited
areas where neutral corrosion occurs, when cables will be pulled into a
duct system, or soil contamination may affect the insulation semi-con,
jacketed cable is used.
- Neal Parker, Puget Sound Energy asked how a bad
segment of cable is identified. Greg replied that when a cable
failure occurs, the operating personnel use either fault indicators or a
special hi-pot tool designed to identify failed cable sections.
- Ted Nishioka, Arizona Public Service, asked if
anything special is done with the backfill going over the unjacketed cable
and if the manufacturers' cable inspection program was catching problem
samples. Greg said the installation crews are required to hand pad
the backfill used on the cable to avoid damage. Yes, the manufacturers'
inspection program does find cable problems. However, there have been
manufacturing problems not found by the manufacturers' inspection program,
but found by Wisconsin Public Service Corporation's incoming cable
inspection program.
- Cable Failure Statistics and Analysis at TXU
Electric Delivery Company
Richie Harp, TXU Electric Delivery Company,
and John T. Smith III, General Cable Company
Abstract: The TXU Electric Delivery Company underground system consists
of about 13,000 cable-miles of underground cable. Most of this cable is PILC,
HMWPE, XLPE, and TRXLPE cable. Through mergers and consolidations over the
past years, there have been several systems and databases used to monitor
and track cable assets and failures of these cables. It becomes very
difficult to locate and then to work with several somewhat massive tables at
one time, but once these tables are linked properly, a fairly significant
amount of analysis can be performed on this data. In more recent years,
realizing the potential benefits, an effort has been made to systematically
merge these systems together to be more usable by more people within the
Company. This presentation briefly describes the data systems in place now
and presents some of the analysis of this data that has been done. Using
Weibull statistics, comparisons are made of failures of cables with HMWPE
vs. XLPE vs. TRXLPE insulations. The comparisons are made by conductor size
and considering whether the cables are jacketed or not. Life predictions are
made for each category based on these statistics.
These slides are available in a
373 kB PDF
file.
- John Ainscough, Xcel Energy asked roughly how
much of the originally installed HMWPE has been replaced and how are the
cable replacements properly handled in Crow-AMSAA modeling. Richie
replied the HMWPE is direct buried and replacement has been limited;
around 2/3 of the original installed cable is still in service. The crow-AMSAA
analysis works with a repairable system; no special adjustments are
necessary.
- John Hinkle, PPL Elect Utilities asked if the
data was presented to Management. What do they think? And what do they
plan to do? Richie replied the data has not been presented yet.
- Serge Pélissou, Hydro Québec asked if the XLPE/HMWPE
cables were direct buried? He also asked if you consider the failure of
the HMWPE cables prior to 1990 (the start date of your database) would the
failure analysis change and how. Richie replied the cables are
direct buried; yes probably the failure analysis may change if the failure
occurrences prior to 1990 are taken into account.
- Bill Temple, General Cable asked if one can
assume the Crow-AMSAA model cusp is probably due to the stoppage of the
installation of HMWPE cables and the start of XLPE cables. He also asked
if the vintage of the each cable installed was available and if this was
the case, was there an opportunity to analyze data based on installed
service. Richie replied it was possible. The vintage data is
available and TXU has started some analysis based on that.
- Neal Parker, Puget Sound Energy commented the
failure data indicated that HMWPE had a lower failure rate than XLPE. Neal
suggested that today it may have a lower failure rate because the
locations in the HMWPE that had significant defects have failed and been
purged from the system, so the remaining cable may have a lower failure
rate than XLPE. Basically, HMWPE has had a multi-year head start at this
purging process. This does not mean that during its entire life span HMWPE
is a more reliable cable. Richie agreed with the comment and stated
the same concept holds for XLPE, except that as stated, the HMWPE has a
head start on the XLPE. But both insulation types on the TXU system are
relatively old so they both should be approaching their 'purged' failure
rate. TXU began installing HMWPE in the mid 60s and XLPE in the early 70s.
In other words, the oldest HMWPE cable is about 35-40 years old and XLPE
is about 30-35 years old."
- Analysis of Cable Reliability and Lifetime Expectancy
Dr. Miroslav
Begovic with an introduction by Rick Hartlein, NEETRAC (Georgia
Tech).
Abstract: The area of diagnostics and expected lifetime in cables has
recently become one of the focal points of research interest at NEETRAC
(Georgia Tech). The presentation will focus on prognostics with emphasis on
the estimation of remaining life and failure rates in cables and the
interrelationships between accuracy, precision and confidence. Two aspects
of our work are included in the presentation:
- A method is demonstrated that
measures the accuracy and uncertainty of remaining life estimates using
experimental data from accelerated aging tests. This method reduces the
uncertainty of the forecast and ill-conditioning of the problem (caused by
widely varying experimental lifetimes and their proportion to much longer
lifetime estimate at normal operating conditions) by incorporating an
approximate analytical model of the cable lifetime (governed by the
physics of component failure.) Results from the example indicate that the
estimates of the cable lifetimes are possible to be extracted (and their
confidence ranges assessed) from such data. Moreover, using the
methodology of probabilistic simulation, it is possible to assess the
relative merits of various accelerating aging tests with respect to the
end result (lifetime estimate) and predict the impact of not using some of
them.
- Based on the earlier work (W. Forrest) on estimation of
the cumulative failure rates in homogeneous populations of cable of
various ages, we propose a method for identification of the statistical
parameters of failure rates based on a more general, nonlinear model.
Moreover, we use that information for forecasting failure rates into a
finite horizon in the future, and assess the need for replacement based on
the desired failure rate scenario. By performing probabilistic (Monte
Carlo) simulations, we propose to associate the forecasts of the necessary
investment with the desired confidence of the final outcome (desired
failure rates). Such approach has a very good application potential in
development of asset management strategies for a variety of classes of
aging equipment.
These slides are available in a
328 kB PDF
file.
-
Ray Awad, Trans Energie (Hydro Québec) asked: what is the
size of the cable population you are looking at; you replace 300 miles/year.
Miroslav replied the size is 350,000 total miles; so we are replacing 10% of
the cables.
-
Nigel Hampton, Borealis asked considering the 29 year estimated
life, what was the probability used and what was the length of cable. Miroslav replied the probability was 63% using raw data from the EPRI study.
The estimates are for the lengths used in the EPRI study which I believe was
30 ft.
-
Mark Walton, General Cable commented it was not obvious from the
presentation that the life estimate of 29 years for 30 ft sample @ 63.2
B-life is based on wet accelerated aging conditions. Miroslav responded the
data used was given by Rick Hartlein and Mark was probably correct.
-
Additional references on statistics was provided by
Haridoss Sarma, Kriya Consulting and can be found in Appendix E9.
Fall 2003
- High Voltage Cables
- HV XLPE Cables - Reviewing the
State of the Art; Design and Aging Issues
Nigel Hampton,
Borealis AB, Stenungsund, Sweden.
Abstract: The introduction of crosslinking processes
has permitted the continuous operating temperature of polymeric cables (XLPE &
EPR) to be increased to 90oC, equaling that of oil filled (LPOF &
HPOF) paper and polypropylene paper laminate (PPLP) cables. The use of XLPE as
the insulation for transmission cables has grown steadily since the early
1990’s. Today XLPE is the insulation system that is preferred to the
traditionally lapped insulation (paper or paper polypropylene laminate) oil
filled cables. The preference for XLPE cables has been due to the low
dielectric losses, simplicity of operation and the low environmental impacts
that can be achieved. However reductions in the size of cables significantly
assist the dissipation of heat, give longer dispatch lengths, reduce overall
system costs and improve the attractiveness of XLPE solutions. The
presentation will
-
Examine the status of installed systems
-
Discuss the importance of ageing in determining the design
-
Discuss some of the features that can influence the
electrical performance (short term and ageing) of XLPE HV cables
-
Present some issues that need to be considered in the future
These slides are available in a
711 kB PDF
file.
- Ampacity and Sheath Bonding
John Cooper, Power Delivery Consultants, Inc.
Abstract: Ampacities of
extruded-dielectric cables are typically higher than those for paper-insulated
pipe-type or self-contained fluid-filled cables of the same conductor size
because of lower dielectric losses, and absence of losses caused by magnetic
effects of pipe-type cables. In addition, system considerations – charging
current, MVAR compensation, and load sharing – are superior to those for
paper-insulated systems. Duct installations – typically required in city
streets in the U.S.and commonly used overseas as well - cause ampacity
reductions of 10-15 percent versus direct-buried installations.
Extruded-dielectric cables are not amenable to hot-spot reductions the way
that high-pressure liquid-filled cables are, so avoiding – or at least
monitoring – potential hot spots is of great importance. Sheath bonding
methods – solid bonding, cross-bonding, multiple single-point bonding – have
large effects on cable ampacity and cable system operation.
This presentation will include the following topics:
- Brief discussion of ampacity principles
for extruded-dielectric cable systems
- Listing of major parameters that affect
cable ampacity, both steady-state and emergency
- Graphs and tables of effects of these
major parameters on ampacities
- Options for sheath bonding
- Effects of these options on ampacity,
sheath voltages, equipment requirements, and effects on parallel conductors
These slides are available in a
303 kB PowerPoint file
or as a 179 kB PDF
file.
- HV Accessories, Design, Testing and Installation
Recommendations
Henk Geene, Pirelli Cables and Systems N.V.
Abstract: Since the introduction of HV extruded
cable systems, more than 25 Years ago, the related cable accessories underwent
significant changes. The first generation of accessories was characterized by
man-made installation techniques, like taping for joints and the use of
insulation oils in terminations. The newest generation accessories are fully
prefab and pre-tested, with limited use of insulating oil and gasses.
The presentation will address the following topics:
- Different accessory designs and
installation characteristics
- Testing of accessories
- Installation recommendations for
accessories
These slides are available in a
5860 kB PowerPoint file
or as a 4207 kB PDF
file.
- HV XLPE Cable Manufacture and Design
Axel Schlumberger, Forte Power Systems
Abstract: High Voltage (HV)
XLPE insulated cables require state of the art design, materials and
manufacturing processes. We will discuss all components of HV cable, including
conductors, insulation systems, metallic screens / sheaths and outer
protection relative to industry standards, materials and manufacturing
processes in use today. Topics:
- Copper & Aluminum conductors, ASTM and
IEC standards, compressed, compact, segmental and other constructions
- XLPE insulation, conductor shield,
insulation and insulation shield compounds, review of different extrusion
processes, material handling, quality control methods and stress based
design criteria
- Use of tapes and their functions
regarding bedding, water blocking and electrical properties - Brief overview
of metallic screens and metallic sheaths, their application and selection
criteria
- Cable jacket materials and
semi-conductive outer layers for jacket integrity testing
- Cable standards and organizations
These slides are available in a
1142 kB PowerPoint file
or as a 724kB PDF
file.
- Hydro Quebec Experience with HV XLPE Insulated Cables
Ray Awad, Senior HV Cable Engineer, TrasnsEnergie (A
Division of Hydro Québec)
Abstract: Hydro Quebec has been successfully using High Voltage XLPE
insulated cables in its vast 120 kV underground network since 1989. All new
installations in major cities, substations as well as power generating
stations use these polymeric cables. Some 70 new circuits (including some 56
in the Beauharnois power station) have been added to the network. These cables
have been also used at 230 kV level and more are planned for 315 kV. A new
generation of optimized design has been introduced in 2000. The cost of new
underground transmission lines has been decreased by some 27%. Maintenance
cost has been also reduced by 50%. Prequalification testing of XLPE cables
rated up to 400 kV have been carried out at Hydro Quebec research facilities
laboratories. Innovative techniques such as joint bays and plug in lightning
arrestors for sheath protection have been introduced.
These slides are available in a
2916 kB PowerPoint file
or as a 825 kB PDF
file.
-
Rio Salado Project Phase Two: 230kV
Solid Dielectric Cable Underground Lines Installation
Ted Nishioka,
Arizona Public Service Company
Abstract: The City of
Tempe, requested two circuits of existing 230kV overhead lines installation
be converted to underground near the Tempe Town Lake area so that they would
be able to construct their Performing Arts Building. This presentation
will discuss the engineering design and installation of an additional 6100
circuit feet each of 230kV solid dielectric cable circuits that extends from
each of our other two original 4000 circuit feet installation.
These slides are available in a
19194 kB PowerPoint file
or as a 3448 kB PDF
file. Hank Geene also contributed to this
presentation. His slides are available as a
8127 kb PowerPoint file and
as a 2710 kB PDF file.
-
Testing of HV Extruded Cable Systems, A
Necessary Step to Achieve System Reliability
Willem Boone, KEMA
Abstract: In this
presentation attention will be paid to different types of testing with a view
to the related purpose:
-
To check
if the cable is well designed
-
To check
if the cable is well produced
-
To check
if the cable system is well installed
-
To check
if the cable system behaves reliably during operation
Different methods of testing will be discussed, both from an
international perspective and according to US standards, in particular to
accomplish system reliability efficiently. Finally
future trends and related new developments will be discussed.
These slides are available in a
417 kB PowerPoint file or as a much smaller
70 kB PDF
file.
Spring 2003- An Overview of PILC Cables
- Historical Review of PILC Cables, William A. Thue,
Consultant
These slides are available in a
130 kB PowerPoint file or as a
107 kB PDF
file.
- PILC Cable Design and Manufacture, Joe Zimnoch,
Consultant.
Abstract:
- Exactly what is a PILC cable?
- Basic cable designs.
- Function and properties of each cable component.
- Cable manufacturing steps.
- Past and current AEIC industry specifications.
- Improvements over the last 100 years.
- Notable features and characteristics of PILC cables.
These slides are available in two parts: the
first is a whopping
28 MB PowerPoint file or as a much smaller
(4 MB) PDF
file; the second is a whopping
3.3 MB PowerPoint file or as a much smaller
(1.4 MB) PDF
file
- Cable Operating Experience & Practices, Stan Heyer,
PECO Energy.
Abstract: Review experience with PILC cables, what
are pro and cons, review maintenance/repair issues/practices, why are
utilities considering/moving to PILC replacement. Regarding the pros and cons
of PILC photos of various PILC splices will be shown to illustrate the wide
range of taps that can be made with PILC. This is a significant advantage of
PILC cable. These slides are available
in a monster
59 MB PowerPoint file or as a much smaller
(672 kB) PDF
file.
- Reliability Improvement of PILC Cable Circuits by CBM
Programs, Willem Boone MSc, KEMA.
Abstract: PILC is a so called "classical" type of cable, reputable but usually
relatively old. Because of high reputation, diagnostic testing of old cable
makes sense: old cable is not necessarily bad cable. Usually by replacing only
a few accessories or parts of cable the quality of the cable circuit can be
restored. If utilities want to improve reliability of PILC cable circuits,
Diagnostic Testing Induced Condition Based Maintenance has been proven to be
effective. In this presentation attention will be paid to the Condition
Based Maintenance (CBM) - strategy for PILC and in particular the available
diagnostic methods to accomplish CBM intentions. The most important method,
Partial Discharge Detection (PDD), will be dealt with in more detail.
This presentation will also consider the most essential and
probably the most difficult part of PILC PD testing: the conversion of
measured information into practical recommendations: "The interpretation".
Finally two case studies will be discussed, showing that the CBM-approach
works out successfully in the daily practice of utilities. These
slides are available in a 773 kB PowerPoint file or as a much smaller
(167 kB) PDF
file.
- Condition Assessment of PILC Cables,
Carlos Katz, Cable Technology Laboratories
Abstract: Cable Technology Laboratories (CTL) has
developed a series of tests to assess the condition of PILC cable. These tests
include power factor versus voltage stress and versus temperature, plus a high
voltage time test to failure. Using this approach, it has been feasible to
assess the relatively condition of PILC cables. This test is destructive in
nature. Using a similar technique, cables categorized in poor
condition by partial discharge diagnostics, have been tested in the
laboratory. The results do not confirm the poor condition of the field
assessed cables. Additional evaluations are performed by dissecting PILC cables and studying
the mode and pattern of cable insulation degradation and failure.
These slides are available in a
23 MB PowerPoint file or as a much smaller
(2.7 MB) PDF
file. Carlos also distributed a brief paper
entitled, Further Serviceability of 40 Year Old PILC Cable a
110 kB PDF version of this paper has been
posted.
- EPRI Project on Assessment of PILC Cable Condition from
Electrical, Chemical and Metallurgical Tests, Vern L. Buchholz,
P.Eng., Powertech Labs Inc.
Abstract: An EPRI project on condition assessment of
PILC cable was recently completed by Powertech Labs. Sixteen lengths of
field-aged PILC cable were collected from utilities across North America. Two
of these lengths were removed from an in-service PILC feeder circuit on which
diagnostic tests had been performed. Three different categories of diagnostic
tests were performed on the field-aged PILC cable samples. These included
chemical and dielectric tests on paper tape and on oil samples, electrical
diagnostic tests in the lab and on-site on full-sized field aged cable
lengths, ac breakdown and water-ingress tests on the same field aged cables,
and metallurgical tests for the evaluation of lead sheath aging. A short
presentation will describe the objectives and tests methods.
These slides are available in a
12 MB PowerPoint file or as a much smaller
(2.8 MB) PDF
file.
- Getting the Lead Out: Options for PILC Replacement,
Brent Runyon, Pirelli Power Cables & Systems.
Abstract: The long history of PILC cables may be
coming to a close. More and more utilities are seeking a viable alternative to
this cable design, due primarily to two reasons:
- difficulty in installing and maintaining this type of
cable and
- pressure from environmental groups.
This presentation will deal with the future of PILC
replacement and the pros and cons of current alternatives.
These slides are available in a
1.5 MB PowerPoint file or as a much smaller
(334 kB) PDF
file.
Fall 2002 - URD Cable Design,
Past, Present and Future
Spring 2002 - Accelerated Cable Testing and Its Correlation to Field Testing
For the spring 2002 ICC Educational Program we had the pleasure of
featuring a renown group of experts in the field of accelerated laboratory aging of medium
voltage extruded power cables. Their presentations covered various accelerated cable aging
tests used in North America and Europe. Each aging test was described, typical data will
be presented and where possible, correlation to field aging was discussed.
- Aging of Medium Voltage Extruded Dielectric Cables Under Wet
Conditions
John Densley, ArborLec
Solutions
Abstract: Extruded insulations have been used in medium voltage power cables since the
sixties. These materials have high breakdown strength and a low dielectric constant,
making them ideal insulating materials for power cables. However, cables installed in the
late sixties and early seventies began failing after only five to ten years in service.
The majority of the failures were caused by tree-like growths, referred to as water trees,
in the insulation. Extensive studies were made to determine the mechanisms of water
treeing, in the development of accelerated aging tests on cables, and to develop tree
retardant materials to suppress water trees. The presentation will briefly review the
aging mechanisms, the parameters that affect tree growth, and also the different
accelerated tree-growth and accelerated aging tests. These slides are
available in a 131 kB PowerPoint file or as a much
smaller (72 kB) PDF file.
- It’s All In The Interpretation – Outliers Count
Carl C. Landinger, PE, Dir. Of
Technology, Hendrix Wire & Cable
Abstract: Wet testing of cables in various stages of completion to compare
materials or attempt to predict relative longevity in service has been conducted since the
early 60's or longer. The direction of the temperature gradient and location of the test
water have a controlling influence on the test results. These factors determine if the
test must be limited to comparing very similar materials or if the test can also be used
to compare dissimilar materials. As a service life predictor, the most valuable data
points may be the outliers which, unfortunately, are all to commonly ignored. These
slides are available in a 80 kB PowerPoint file or
as a much smaller (38 kB) PDF file.
- AEIC Accelerated Water Treeing Test – History, Test Program,
Results, Pros and Cons
Rick Hartlein – Georgia
Tech NEETRAC
Abstract: The AWTT is part of a qualification test designed to assure that
cables meet basic performance requirements. The primary information provided is the
reduction in ac dielectric strength as the cable is aged in water up to a year under
relatively moderate accelerated test conditions. It also provides specific, minimum
performance requirements that cables have to meet in order to be considered qualified. It
is also often used as a performance comparison test. The test setup is well defined, and
the test conditions are specifically established. This presentation will provide a review
of the AWTT test procedures, typical AWTT data as well as the pros and cons of the data
generated by the AWTT. These slides are available in a 828 kB PowerPoint fileor as a much smaller (110 kB) PDF file.
- Accelerated Cable Life Testing
Mark D. Walton, Manager of
Customer Testing Services, General Cable’s Marshall Technology Center.
Abstract: A review of the various ACLT protocols being employed at General
Cable's Marshall Technology Center is presented. The difference between a time-to-failure
ACLT protocol and a retained breakdown strength ACLT protocol will be explained. ACLT test
variables and their influence on test results will be discussed. Mathematical aging model
development using ACLT test techniques will be discussed and an aging model for XLPE
cables operating in a wet environment will be presented. Finally, a relationship between
ac breakdown strength and cable life for XLPE-insulated cables will be presented. These
slides are available in a 752 kB PowerPoint file or as
a much smaller (313 kB) PDF file.
- Accelerated Cable Aging At 500HZ, Time Is Money!
Willem Boone, MSc, KEMA
Abstract: After all the negative experience collected so far with poor
performing extruded cables, it is very important to know if a new cable insulating
material will be susceptible to water treeing or not. By applying accelerated aging, in a
relative short period of time the material is being tested for how it will perform under
service conditions during cable life. However, accelerated aging under power frequency
conditions usually takes a long time of about 2 years before any decisive conclusions
about the performance of the insulating material under service conditions with respect to
water treeing can be drawn. Apart form the high testing costs; this long period of time
may cause liability problems, because usually the cable is already in service before the
accelerated aging test has been completed. Extensive testing of laboratory models as well
as cable samples demonstrated clearly that accelerated aging under 500 Hz conditions could
reduce the necessary aging time from 2 years to 3000 h, (about 4 months), without
influencing the aging mechanism as observed under power frequency conditions. In this
presentation a survey will be given of test results to prove the accelerating effect of
500 Hz testing voltage. Besides information will be given about practical testing
experience in the Netherlands, where according to the national standard this type of
testing is being used for several years successfully. These slides are
available in a 2749 kB PowerPoint file or as a much
smaller (31 kB) PDF file.
- Harmonization of Long Duration Test Method in Europe
Vic Banks, Pirelli Cables (UK),
Energy Cables Division
Abstract: HD 605 ‘Electric cables - Additional test methods’,
prepared by CENELEC TC20 for Europe, specifies the test methods for distribution and power
station cables with extruded insulation for rated voltages from 0.6/1kV up to 20.8/36kV.
As published in 1996, HD 605 included a large number of different long duration test
methods to assess the resistance to water of medium voltage extruded insulation cables.
CENELEC TC20 agreed that a study be carried out to formulate a harmonized test regime.
There were three basic test methods in HD 605, namely the so-called UNIPEDE, VDE and
Temperature Gradient regimes. An attempt was made to harmonize these three regimes but,
after due consideration, it was agreed as a first step to rationalize the variations
existing in the UNIPEDE regimes. This involved the study of a number of parameters,
including cable construction, preconditioning, water type, aging voltage/stress, aging
temperature and test duration. Tests were made at a number of establishments by cable
manufacturers, utilities and test houses throughout Europe and included comparison with
the VDE regime. The Temperature Gradient regime was left for future consideration. This
presentation outlines the test methods, the tests carried out and the results obtained to
achieve harmonization of the UNIPEDE and VDE regimes, a harmonized test method having been
submitted in 2000 for inclusion in HD 605. Tests are in progress to this regime and
results are expected to be available in 2002. Future considerations include shortening of
the test duration, taking into account not only the results of the harmonized regime but
also higher frequency aging and the temperature gradient regime. These
slides are available in a 340 kB PowerPoint file or as
a much smaller (23 kB) PDF file.
- Comparative Wet Aging Tests of Medium Voltage XLPE Cables (AEIC
AWTT & DIN VDE 0276)
Lauri Hiivala, Nexans Canada
Abstract: Together with the improvement of designs, materials and compounds,
test methods for accelerated aging under wet conditions have also been developed. One goal
has been to have a tool for discriminating between "bad" and "good"
cables. Standardized wet aging test methods for extruded medium-voltage cables such as the
North American AWTT according to AEIC Specification CS5-94 and the German VDE test
according to DIN VDE 0276 are able to differentiate between insulation systems. The
retained AC breakdown strength after aging is the most important criterion. Water tree
investigations only provide additional information. Wet design cables that perform well in
these tests should have a life expectancy of more than 50 years. These
slides are available in a 9759 kB PowerPoint file or
as a much smaller (152 kB) PDF file.
- CTL Aging of Medium Voltage Cables
Carlos Katz, Chief
Research Eng., Cable Technology Laboratories, Inc.
Abstract: Low temperature, voltage accelerated aging of medium voltage cable
has been used successfully at CTL Laboratories for over 15 years to simulate URD cable
aging in the field. This aging method is being used at present, in a number of cable
projects. In one of these projects, the laboratory aging at 2.5 times rated voltage is
being compared with aging in the field at 2.5 times rated voltage and also field aging at
operating voltage. The rate of degradation of the low temperature aged cable justifies the
use of this low cost technique, in the accelerated test aging of the cables. The
presentation will provide details of the methodology and overall results. These
slides are available in a whopping 15MB PowerPoint file
or as a much smaller (296 kB) PDF file.
- Using ACLT as a Cable Design Aging Test
Rick Hartlein – Georgia
Tech NEETRAC
Abstract: The ACLT has historically been used to evaluate the performance of
15 kV class cable cores – that is cables with a 175 mil wall, no jacket and a
conductor that is not water blocked. However, utilities commonly employ cables with a
water blocked conductor and a jacket and they often use cables with a wall thickness that
is greater than 175 mils thick. These changes to the cable structure can have a profound
influence on cable performance. For this reason, Georgia Tech NEETRAC has explored the use
of ACLT to test complete cable designs instead of cable cores. This presentation will
cover how the cable design aging test is conducted and provide results from an early
design test program. These slides are available in a 992 kB PowerPoint file or as a much smaller (97 kB) PDF file.
Fall 2001 - Basic Power Cable
Design, Part II
- Basic Electrical Characteristics Part II
Carl C. Landinger,
Hendrix Wire & Cable
Abstract: Power cables are utilized by the application of voltage and current on the
cable. The presence of voltage and current is accompanied by electrostatic and magnetic
fields. These both act upon, and are acted upon by, cable, materials, geometry and
adjacent facilities. This course gives a brief overview of the electrical characteristics
of single conductor power cables and a discussion of the impact of adjacent cables and
facilities. The student is made aware of several important characteristics in order to
take them into account when considering specific cable applications. Slides in PowerPoint format 205 kB, slides in PDF format 359 kB
- Fundamentals of Electrical Insulation Materials
Bruce S. Bernstein, Consultant
Abstract: This is the second in a series of presentations on "Fundamentals of
Electrical Insulation Materials". The previous seminar (spring, 2000) reviewed
the basics of polyolefins. This presentation will cover two topics: (1) Compare the basic
properties of paper/oil insulation with that of polyolefins; the natural polymer
(cellulose) and synthetic polymers (based on ethylene) are significantly different in
manufacture, processing and in cable aging behavior, as well as response to diagnostic
tests. (2) Fundamental electrical properties of Polyethylene including response to low and
high voltage stress. Slides in PowerPoint format 683 kB,
slides in PDF format 461 kB
Spring 2001 -
An Overview of Diagnostic Testing of Medium Voltage Power Cables (Non-PD Methodologies)
- "An Overview of Diagnostic Testing of Medium Voltage Power
Cables," John Densley,
ArborLec
Solutions Inc.
Abstract: Distribution cable systems represent a large capital investment for
electrical utilities. In today’s competitive environment, electrical utilities are
being faced with decisions to maintain, repair, refurbish, or replace their cable systems.
This requires an assessment of the condition of the cable system by understanding the
aging mechanisms and also the development of diagnostic tests. According to a 1994 report
of CIGRRE WG 21:04, the purpose of a diagnostic test is ‘to evaluate and locate
degradation phenomena that will cause cable or accessory failure’. The
presentation will describe the main aging and failure mechanisms of distribution cables
and the advantages and limitations of diagnostic tests. Diagnostic tests usually measure
or monitor one or more properties of the insulation system that are related to aging
and/or failure. Some tests measure localised properties; for example, partial discharges
at contaminants, voids or protrusions, while others measure an overall property, for
example tan delta (loss, dissipation or power factor). These topics will be discussed in
the presentation. These slides are available in a 340 kB PowerPoint
file or as a much smaller (39 kB) PDF file.
- "Assessment of Some Diagnostic Techniques for PILC Cables,"
Jean-Pierre Crine, Consultant.
Abstract: Based on a paper by: Vern Buchholz, M. Colwell and J.P. Crine, Powertech
Labs Inc., Vancouver, Canada, S. Cherukupalli, B.C. Hydro, Vancouver Canada, B. S.
Bernstein, EPRI, Washington, USA (now retired). Condition assessment of Paper Insulated
Lead Covered (PILC) cables is a crucial factor for many utilities that have considerable
lengths of these older design cables still in service. This paper is devoted to the
evaluation of various electrical and chemical tests designed to investigate failure
mechanisms such as thermal aging, water ingress and discharges. The non-destructive
electrical tests performed on field-aged PILC cables were: the isothermal relaxation
current (IRC), the LIpATEST leakage current test, the return voltage method (RVM) and the
ac breakdown strength. In addition, partial discharges were measured in the field on an
energized, in-service PILC feeder. Dielectric thermal analysis (DETA), Fourier transform
infra red (FTIR) spectroscopy and moisture content analysis were also performed on small
samples of paper tapes and oil taken in the same samples. It is shown that a combination
of these analytical techniques give a better understanding of the aging condtion of the
tested PILC cables. While studies employing IRC and RV have been reported for XLPE, little
information is available for PILC, and this effort is apparently one of the first in this
direction. The methods do show promise for providing meaningful information, but
additional work is required for a full assessment of PILC cables condition. Some practical
suggestions for future work are also made. These slides are available in a 135 kB PowerPoint file or as a 35 kB PDF file.
- "Detection of Water Trees in XLPE Distribution Cables Using the
IRC Method," Henning Oetjen, HDW Electronics, Inc.
Abstract: The IRC (Isothermal Relaxation Current) method detects the presence of
water trees and the extent of their damaging effect on XLPE cables. It allows assessing
the condition of the cable before making the decision to repair, replace or rejuvenate it.
The method is based on the measurement of the relaxation current with regard to 3 distinct
time constants, which can be used to describe the behavior of water trees with different
degrees of progression under the influence of a polarizing electrical field. The session
will provide a technical description of the method, aspects of its practical use in the
field and field data. These slides are available in a 1.4 MB PowerPoint file or as a 1.1 MB PDF file.
- "Assessment of the Aging Condition of PILC Cables Using the
Voltage Return Method", Henning Oetjen, HDW Electronics, Inc.
Abstract: The Voltage Return Method assesses the condition of PILC cables by
determining the effect of water, which is adsorbed by the insulation. The water changes
the characteristic return voltage trace, which consists of 2 components. One component
represents the change in the insulation resistance RG and the cable capacitance
CG (parallel elements); the second component is influenced by the time constant
of the polarization effect Rp1Cp1. Both components change the return
voltage curve in a characteristic way. The session will provide a technical description of
the method, aspects of its practical field use and some field data. These slides are
available in a 686 kB PowerPoint file or as a 606
kB PDF file.
- "Medium Voltage Power Cable Diagnostics by Frequency Domain
Spectroscopy," Peter Werelius, Programma Electric AB.
Abstract: Frequency Domain dielectric Spectroscopy (FDS), or measurement of
capacitance and loss in a frequency range, is a non-destructive method for material
characterization and now available for practical diagnostic measurements under field
conditions. The method shows significant advantages in the interpretation of the results
since more data allow for accurate temperature corrections, separation between different
materials and minimization of the influence of accessories such as cable terminations. Two
main application areas of the method are diagnostics of extruded medium voltage cables
suffering from water tree deterioration and determination of moisture content in PILC
cables. For diagnostics of extruded cables, the high voltage FDS is used and it is found
that depending on aging stage and type, water tree deteriorated insulation exhibits a
characteristic response, which allows for reliable assessment of the insulation condition.
For determination of the average moisture content in PILC cables, the method is used at
low voltage. Higher moisture content gives a characteristic increase of losses and the
loss minimum correlate well to moisture content. These slides are available in a 2.3 MB PowerPoint file or as a much smaller (230 kB) PDF file.
- "Tan Delta (Dissipation Factor) Measurements as an Effective
Tool in Determining the Insulation Condition of Power Cables," Craig Goodwin,
HV Diagnostics.
Abstract: The presentation will cover one of the most widely used and proven
on-site diagnostic techniques available to determine the insulation condition of power
cables. This technique provides insight into the overall condition of the cable
insulation. The Tan Delta diagnostic integrated system from BAUR utilizes a high voltage
Very Low Frequency (VLF) generator to apply both variable voltage and/or variable
frequency onto the cable under test. Measurements can be made in both the frequency and
time domain. A brief description of theory behind this diagnostic technique, the equipment
used, a comparison with other methods and practical examples from field will be presented.
These slides are available in a 1.7 MB PowerPoint
file or as a 1.5 MB PDF file.
Fall 2000 - Partial
Discharge Testing
- Fundamentals of PD and PD Detection in the Context of
Shielded Power Cable, Steve Boggs,
University of Connecticut and University of Toronto.
Abstract: Partial discharge (PD) refers to any incomplete breakdown of an
electrical system such as may be caused by discharge in a cavity, discharge between an
energized electrode and a floating component, tracking along an interface, or discharge
within an electrical tree. Traditionally, the details of partial discharge phenomena have
been or interests only to specialists in the field; however, with the advent of widespread
PD testing of distribution cable systems, utility engineers are being called upon to make
decisions based on the results of such testing which can result in million dollar
expenditures. As a result, such engineers need to understand the fundamentals of partial
discharge phenomena, and this presentation will be an introduction thereto, including how
PD signals are generated, on what their amplitude depends, effect of PD on materials, etc.
(paper in Adobe Acrobat format, slides in PowerPoint format).
- Very Low Frequency Partial Discharge Detection, an Experienced
Diagnostic Tool for Distribution Cables, Willem Boone, KEMA
Diagnostic Services. Abstract: To perform predictive maintenance programs for
distribution cables circuits effectively; diagnostic methods are needed to avoid service
failures and to reduce cost. The VLF PDD method is an experienced method to locate
potential failures, based on the detection of partial discharges in distribution cables.
The common method based on the principles of reflectrometry has recently
been extended by introducing the so-called multi terminal synchronized diagnostic method.
By using this diagnostic method, branched cable circuits and cables of long length (over
15,000 ft) can be diagnosed successfully. In this presentation after an introduction about
different maintenance philosophies, the technical principles of reflectrometry based
testing and multi terminal synchronized testing will be explained and typical results of
interpretation of the measured information and the conversion into practical
recommendations with regard to maintenance actions, like repair or exchange of components.
Finally a few cost/benefit evaluations concerning diagnostic testing services and related
actions, will be dealt with. (slides in PowerPoint
format)
- On-Site Cable Diagnostic with Complex Discharge Analyzing
(CDA) Test Voltage, Dirk Russwurm, HV Technologies Inc.
Abstract: In order to improve the reliability of an electrical grid while
reducing the cost via condition-dependent maintenance, diagnostics of the high voltage
components in the grid is essential. Therefore, also the demand for diagnosis of power
cables is increasing. For partial discharge (PD) testing of power cables, the cable has to
be energized with alternating voltages equal or above the operating voltage. As one can
imagine, the high capacitive load makes the off-line testing of power cables difficult.
Several approaches to overcome this problem exist. However they are always a trade-off,
with some disadvantages. For partial discharge testing of the cable, we therefore
developed a new, hybrid voltage shape and it’s generator. It combines the advantages
of:
- testing with power frequency, which provides PD results identical as
under operating conditions
- testing with VLF (<=0.1 Hz) with its low exciting power demand
- testing with oscillating voltages, which keeps the generator simple and
reliable
The CDA system is used for testing medium voltage PILC, XLPE and EPR
cables as well as mixed cable structures. A condition assessment of aged cables can be
performed as well as PD tests for the commissioning of new cables. The system is
commercial available since four years. Built into a test van, it is in use at several
utilities in America and Europe. The new CDA waveform with its advantages and
disadvantages will be explained to the audience, followed by a description of the standard
test procedure. Several test results will be discussed. At last, an outlook of future
developments will be given. (slides in PowerPoint
format)
- On Line Partial Discharge Detection in Transmission and Distribution
Cable Systems, Nagu N. Srinivas, Detroit Edison.
(slides in PowerPoint format)
- Partial Discharge and Tan Delta On-Site Testing, Craig
Goodwin, HV Diagnostics
Abstract: The presentation covers the use of two of the most successful and widely used
on-site diagnostic techniques, partial discharge and tan delta, to determine the
insulation condition of extruded cables. Both Partial Discharge and Tan Delta diagnostic
interfaces are used in conjunction with a Very Low Frequency High Voltage Generator as one
integrated system to allow on-site diagnostics tests to be performed with one integrated
system. A brief description of the equipment, the practical issues behind the diagnostic
techniques involved and examples from various on site tests are presented. Interesting
differences and similarities between the two diagnostic techniques and the information
that they provide is also presented. (slides in
PowerPoint97 format)
- Field Testing at Power Frequency, Matthew S. Mashikian,
Imcorp.
Abstract: Topics will include:
- Testing philosophy
- Excitation voltage
- PD location by reflectometry
- PD location by arrival time
- Application to the testing of branched circuits and to on-line testing
- Discussion of on-line versus off-line testing
These slides are available in PowerPoint
(7 MB) and as a much smaller PDF (515 kB)
- Partial Discharge On-site Diagnosis of Distribution Power Cables at
Oscillating Voltages, Edward Gulski, Delft University of Technology.
Abstract: It is known that more than 50% of failure in medium voltage power cable
networks in related to insulation problems. These problems may have two different origins
and they are mainly due to:
- poor workmanship in accessories of new or repaired cable sections,
- defect induced insulation degradation of cables and accessories.
Most of these insulation problems are accompanied by the presence of
partial discharges. In particular, the presence of partial discharges can be described by
PD inception/extinction voltages, PD amplitude and PD phase-resolved patterns. Performing
PD diagnostics several aspects are of importance:
- non-destructive for the cable insulation and uses AC voltage stress
conditions.
- uses standardised quantities.
- provides distinction between different types of insulation problems.
- provides PD site location: PD mapping.
It is known, that to obtain a sensitive picture of
discharging faults in power cables the PD should be ignited, detected and located at power
frequencies which are comparable to operating conditions at 50 or 60 Hz. In this way
realistic magnitudes in [pC]/[nC] and reproducible patterns of discharges in a power cable
can be obtained.
In this contribution PD detection, measurement and
analysis using oscillating wave test method is presented as new PD test procedure of
medium voltage PILC and polymeric insulated cables. In particular PD inception conditions,
PD magnitudes, PD phase-resolved patterns at slowly decaying voltages at different
oscillating frequencies (50Hz....500Hz) as well as the PD-location mappings are compared
for several insulation defects. In addition, based on systematic field experiences with
- PD diagnosis of existing cable systems
- After-repair testing of a cable system
- After-laying test of new cable systems
The general applicability of PD detection at oscillating
voltages will be discussed. (PowerPoint format 13 MB,
PDF format, 608 kB)
Spring 2000 - Basic Power
Cable Design
- Basic Power Cable Design - Carl C. Landinger,
Hendrix Wire & Cable, Abstract: Each component in a power cable has a specific
purpose. The application and environment dictate the necessity for, and importance of,
each component. The installation, application and environment may place additional demands
on one or several components resulting in the need to compromise the primary objective to
accommodate the additional demands. This course gives a brief overview of the need and
primary objective of each power cable component as well as some of the more common
compromises. (slides in PowerPoint97 format)
- Basic Electrical Characteristics, Carl C. Landinger,
Hendrix Wire & Cable, Abstract: By definition, power cables are utilized by the
application of voltage and current on the cable. The presence of voltage and current are
accompanied by separated charges and magnetic fields. These electrical parameters both act
upon, and are acted upon by, the cable materials and geometry. This course gives a brief
overview of the electrical characteristics of single conductor power cables and an even
more limited discussion of the impact of adjacent cables and facilities. At best, the
student is made aware of the more important characteristics in order to take them into
account when considering the specific case. (slides in
PowerPoint97 format)
- Basic Properties of Power Cable Insulations, Bruce S.
Bernstein, Electrical Power Research Institute (EPRI), Abstract: The
fundamentals of electrical insulation materials employed for wire and cable insulation
will be reviewed. This presentation, based on material included at the University of
Wisconsin's "Power Cable Engineering " course, reviews the fundamental nature of
polyolefins, defines crosslinking, antioxidants, crystallinity, and the role of mineral
fillers in polymers; how crosslinking is achieved as well as what it does to the polymer
structure and properties will be discussed along with differrences between water and
electrical trees. (slides in PowerPoint97 format)
Fall 1999 - Design
Principles for Cable Accessories (Separable Connectors, Joints and Terminations)
The Fall 1999 ICC Educational Program covered the basic principles
common to all cable accessory design. This includes electrical stress control both
geometric and Hi-K stress grading. Various types of current connections, compression,
spring and threaded were reviewed. The principles of interference fit both slip-on and
shrinkable were also examined. Two product specific areas, loadbreak connectors and
terminators were also covered. For loadbreak connectors, switching and fault-close design
criteria were reviewed. Terminator properties such as track resistance, hydrophobicity and
flashover distance were discussed.
- Electrical Stress Control - William Taylor, 3M
- Current Transfer - Michael Malia, T&B/Elastimold
- Interference Fit - John Makal, Cooper
- Terminator Considerations - William Taylor, 3M
- Switching - Frank Stepniak, T&B/Elastimold
This page last updated on
03/11/2008
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