Midwest Energy Association
16th Annual Electric Operations Technical
& Leadership Summit
Recent Developments in MV Cable
Materials
Dow Electrical & Telecommunications
Brent Richardson
May 2015
Dow.com
The Cable Value Chain
Feed-stocks
Base
Resin
Compound
Cable
Manufacturers
Utilities
Consumers
Regulators
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DOW CONFIDENTIAL - Do not share without permission
Insulation Manufacturing Process
Packaging
Bin
Resin/Additive
Feeder
Reactor
Mixing
Equipment
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Hopper Car
Uniclean
Package
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Insulation Compound Cleanliness Specifications
Cleanliness is critical:
• Contaminants reduce breakdown strength
• Contaminants act as electrical stress enhancers
Extra Clean (EC) insulation is recommended for MV applications with a
specifications of no more than 2 contaminants between 127 and 254
mm, and zero contaminants greater than 254 mm (per 1.6 kg basis)*
Super Clean (SC) insulation is recommended for HV/EHV up to 230 kV
applications with a specification of zero contaminants greater than 100
mm (per kg basis)
EHV insulation is recommended for EHV above 230 kV with a
specification of zero contaminants greater than 70 mm (per kg basis)
* European EC specs allow 3 contaminants between 100 and 200 mm and zero contaminants greater than 200mm
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Insulation Compound Cleanliness Camera Tape
Contamination Test System
Clean Room (Class 10,000)
Clean Box
(Class 1000)
Labeler
Camera
Box
T-Die
Extruder
Tape
Take-up Roll
Detector
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Insulation Manufacturing Product Packaging
EC for MV
packaged into railcars
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SC for HV
packaged into
boxes
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Insulation Types for Medium Voltage Cables
The Insulated Conductors Engineering Association
(ICEA) recognizes four types of material for the
purpose of providing insulation for MV cables
•Cross Linked Polyethylene (XLPE)
•Tree Retardant Cross Linked Polyethylene (TR-XLPE)
•Ethylene Propylene Rubber (EPR)
•Ethylene Alkene Copolymer (EAM)
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Chronology of TR-XLPE Insulation
1983 – Market Introduction by Union Carbide
First commercial TR-XLPE insulation with demonstrated long
life performance-HFDA-4202
1998 – Processing Improvements Provided
Maintained the excellent electrical performance of the A4202
with improved properties for more robust cable manufacturingHFDB-4202
2001-Competitive Materials Introduced
Borealis enters the NA market with LE-4212
2010 – Longer Life Materials Introduced
Advancements to enhance longer life, ease of installation
and further manufacturing robustness to ensure quality
and consistency-HFDC-4202
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TR-XLPE Insulation Components
Polyethylene
Tree Retardant
Antioxidant package
Cure System
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Chronology of EPR Insulation
1955 – Polymer Technology Developed
Carl Ziegler developed a novel catalyst for polymerization of ethylene to
polyethelyne-copolymerizing ethylene with propylene yields a new
elastomer, EPM
Early 1960’s– EPM Compound Production Begun
1962- Cable Applications Begun
Late 1960’s- Compounded EPDM introduced for
Crosslinking Attributes
1970’s-Broad Molecular Weight Distribution improves
processing
1990’s-Development of Mettalocene Catalyst Technology
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EPR Insulation Components (typical formulation)
Elastomer
Kaolin clay
Antioxidant package
Vinyl Silane
Heat Stabilizer
Red Lead
Wax
Low Density Polyethylene
Dicumyl Peroxide
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TR-XLPE & EPR Insulation materials
Generic Material Properties
TR-XLPE
EPR
• Unfilled
• Highly filled material
• Pure, simple polymer
• Complex mixtures
• Extra clean, natural
• Cannot see contaminants
• Dry cure
• Steam cure
• True-triple extrusion
• Mostly 2+1 extrusion
• Clean interfaces
• More interfacial stress risers
• Higher aged electrical strength
• Lower aged electrical strength
• Deformation resistant
• Deformation resistant
• Tougher
• Softer / more flexible
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NEETRAC 35 KV Test Results
Nominal AC Breakdown Strength (V/mil)
1000
900
Cable Design Aging Test
NEETRAC Project Number 97-409
AC Breakdown Results
Averages, 345 Mil Wall
New and Aged 4 Years @ 90 & 45 Deg. C, 69 kV
924
924
948
860
860
844
764 780
800
724
700
564
600
560
476
500
476
500
452 467
372
400
404
TR-XLPE 1
TR-XLPE 2
300
TR-XLPE 3
200
TR-XLPE 4
100
EPR 1
EPR 2
0
New
90° C
45° C
Note: The insulation shield used on EPR1was found to be incompatible with the insulation at the elevated conductor temperature of 90 Deg. C
This graph is a compilation of data from various figures included in NEETRAC Baseline Project Report 97-409. It was prepared and provided under Clause 6 of the terms and
conditions outlined in the NEETRAC Publication Policy on the use of Baseline Project Results/Data. In keeping with that policy, the graph was reviewed and approved by
NEETRAC and only Dow Chemical products can be identified outside the NEETRAC Membership.
It is also important to note that ac breakdown was one of several tests used to evaluate the performance of complete cable designs in this accelerated aging test program.
While comparing average ac breakdown strength values provides some insight into cable performance differences (or similarities), a statistical analysis/review of all measured
performance values and characteristics is required to provide a complete indication of performance.
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EAM Background
 The medium voltage filled insulation market has been dominated by
Ethylene Propylene Rubber (EPR) based “leaded” insulations for the
last forty (40) years
 The solution for increasing cable performance, dealing with
environmental concerns, and addressing changing market dynamics
requires modifications to the insulation system’s base polymer and
stabilization package
 Over the last ten (10) years the performance of metallocene
catalyzed Ethylene-Alkene Copolymers (EAM’s) have improved
significantly; in concert with stabilizer package development, leadfree EAM insulation meeting utility MV performance requirements
has been created
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Definition of Insulation Materials per ANSI/ICEA

ANSI/ICEA S-94-649 and S-97-682 allow alternate EAM insulating materials meeting
the same physical and electrical requirements of XLPE, TRXLPE, and EPR

EAM materials are first identified in a footnote under Table 4-1 in ANSI/ICEA S-94-649
and S-97-682 and are further explained in Appendix I and Appendix H respectively.
EAM materials have been listed since 1996
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Definition of Insulation Materials per ANSI/ICEA
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Why Elastomers are Used in MV Cable
Applications

Elastomers are polymers that exhibit high extension and flexibility
when placed under low mechanical stress

Low crystallinity of elastomers permit excellent flexibility that
enables ease of cable installation

Low crystallinity of elastomers require higher filler incorporation that
in turn permits cross linked compounds to exhibit high heat and oil
resistance
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LF Filled EAM Insulation for Cable Applications

Continuing technological developments in polymer catalyst technology
make available more diverse polymers suitable for medium voltage cable
applications

General Cable developed LF Filled EAM with a Dow elastomer which uses
the traditional ethylene backbone of an EPR formulation, but with a longer
side chain

The increasing side chain lengths in EAM compounds improves flexibility
and the resulting electrical performance is improved without lead



Ease of installation: Improved flexibility and trainability; Less spring-back
Environmental sustainability is gained and recyclability is improved
LF Filled EAM retains the inherent benefits of EPR insulations with
improved thermal stability
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Why Lead-Free?
 With safety as a top concern, the industry has focused on removing
hazardous materials from cable products
 RoHS, California Prop. 65, REACH all restrict lead use; EPA
currently says that the lead content in MV EPR insulation is below
threshold limit, but what will be the future limits?
 > 250,000 lb of red lead oxide used in MV EPR insulation production
by one manufacturer per year; Each year as the volume of
traditional EPR consumption keeps growing the amount of red lead
oxide grows
 ≈ 43 lb of red lead oxide per circuit mile of 4/0 Al 220 mils wall EPRinsulated MV cable
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LF Filled EAM Insulation Cable Testing
Flexibility Testing
Lead-Free EAM
Leaded EPR
Lead-Free EAM is more flexible than Leaded EPR;
33% reduction in flex modulus when compared to semicrystalline
Leaded EPR.
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Comparison of Insulation Materials
The chart below compares key attributes of MV cables for each of the
three major insulation types
Cable Attribute
Insulation by Type
TR-XLPE
EPR
EAM
Greater flexibility for ease of installation
C
B
A
Environmental Sustainability
A
C
A
Recyclability
B
C
B
Suitability for constrained space
C
B
A
105/140 C insulation rating
A
A
A
Dielectric losses (dissipation factor)
A
C
B
Highest Retained Breakdown Strength (AWTT)
A
C
B
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Features & Benefits of EAM Insulated Cables
 Lead-Free Filled EAM compounds offer improved installation
performance and an environmentally conscious alternative for
demanding MV Utility insulation applications
 Lead-free Filled EAM has demonstrated thermal, wet & dry electrical
stability
 Improved flexibility; Improved trainability and less spring-back
o Easier handling during installations
o Appealing for the installation crew; Better ergonomics; Less fatigue after handling
 Better wet electrical aging performance vs. a Leaded EPR as
demonstrated by AWTT and ACLT testing
 Meets or exceeds ANSI/ICEA S-94-649 & S-97-682 and AEIC CS8
 A “Green” Sustainable Solution
o Eliminates the last hazardous material from MV cable designs
o Low and stable dissipation factor (lower losses) at elevated temperatures
o Green solution may aid in rate case approvals
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Summary
 Today’s MV insulations have positive and negative
attributes and should be evaluated based on the utility
need
 Continued research and development of materials and
manufacturing methods has produced longer lasting
cables for the industry
 Update your cable specification and consider the
purchase of cables that best meet your specific
application
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Brent Richardson
brichardson@dow.com
704-721-0288
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