Recent Developments in MV Cable Materials
Transcript of Recent Developments in MV Cable Materials
Dow.com
Dow Electrical & Telecommunications
Brent Richardson
May 2015
Recent Developments in MV Cable
Materials
Midwest Energy Association
16th Annual Electric Operations Technical
& Leadership Summit
The Cable Value Chain
Feed-stocks Compound Cable
Manufacturers Utilities Consumers
Regulators
2
DOW CONFIDENTIAL - Do not share without permission
Base Resin
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
Packaging Bin
Hopper Car
Resin/Additive Feeder
Uniclean Package
Reactor
Mixing Equipment
Insulation Manufacturing Process
3
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
Insulation Compound Cleanliness Specifications
4
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
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
Insulation Compound Cleanliness Camera Tape Contamination Test System
5
Clean Room (Class 10,000)
T-Die
Labeler
Clean Box
(Class 1000)
Take-up Roll
Tape
Camera
Box
Extruder
Detector
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
Insulation Manufacturing Product Packaging
6
EC for MV
packaged into railcars
SC for HV
packaged into
boxes
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
Insulation Types for Medium Voltage Cables
7
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)
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 8
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 manufacturing-
HFDB-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
8
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
TR-XLPE Insulation Components
9
Polyethylene
Tree Retardant
Antioxidant package
Cure System
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 10
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
10
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
EPR Insulation Components (typical formulation)
11
Elastomer
Kaolin clay
Antioxidant package
Vinyl Silane
Heat Stabilizer
Red Lead
Wax
Low Density Polyethylene
Dicumyl Peroxide
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
TR-XLPE & EPR Insulation materials
TR-XLPE
• Unfilled
• Pure, simple polymer
• Extra clean, natural
• Dry cure
• True-triple extrusion
• Clean interfaces
• Higher aged electrical strength
• Deformation resistant
• Tougher
EPR
• Highly filled material
• Complex mixtures
• Cannot see contaminants
• Steam cure
• Mostly 2+1 extrusion
• More interfacial stress risers
• Lower aged electrical strength
• Deformation resistant
• Softer / more flexible
Generic Material Properties
12
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 13
924
844
724
860
564
500
924
476
372
948
860
452
764
560
467
780
476
404
0
100
200
300
400
500
600
700
800
900
1000
New 90° C 45° C
No
min
al A
C B
rea
kd
ow
n S
tren
gth
(V
/mil
)
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
TR-XLPE 1
TR-XLPE 2
TR-XLPE 3
TR-XLPE 4
EPR 1
EPR 2
Note: The insulation shield used on EPR1was found to be incompatible with the insulation at the elevated conductor temperature of 90 Deg. C
NEETRAC 35 KV Test Results
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.
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 14
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, lead-
free EAM insulation meeting utility MV performance requirements
has been created
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 15
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
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 16
Definition of Insulation Materials per ANSI/ICEA
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 17
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
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
LF Filled EAM Insulation for Cable Applications
18
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
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 19
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 EPR-
insulated MV cable
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 20
LF Filled EAM Insulation Cable Testing
Lead-Free EAM is more flexible than Leaded EPR; 33% reduction in flex modulus when compared to semicrystalline
Leaded EPR.
Flexibility Testing
Lead-Free EAM
Leaded EPR
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 21
Comparison of Insulation Materials
The chart below compares key attributes of MV cables for each of the
three major insulation types
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
Insulation by TypeCable Attribute
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 22
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
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 23
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
®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow 24
Brent Richardson
704-721-0288
24