Polypropylene Alternatives for Medium Voltage Cable Jackets

Transcription

1 Polypropylene Alternatives for Medium Voltage Cable Jackets Spring 2012 IEEE PES ICC Meeting Group A07D Selecting/Testing Jackets for Underground Cables March 27, 2012 Seattle, WA C.L. Flenniken 1

2 Outline Medium Voltage Cable Jacketing Background High Thermal Rated Jackets Polypropylene Resin Characteristics Comparison of Jacketing Materials Properties Summary 2

3 Medium Voltage Cable Jacketing Background Prior to 1980, underground medium voltage power cables were jacketed with PVC to reduce neutral corrosion and improve cable life Early 80 s LDPE jackets were introduced Since the mid 80 s, Linear Low Density Polyethylene (LLDPE) has been a primary jacketing resin for NA medium voltage distribution cables Europe has focused on MDPE and low shrinkage HDPE jacketing In early-90 s, PP jacketing was used for EPR medium voltage power cables for urban systems with restrictions associated with ducted systems and growing urban population 3

4 Background (Fall presentation in A07D) Benefits of Higher Thermal Rated (HTR) Jackets Neutral redesign results in lower amount of copper (<<$$) HTR Jacket + reduced neutrals cooler operation, lower line loss Improved thermo-mechanical In addition, HTR Jackets provide Opportunity to reduce wall thicknesses of cable design E.g. PP jacketed EPR insulated MV cables in ducts for urban installations 4

5 Proposed Specification for HTR Jackets Physical Properties Units Values UNAGED REQUIREMENTS Tensile Strength psi (MPa) > 1500 (>10.3) Break % > 150 AGED REQUIREMENTS (121 C for 168 hrs) Retained Tensile Strength % of original > 70% Retained Elongation % of original > 70% HEAT 131 C % < 30 CARBON BLACK % > 2.0 UL 1072 Standard recognizes XLPE jackets ANSI / ICEA and CSA proposals in progress 5

6 HTR Jacket Options Crosslinked Polyethylene (XLPE) jackets have initially been primary focus Moisture cured post extrusion Impacted by regional and seasonal temperature, relative humidity fluctuations and jacket wall thickness Polypropylene Alternative Commercially used for Ethylene Propylene Rubber (EPR) power cable jackets for > 15 years Good high temperature performance Can be optimized for low temperature performance on cable 6

7 Polypropylene Resin Characteristics Polypropylene resins (PP) deliver a broad array of engineering design options High crystallinity PP homopolymers Provide good strength to weight ratio Are resistant to many corrosive chemicals Endure abrasive treatment PP copolymers Can offer excellent flexibility Improve low temperature and impact performance 7

8 Polypropylene Resin Characteristics continued (SEM of etched surface to remove rubber phase) PP Low Rubber Rubber modified PP improves flexibility and low temperature properties PP High Rubber Continuous PP phase Etched Rubber Phase 8

9 Polypropylene Resin Characteristics continued Level, type and dispersion of rubber component in polypropylene copolymers impacts Stiffer and stronger Good low temperature performance with improved flexibility and impact properties Performance Flexibility Stiffer and Stronger 0 > >> >>> % Rubber in PP Copolymer 9

10 Comparison of HTR Jacket Materials Resins selected Linear Low Density Polyethylene (LLDPE) Impact Modified PP-A (PP-A) Impact Modified PP-B (PP-B) Moisture Cure Cross-linked Polyethylene (XLPE) Both plaques and wire evaluated (relative to test) Typical antioxidant packages added for air oven aging studies 10

11 Resin Physical Properties LLDPE PP-A PP-B XLPE Unaged* 1500 psi tensile; 150% elongation minimums Tensile, psi (MPa) Elongation, % * Testing on 14 AWG Solid Cu / 30 mil wall wire, no black masterbatch Heat Distortion, 30% maximum 100 C PASS PASS PASS PASS 136 C Melts PASS PASS PASS 150 C Melts PASS PASS PASS 11

12 Crush on Wire (no black master batch) 12

13 Toughness of Impact Modified Polypropylenes 13

14 Tailoring Rubber Content and Structure to Meet Performance 14

15 Modifications to PP Rubber Structure to Lower Modulus 15

16 Coefficient of Friction * Measured against HDPE extruded tape with no lubricant. 16

17 Comparison to Jacket Performance Requirements Unaged* Tensile, psi (MPa) TARGET LLDPE PP-A to B XLPE > Elongation, % > * Testing on 14 AWG Solid Cu / 30 mil wall wire Heat 136 C < 30% MELTS PASS PASS 17

18 Cable Manufacturer Benefits of Polypropylene Unlimited by curing process No pre-drying and no special extruder configuration Not impacted by ambient humidity As a thermoplastic, PP is recyclable 18

19 Summary Polypropylene has good high temperature performance PP jackets have been commercially used for medium voltage power cables for > 15 years Demonstrated performance in reduced wall wire constructions with good balance of physical and abuse resistant properties PP can be tailored for low temperature performance and flexibility Further investigation of Polypropylenes as HTR jackets 19

20 THANK YOU!! 20

21 Disclaimer All information ( Information ) contained herein is provided without compensation and is intended to be general in nature. You should not rely on it in making any decision. LyondellBasell accepts no responsibility for results obtained by the application of this Information, and disclaims liability for all damages, including without limitation, direct, indirect, incidental, consequential, special, exemplary or punitive damages, alleged to have been caused by or in connection with the use of this Information. LyondellBasell disclaims all warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose, that might arise in connection with this information.