Doble Tutorial - Medium Voltage Power Cables and Accessories
Short Description
Download Doble Tutorial - Medium Voltage Power Cables and Accessories...
Description
TUTORIAL: MEDIUM VOLTAGE POWER CABLES AND ACCESSORIES 2011 International Conference of Doble Clients
Thursday, March 31, 2011 7:30 AM – 12:00 PM Westin Copley Place Hotel America North, 4th Floor
Doble Client Conference: ICEA Standards Review
March 31, 2011
Insulated Cable Engineers Association (ICEA) Standards Review
Doble Client Conference: ICEA Standards Review
March 31, 2011
I. Overview of ICEA Energy Division – Power Cable Section II. Industry Wide Input & Standards Coordination III. ICEA Cable, Test & Application Standards That Apply To Power Cables IV. Navigating The ICEA Website
Doble Client Conference: ICEA Standards Review
March 31, 2011
Overview of ICEA ¾ Composed strictly of engineers who are employed by cable manufacturing companies. ¾ These companies are sponsors of the association. ¾ Members cannot be involved in sales, pricing or order placement. ¾ IPCEA was formed in 1925 by a group of power cable engineers. ¾ Evolved into 3 separate sections – Control & Instrumentation Cables, Power Cables & Portable Power Cables. ¾ In 1979 Communication Cables were added and the name was changed to Insulated Cable Engineers Association (ICEA).
1
Doble Client Conference: ICEA Standards Review
March 31, 2011
Overview of ICEA ¾ The organization was later reorganized into two Divisions ¾ Energy Cables ¾ Communications Cables ¾ The Energy Cables Division retained ¾ Control & Instrumentation (C&I) ¾ Power ¾ Portable ¾ The Communication Cables Division was further subdivided into ¾ Copper ¾ Fiber
Doble Client Conference: ICEA Standards Review
March 31, 2011
Overview of ICEA ¾ The association meets quarterly in March, June, September and December. ¾ The association maintains a website at ICEA.net ¾ The association is a “Not-For-Profit” organization who’s sole support is from member dues & fees and standards sales. ¾ Since 1925 the objective has been to ensure safe, economical and efficient cable systems utilizing proven state-of-the-art materials and concepts.
Doble Client Conference: ICEA Standards Review
March 31, 2011
Industry Wide Input & Standards Coordination ¾ The Utility Power Cable Standards Technical Advisory Committee UPCSTAC was formed in 1996. ¾ Outgrowth of a long felt need for a comprehensive, national standard for concentric neutral power cable. ¾ UPCSTAC membership is comprised of ¾ ICEA Power Cable Section members ¾ AEIC Cable Engineering Committee members ¾ The primary documents covered by UPCSTAC are for Medium and High Voltage Utility Power Cables. ¾ The documents are also reviewed by IEEE Insulated Conductors Committee (ICC) and American National Standards Institute (ANSI)
2
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables
Test Standards
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables Test Standards include: ¾ ANSI/ICEA T-24-380 Standard for Partial-Discharge Test Procedure ¾ ICEA T-25-425 Guide for Establishing Stability of Volume Resistivity for Conducting Polymeric Compounds of Power Cables ¾ ANSI/ICEA T-26-465 Guide for Frequency of Sampling Extruded Dielectric Cables ¾ ANSI/ICEA T-28-562 Test Method for Measurement of Hot Creep of Polymeric Insulation ¾ ANSI/ICEA T-27-581 Test Methods for Extruded Dielectric Cables
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables Test Standards include: (continued) ¾ ANSI/ICEA T-31-610 Test Method for Conducting Longitudinal Water Penetration Resistance Tests on Blocked Conductors ¾ ICEA T32-645 Guide for Establishing Compatibility of Sealed Conductors with Conductor Stress Control Materials ¾ ICEA T-33-655 Low Smoke, Halogen-Free Polymeric Jackets ¾ ANSI/ICEA T-34-664 Test Method for Conducting Longitudinal Water Penetration Resistance Tests on Longitudinal Blocked Cables
3
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables
Application Standards
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Applications Standards for Power Cables Application Oriented Standards include: ¾ ANSI/ICEA P-32-382 Short-Circuit Characteristics of Insulated Cable ¾ ICEA P-54-440 Ampacities of Cables in Open-Top Trays ¾ ANSI/ICEA P-45-482 Short-Circuit Performance of Metallic Shields & Sheaths ¾ ANSI/ICEA P-79-561 Guide for Selecting Aerial Cable Messengers & Lashing Wires
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables
Non-shielded Cable Standards
4
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables Non-shielded Cable Standards include: ¾ ANSI/ICEA S-76-474 Neutral Supported Power Cable Assemblies with Weather-Resistant Extruded Insulation Rated 600 Volts ¾ ANSI/ICEA S-70-547 Weather Resistant Polyethylene Covered Conductors ¾ ANSI/ICEA S-81-570 600 Volt Rated Cables of Ruggedized Design for Direct Burial Installations as Single Conductors or Assemblies of Single Conductors
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables Non-shielded Cable Standards include: (continued) ¾ ANSI/ICEA S-95-658 Non-Shielded Power Cables Rated 2000 V or Less ¾ ICEA S-96-659 Non-Shielded Power Cables Rated 2001 – 5000 V ¾ ANSI/ICEA S-105-692 600 Volt Single Layer Thermoset Insulated Utility Underground Distribution Cables
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables
Shielded Cable Standards
5
Doble Client Conference: ICEA Standards Review
March 31, 2011
Cable, Test & Application Standards for Power Cables Shielded Cable Standards include: ¾ ANSI/ICEA S-93-639 Shielded Power Cables 5,000 – 46,000 V ¾ ANSI/ICEA S-94-649 Concentric Neutral Cables Rated 5 Through 46 kV ¾ ANSI/ICEA S-97-682 Utility Shielded Power Cables Rated 5 Through 46 kV ¾ ANSI/ICEA S-109-720 Extruded Insulation Power Cables Rated Above 46 kV Through 345 kV
Doble Client Conference: ICEA Standards Review
March 31, 2011
Working Groups for New Standards • WG 684 Performance Based Utility 5 – 46 kV • WG 726 Pellet Inspection Systems • WG 728 Non-Metallic Shielded Mining Cables • WG 733 Tree Wire and Spacer Cable • WG 734 New Electric Distribution Ampacity Tables
Doble Client Conference: ICEA Standards Review
March 31, 2011
Navigating The ICEA Website
6
Doble Client Conference: ICEA Standards Review
March 31, 2011
We reorganized the ICEA Web site at http://www.icea.net to make it easier to find the Standard you need. • Added a “New & Recently Added Documents” Direct Link • Separated Energy & Communication Documents • Divided Energy Documents into: • Power Cable • Portable Cable • Control & Instrumentation (C&I) Cable • Added a Preview & Purchase Link for Each Document • Cover, Table of Contents, Scope
Doble Client Conference: ICEA Standards Review
March 31, 2011
INSULATED CABLE ENGINEERS ASSOCIATION, Inc.
About ICEA The Insulated Cable Engineers Association (ICEA) is a professional organization dedicated to developing cable standards for the electric power, control, and telecommunications industries. Since 1925, the objective has been to ensure safe, economical, and efficient cable systems utilizing proven state-of-the-art materials and concepts. Now with the proliferation of new materials and cable designs, this mission has gained in importance. ICEA documents are of interest to industry participants worldwide, i.e. cable manufacturers, architects and engineers, utility and manufacturing plant personnel, telecommunication engineers, consultants, and OEM'S. ICEA is a "Not-For-Profit" association whose members are sponsored by over thirty of North America's leading cable manufacturers. The technical development work is performed in four semi-autonomous Sections; namely, the Power, Control & Instrumentation, Portable, and Communications Cable Sections. In addition there are currently two very active major Technical Advisory Committees, one for Telecommunications Wire and Cable Standards (TWCS TAC) and another Utility Power Cable Standards (UPCS TAC).
Doble Client Conference: ICEA Standards Review
March 31, 2011
INSULATED CABLE ENGINEERS ASSOCIATION, Inc.
ICEA Engineering Documents It is ICEA's mission to keep these standards up-to-date on a continuing basis. These Documents may be purchased through IHS. ICEA Standards fall into four categories:
Refer to our Ordering Info page for purchasing details.
Back
7
Doble Client Conference: ICEA Standards Review
March 31, 2011
INSULATED CABLE ENGINEERS ASSOCIATION, Inc.
New & Recently Added Documents These standards were developed by the Insulated Cable Engineers Association, Inc. (ICEA), within the past 3 years. These Documents may be purchased through IHS. You may view the first pages including the Table of Contents for some documents by clicking on the Preview Documents link and/or purchase them by clicking on the Purchase Now link. Not all documents have previews available.
Energy Cable Standards ANSI/ICEA T-24-380-2007 Guide For Partial-Discharge Test Procedure $60.00 Preview Document Purchase Now
Doble Client Conference: ICEA Standards Review
March 31, 2011
INSULATED CABLE ENGINEERS ASSOCIATION, Inc.
Doble Client Conference: ICEA Standards Review
March 31, 2011
INSULATED CABLE ENGINEERS ASSOCIATION, Inc.
Energy Documents
Back
8
Doble Client Conference: ICEA Standards Review
March 31, 2011
Thanks For Including ICEA In Your Conference & Any Additional Questions
9
AEIC Cable Engineering Committee Specifications, and Guides by Mike Smalley – We Energies, Chair, AEIC Cable Engineering Committee
Doble Conference – March 31, 2011 1
Association of Edison Illuminating Companies (AEIC)
Established in 1885 by Thomas Edison Members are electric utilities, generation companies, transmission companies, and distribution companies – internationally. Through a committee structure, the Association addresses technological problems associated with planning, building and operating an electric utility system.
2
AEIC (Cont) Includes investor-owned, federal, state, cooperative, and municipal systems Associate members include organizations responsible for technical research and for promoting, coordinating, and ensuring the reliability and efficient operation of the bulk power supply system (e.g. EPRI).
3
1
AEIC Committees
The AEIC's six committees are staffed with experts from management of member companies and meet regularly during the year to explore issues in their particular areas:
Load
Research and Service
Power Apparatus
Power Delivery
Power Generation
Cable Engineering
Meter
4
Cable Engineering Committee (CEC)
28 Members and 2 Technical Advisors
Cable
Engineers from Electric Utilities from Research Labs and Organizations
Engineers
5
CEC Purpose
The purpose of the CEC is to develop and maintain specifications and guides for electric utility cable system design, maintenance, and operations. 7 Specifications 11 Guidelines 6
2
CEC Procedures
Goals:
Reaffirm,
Revise, or Withdraw specifications every 5 years
Reaffirm, Revise, or Withdraw guides every 7 years
A Task Group chair, Vice Chair, and TG members are assigned to each document Once complete, documents are balloted within the task group. After TG approval, the whole CEC is balloted 7
Outline for All Cable Specs Conductor Conductor Shield Insulation Insulation Shield Metallic Shielding Moisture Barrier Jacket
8
Outline for All Cable Specs (Cont) Cable Identification Production Test Procedures Shipment and Reels Guarantee Tests During and After Installation
9
3
CEC Paper (Laminar) Cable Specs
These Specifications are considered to be the industry standard (there is no NEMA, ANSI or ICEA cable standard associated with them):
CS1-90
PILC High Pressure Pipe Type
CS3-90 Low Pressure Gas-Filled Type
CS4-93 Low and Medium Pressure Self-Contained Liquid Filled Cable
CS31-95 Pipe Filling Liquids
CS2-97
10
CEC Extruded Dielectric Cable Specs
CS5, Obsolete, replaced by CS8 CS6, Obsolete, replaced by CS8 and CS9 CS7, Obsolete, replaced by CS9 CS8-07 Extruded Dielectric 5-46 kV, supplements:
NEMA WC74/ICEA S-93-639 (Shielded Power Cables 5-46 kV) ICEA S-94-649 (Medium Voltage CN cables) ICEA S-97-682 (Utility Shielded Power Cables 5-46 kV)
CS9-06 Extruded Dielectric Cables and Their Accessories Rated Above 46 kV through 345 kV AC, supplements:
ICEA S-108-720 (Extruded Power Cables 46-345 kV)
11
CEC Guides
CG1-96 Maximum Temperatures for PaperInsulated Cables, use with:
CG3-05 Installation of Pipe-Type Cable Systems, use with:
CG4-97 Installation of Extruded Dielectric Cables 69-138 kV, use with:
CG5-05 Extruded Power Cable Pulling, use with:
CS1
through CS4
CS2
CS9
CS8,
CS9, ICEA S-81-570, S-95-658, S-94-649, S96-659, S108-720, T-33-655 12
4
CEC Guides (Cont)
CG6-05 Maximum Temperatures of Extruded Dielectric Cables, use with:
CS8,
CS9, S-94-649, S-97-682, S-108-720, S-93-639
CG7-05 Replacement and Life Extension of Extruded Dielectric 5-35 kV Cables, use with:
CS8,
S-94-649, S-97-682 13
CEC Guides (Cont)
CG8-03 Electric Utility Quality Assurance Program for Extruded Dielectric Cables, use with:
CG9-00 Installing, Operating, and Maintaining Lead Covered Cables 5-46 kV, use with:
CG10-02 Developing Specs for Extruded Cables 5-46 kV, use with:
CS8,
CS1,
CS9, S-94-649, S-97-682, S-93-639, S-108-720
CS2, CS3, CS4, and CS8
CS8
14
CEC Guides (Cont)
CG11-02 Reduced Diameter Extruded Dielectric Cables 5-46 kV, use with:
CS8,
S-94-649, S-97-682, S-XX-684 (future)
CG12-05 Minimizing the Cost of Extruded Dielectric Cables 5-46 kV
CS8,
S-97-682, S-94-649, S-93-639
15
5
CS1-90 PILC Cable
Specification for Impregnated PaperInsulated MetallicSheathed Cable, Solid-Type
11th
Edition, October 1990
Revision in progress
16
CS1-90 Scope This specification applies to impregnated paper-insulated, metallic-sheathed cable of the "solid" type which is to be used for the transmission and distribution of electrical energy on electric utility systems. Cables Rated 1 kV to 69 kV
17
CS1-90 Scope
The term solid-type cable designates a hermetically sealed type of massimpregnated cable having an essentially solid cross-section impregnated with a saturant of suitable viscosity, and designed for operation without a pressure medium.
18
6
CS2-97 High Pressure Pipe-Type Cable
Specification for Impregnated Paper and Laminated Paper Polypropylene Cable, High Pressure PipeType
6th
Edition, March 1997
Revision in progress
19
CS3-90 Low Pressure Gas Filled Cable
Specification for Impregnated Paper Insulated Metallic Sheathed Cable, Low Pressure Gas Filled-Type
3th
Edition, October 1990 in progress
Revision
20
CS4-93 Self Contained Liquid Filled Cable
Specification for Low and Medium pressure SCLF cable
8th
Edition, January 1993
Revision in progress
21
7
CS8-07 Extruded Cable 5-46 kV
Specification for Extruded Dielectric, Shielded Power Cables Rated 5 Through 46 kV
3rd
34
Edition, February 2007 pages
22
CS8-07 Scope Supplements ANSI/ICEA S-94-649 and S-97-682 This specification covers cables rated 546 kV, which are used for the distribution of electric energy on electric utility systems.
23
CS8-07 Additional Items Qualification Tests Appendixes
Industry
Specifications, Standards, and References
History of Cable Diameters
Procedure for Determining Diameters of Cables
ANSI/ICEA Tables 24
8
CS8-07 Additional Items
Partially replaced CS5 and CS6 (covers both EPR and XLPE/TRXLPE cables):
CS5
CS6
covered XLPE insulated cables from 5-46 kV
Originally published: 1969
covered EPR insulated cables from 5-69 kV
Originally published: 1972
ANSI/ICEA standards have provided a way to greatly simplify the AEIC specifications. The 2007 version largely adopted ICEA cable diameters; which use lower minimum point thicknesses... Example next page-> 25
Insulation Thickness Comparisons 175-mil average (previous AEIC) 176
158
190 max
min
176
26
Insulation Thickness Comparisons min-max (ANSI/ICEA)
165 min
205 max
27
9
Example Install two joints and a short piece of new cable into section of failed old cable Both cables 1000 kcmil 260 mil 25 kV Old cable manufactured in 1979 to AEIC CS5-79 Specification New cable manufactured to ANSI/ICEA Standard
28
CS8-00 Ranges of 1000 kcmil 25 kV Cable and Three Joints 1710
AEIC
1645
ANSI/ICEA
95
X 1515
265
1665
Y
120
1660
Z 1500
60
1550
1600
160
1650
1700
1750
1800
1850
Diameter in mils 29
CS8-07 Some Differences from 649 Includes “Guarantee” section Includes Field Strippability Test Shipment and Reels Tree Count Test
30
10
CS9-06 Extruded Cables and Accessories rated 46-345 kV
Specification for Extruded Insulation Power Cables and their Accessories rated above 46 kV Through 345 kV AC
1st
64
Edition, December 2006 pages
31
CS9-06 Background Info.
Partially replaced CS6 and CS7:
CS6 Covered EPR insulated cables from 5-69 kV
CS7 covered XLPE insulated cables from 69-138 kV
Originally published: 1972 Originally published: 1982
The first AEIC specification covering a complete cable system including joints/terminations Covers both EPR and XLPE/TRXLPE cable systems A system specification, not just a cable standard Some differences from S-108-720 in conductor shield material and in the number and size of voids in the insulation 32
CS9-06 Contents
General Cables Terminations Joints Sheath Bonding/Grounding Systems, Link Boxes, and SVL’s Qualification Tests on System Prequalification Tests on System Electrical System Test After Installation Quality Assurance Shipping Appendices (informative) 33
11
CEC Guidelines In the early days of the cable industry, no other guidelines were available within the industry concerning cable operations, installation, and maintenance. CEC decided to begin developing some guidelines for utilities to use.
34
Temperature Guides CG1 and CG6 CG1 – PILC Cables CG6 – Extruded Dielectric Cables Emergency Operations and Temperature Limits Principles and Basic Background Factors Limiting Factors Determination of Ampacity
35
CG1-07 PILC Temperatures
Guide for Establishing the Maximum Operating Temperatures of ImpregnatedPaper- and Laminated-PaperPolypropylene-Insulated Cable
4th
Edition, June 2007
Scope: Operating temperature limits for transmission and distribution paper and paper-polypropylene insulated cable. 36
12
CG6-05 Extruded Cable Temperatures
Guide for Establishing the Maximum Operating Temperatures of Extruded Dielectric Insulated Shielded Power Cables
2nd
Edition, November 2005
37
CG6-05 Scope This guide primarily covers temperatures limits for extruded dielectric cable in underground installations. Some guidance is provided for other applications such as aerial installations and riser pole applications.
38
CG5-05 Extruded Cable Pulling
Underground Extruded Power Cable Pulling Guide
2nd
Edition, June 2005
39
13
CG5-05 Scope Outlines the pulling parameters that need to be considered when installing underground power cable in duct. Based on EPRI Project EL-3333 “Maximum Safe Pulling Lengths for Solid Dielectric Insulated Cables” Some sidewall pressure and tension recommendations differ from those of cable manufacturers
40
CG5-05 Scope (Cont) Pulling guides and computer software are available from many cable manufacturers and lubricant manufacturers. Several of these guides provide a basic introduction to cable pulling criteria. Some of these manufacturers’ guides are listed in the bibliography. CG5 is intended to complement these publications.
41
CG5-05 Scope (Cont)
The major points covered in the guide include:
Factors
that influence pulling tensions such as cable type, conduit type and size, lubricants, and installation practices
Calculation of maximum pulling lengths allowable without damaging the cable
Limits on cable tension and sidewall bearing pressure 42
14
CG5-05 Contents Cable Removal Economic Considerations Design Criteria and Pulling Limits Pulling Tension Formulae Sidewall Bearing Pressure Formulae Sample Calculations References
43
CG7-05 Extruded Cable Replacement 5-35 kV
Guide for Replacement and Life Extension of Extruded Dielectric 5-35 KV Underground Distribution Cables
2nd
Edition, November 2005
44
CG7-05 Scope Covers extruded dielectric utility distribution system cables rated 5-46 kV Includes options for cable replacement and cable life extension based upon current options within the industry today.
45
15
CG7-05 Contents Identifying Problem Cable Systems Decision Making Tools Selection and Implementation of Solution or Corrective Action Reliability and System Enhancements to Reduce Cable Failures
46
CG8-10 Quality Assurance Extruded Cables 5-46 kV
Guide for Electric Utility Quality Assurance Program for Extruded Dielectric Power Cables
3rd
Edition, August 2010
47
CG8-10 Scope Techniques and procedures that an electric utility may use to establish a quality assurance program for extruded dielectric power cable Helps to ensure that the utility consistently receives cable with the characteristics it desires
48
16
CG8-10 Contents The Utility Cable Specification Manufacturing Plant Audits Cable Inspection and Testing Keeping Records of Installation and Operating Experiences Outline of a Cable Specification Manufacturer Questionnaire Inspection List
49
CG9-00 Installing and Operating Lead Covered Cable 5-46 kV
Guide for Installing, Operating, and Maintaining Lead Covered Cable Systems Rated 5 kV Through 46 kV
1st
Edition, May 2000
Reaffirmed in 2008
50
CG9-00 Scope Lead-covered cables have been in use for over 80 years and have demonstrated exceptional service reliability. Two of the most common constructions in use are paper-insulated lead-covered cable (PILC) and lead-covered extruded-dielectric cable.
51
17
CG9-00 Scope (Cont) Dealing with the lead on these types of cables has become costly due to Federal and State safety regulations. Consequently, the use of lead covered cables has declined and the expertise needed to install and maintain them has declined as well.
52
CG9-00 Scope (Cont)
This guide is intended to outline generally accepted installation, operation, and maintenance practices for lead covered cables.
53
CG9-00 Contents Manholes Cable Handling Cable Installation in Duct and Direct Buried Cable Accessories (Joints and Terminations) Grounding Identification and Installation Records Inspection and Maintenance
54
18
CG10-10 Developing Specs for Extruded Power Cables 5-46 kV
Guide for Developing Specifications for Extruded Power Cables Rated 5 through 46 kV
2nd
Edition, December 2010
55
CG10-10 Scope This guide describes the various choices that an engineer must consider when developing a medium voltage (5-46 kV) cable specification for utility use. It is designed to acquaint the user with those criteria necessary to ensure the cable will perform as intended.
56
CG10-02 Contents
The contents of CG10 basically follows the outline of CS8 (MV Cable Spec) and CS9 (HV Cable Spec)
57
19
CG11-02 Reduced Diameter Extruded Dielectric Cables 5-46 kV
Guide for Reduced Diameter Extruded Dielectric Shielded Power Cables Rated 5 Through 46 kV
1st
Edition, January 2002
58
CG11-02 Scope Replacing smaller PILC cables in existing, space-limited infrastructure. Provides general information to be used when specifying and using cables with reduced diameters.
59
CG11-02 Contents
Design Variables
Insulation
Jacket
Metallic Shield (Flat Strap or Longitudinally Corrugated Tape)
Insulation Shield
Center Conductor
Conductor Shield 60
20
CG11-02 Contents (Cont)
Operating Conditions
Maximum
Conductor Temperatures Operating Temperatures
Metallic Shield Short Circuit Rating
Ampacity Requirements
Emergency
61
CG11-02 Contents (Cont)
Field Considerations
Duct
Clearances Configurations
Terminations and Joints
Pulling Methods
Cable Handling
Proof Testing
Duct
62
CG12-05 Minimizing the Cost of Extruded Cables 5-46 kV
Guide for Minimizing the Cost of Extruded Dielectric Shielded Power Cables Rated 5 through 46 kV
1st
Edition, June 2005
63
21
CG12-05 Scope This guide provides general information that can be used to minimize the initial purchase cost of extruded dielectric cable rated 5-46 kV. The variables allow the user to be aware of some options to consider when attempting to reduce the initial purchase cost of their cable.
64
CG12-05 Contents
Design Variables
Insulation
Jacket
Insulation Metallic Shield Shield (Concentric Neutral or (Semicon) Tape Shield)
Center Conductor (Strand-filled) Conductor Shield
65
CG12-05 Contents (Cont) Labeling Packaging Production Tests Quality Assurance Documentation Qualification Tests Industry Specifications, Standards, Guides, and Contact Information
66
22
Conclusions
Standards and Specifications affect every aspect of how we design our cable systems. Many Standards and Specifications are interrelated. Individual Company specifications should coordinate with these industry standards for an optimal cable system design. Industry Guides may be used to gain greater insight into the application of the cable system 67
Standards, Specs, and Codes A technical standard is an established norm or requirement. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes, and practices. A specification is an explicit set of requirements to be satisfied by a material, product, or service
Wikipedia.org
68
Standards, Specs, and Codes (Cont) Codes are rules established or adopted by a governmental agency, required to be followed. Codes represent the minimum acceptable requirements. Governmental agencies usually obtain adherence to codes by requiring permits.
69
23
Standards and Specifications Affecting Cable Systems American National Standards Institute (ANSI) ASTM International (ASTM) Institute of Electrical and Electronics Engineers (IEEE)
70
Standards and Specifications Affecting Cables International Electrotechnical Commission (IEC) Insulated Cable Engineers Association (ICEA) Association of Edison Illuminating Companies (AEIC)
71
Codes Affecting Cables and Systems
National Electrical Code (NEC) National Electrical Safety Code (NESC)
72
24
Codes Affecting Cables and Systems
Code of Federal Regulations
Operating
requirements
73
American National Standards Institute (ANSI) Established in 1918 by 5 engineering societies and 3 government organizations Composed of volunteer member companies
74
ANSI Scope ANSI oversees the development of voluntary consensus standards for products, services, and processes in the United States. ANSI also coordinates U.S. standards with international standards so that American products can be used worldwide.
75
25
ANSI Scope (Cont)
Accreditation by ANSI signifies that the procedures used by the standards body in connection with the development of American National Standards meet the Institute’s essential requirements for openness, balance, consensus, and due process.
76
ANSI Standards for Cable ANSI/IEEE 386 – IEEE Standard for Separable Insulated Connector Systems for Power Distribution Systems above 600 V ANSI C119.4 – Standard for Electric Connectors
Connectors
Used Between Conductors
Aluminum-to-Aluminum or Aluminum-to-Copper
77
ASTM International (ASTM) Originally known as American Society for Testing and Materials Uses a Consensus Process
From
http://en.wikipedia.org/ Consensus Process – “A group decision making process that not only seeks the agreement of most participants, but also the resolution or mitigation of minority objections.” 78
26
ASTM Publication Types Standard Specification, that defines the requirements to be satisfied by the subject of the standard. Standard Test Method, that defines the way a test is performed. The result of the test may be used to assess compliance with a Specification.
79
ASTM Publication Types (Cont) Standard Practice, that defines a sequence of operations that, unlike a test, does not produce a result. Standard Guide, that provides an organized collection of information or series of options that does not recommend a specific course of action.
80
ASTM Standards for Cable ASTM B 230 – Standard Specification for Aluminum 1350-H19 Wire for Electrical Purposes ASTM B 8 – Standard Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft Others for plastic and other materials
81
27
Institute of Electrical and Electronic Engineers (IEEE) The IEEE is an international non-profit, professional organization for the advancement of technology related to electricity. It has the most members of any technical professional organization in the world, with more than 365,000 members in around 150 countries.
82
IEEE Background IEEE was formed in 1963 Power and Energy Society (PES) (Formerly Power Engineering Society) Main group of the IEEE PES that develops standards for cables and accessories is the Insulated Conductors Committee (ICC)
83
IEEE Standards and Guides (ICC)
Develops and Maintains Standards and Guides for Cables Systems and Accessories:
IEEE
Std 386 – Separable Connectors Std 404 – Cable Joints
IEEE Std 48 – Cable Terminations
IEEE Std 400 (and associated point documents) – Diagnostic Testing in the Field
Many others
IEEE
84
28
National Electrical Code (NEC) NEC 2008, NFPA 70 90.2 Scope (B) Not Covered – (5) “Installations under the exclusive control of an electric utility where such installations…
b.
Are located in legally established easements or rights-of-way designated by or recognized by public service commissions, utility commissions, or other regulatory agencies having jurisdiction for such installations....” 85
NEC (Cont)
The NEC does not have jurisdiction over utilities.
However, the NESC does have jurisdiction over utilities.
86
National Electrical Safety Code (NESC)
Work began on the NESC in 1913 at the National Bureau of Standards (NBS) As NBS Handbooks The 4th edition (1927) is shown here. ANSI gets approval by sending out to interested committees.
87
29
NESC (Cont)
IEEE C2 (IEEE is the secretariat) Recognized by ANSI Adopted as law by most states within the US as the binding code for electrical power systems. 88
NESC (Cont) “…Applicable to the systems operated by utilities, or similar systems and equipment of an industrial establishment or complex under the control of qualified persons.” NESC Abstract, 2007 Edition Part 3 – Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines
Section
Section
33 Supply Cable 35 Direct-buried Cable 89
International Electrotechnical Commission (IEC) The IEC is a not-for-profit, nongovernmental international standards organization that prepares and publishes international standards for all electrical, electronic, and related technologies Instrumental in developing the International System of Units (SI) (metric system)
90
30
IEC (Cont) ANSI is represented on the IEC through the US National Committee IEC Technical Committee 20 is responsible for Electric Cables
91
IEC Cable Standards IEC 60502 – Power cables with extruded insulation and their accessories for rated voltages from 1 kV up to 30 kV IEC 60840 – Power cables with extruded insulation and their accessories for rated voltages above 30 kV up to 150 kV - Test methods and requirements
92
IEC Cable Standards (Cont) IEC 62067 – Power cables with extruded insulation and their accessories for rated voltages above 150 kV up to 500 kV IEC 60287 – Calculation of the continuous current rating of cables IEC 60228 – Conductors of insulated cables
93
31
Insulated Cable Engineers Association (ICEA) The ICEA is an organization that develops standards for electric power, control, telecommunications, and portable cables Established in 1925 Not-For-Profit association Members are sponsored by about thirty North American cable manufacturers Works with cables only – not accessories.
94
ICEA Document Types
Publications or Guides
ICEA
P-32-382-2007 Short-Circuit Characteristics of Insulated Cable
Test Methods
ANSI/ICEA
T-31-610-2007 Test Method for Conducting a Longitudinal Water Penetration Resistance Test on Blocked Conductors
Standards
ANSI/ICEA
S-94-649-2004 Concentric Neutral Cables Rated 5 Through 46 kV 95
ICEA MV Cable Standards for Utilities ANSI/ICEA S-94-649-2004 Concentric Neutral Cables Rated 5 Through 46 kV ANSI/ICEA S-97-682-2007 Utility Shielded Power Cables Rated 5 Through 46 kV ANSI/ICEA S-108-720-2004 Extruded Insulation Power Cables Rated Above 46 Through 345 kV
96
32
Medium Voltage Cable Overview Manufacturing, Testing, Cable Prep and Installation Doble Tutorial, Boston
Background Joe Zimnoch Jr • Sr Applications Engineer- Okonite • 27 years – 8 Years in HV Lab – Remainder in Application Engineering
March 31, 2011
Cable Design - Components • • • • • •
Conductors -Purpose
Conductor Semiconducting Strand Screen Insulation Semiconducting Insulation Screen Metallic Shield Protective Covering – Jacket / Armor
•
In other words, why do we have different conductor sizes?
Conductor Terminology
Conductors •
• •
Conductivity 100% Copper 61% Aluminum 16.6% Steel 15% Tin 8% Lead 108% Silver Shapes – Class B Concentric – Compressed - Compact Other Classes C,D,H, …..
To provide a low resistance path for the flow of current such that the (1) cable’s temperature ratings are not exceeded (2) voltage regulation (drop) is within acceptable limits
What are MCM and kcmil ? • • • •
Answer: Thousands of circular mils M and k: M = Roman Numeral; MKS abbreviation for thousand 1 mil = 0.001” (¼” = 0.25” = 250 mils; 1” = 1000 mils) CM and cmil = circular mil (area of a circle w/o )ח
•
If Area (sq in.) = חr2
• Then 1 circular mil = D2 (diameter of wire in mils squared) • Example Thus for a solid #10 awg wire – Diameter = 0.1019” or 101.9 mils – CM area = (101.9)2 = 10,380 circular mils AWG- American Wire Gauge
CMA Calculation for 500 MCM Conductor For a 500 mcm (class B – 37 x 0.1162”) Diameter of = 0.1162” or 116.2 mils area of 1X = (116.2 mils)2 = 13,502 circular mils (13,502 circular mils) x (37) = ~500,000 circular mils 500,000 circular mils = 500 mcm (or kcmil) For a 500 mcm (class I – 1225 x 0.0201”) Diameter of = 0.0201” or 20.1 mils area of 1X = (20.1 mils)2 = 404 circular mils
Conductors - Classes 500 mcm Class B – 37 wires (116.2 mils/wire) Class C – 61 wires (90.5 mils/wire) Class H – 427 wires (34.2 mils/wire) Class I – 1225 wires (20.1 mils/wire)
(404 circular mils) x (1225) = ~500,000 circular mils 500,000 circular mils = 500 mcm (or kcmil)
EHB Excerpt, P. 1, Table 1.1 Conductor Size #1
Circular Mil Area (circular mils) 83,690
1/0
105,600
4/0
211,600
250 mcm
250,000
500 mcm
500,000
Conductors: Stranding – Class B
Conductors – Class B
1 1+6=7 1 + 6 + 12 = 19 1x, 7x, 19x, 37x, 61x, 91x, 127x, etc…
Class B Conductor Stranding Types All three have the SAME cross sectional area i.e. all are 500 kcmil.
7 wires
19 wires
37 wires
#24-#2
#1 – 4/0
250-500 mcm
61 wires 750-1000 mcm 500 mcm (37 strand) Diameters Differences 0.813” 0.788” (-3%)
0.736” (-10%)
Class B Conductor Stranding Types All three have the SAME cross sectional area i.e. all are 500 kcmil. The main difference is that the concentric has a large amount of space between the individual strands that is not accounted for in the cross section area calculation. Conversely the compact round conductor has very little trapped area between the strand Trapped air
Compressed, Compact & Flex
NO Trapped air
Cross sectional area of each conductor 500 kcmil 500 kcmil 500 kcmil
Rope Strand • • • • • • •
350 kcmil 37 Ropes 24 wires/rope 37x34=888 wires total 1 wire OD=20 mils 202= 400 cm/wire 400 x 888=355 kcmil
500 mcm connector: •1 compressed conductor in one side •1 compact round conductor in the other side.
Flex
Compressed
Compact Round, C/R
Compact vs. Compressed in a Connector • When compressed into the same size connector, both the compact conductor AND compressed look almost identical since they both have the same cross sectional area (the area is based on the area of EACH individual strand times the number of strands. • The cross sectional area is NOT based on the overall diameter of the conductor.
They were then crimped using 500 mcm die and then cut across the crimps
Conductor A - crimped in 500 mcm connector
Conductor B - crimped in 500 mcm connector
Which is compact? A or B?
Which is compact? A or B?
A=Compact Conductor
400 mcm vs. 500 Connector
A=Compact Conductor (notice SQUARED strands on left side of picture)
B=Compressed Conductor (notice ROUNDED strands on left side of picture)
B=Compressed Conductor
500 mcm
400 mcm
Diff
Length
3.53”
3.00”
-0.53”
OD
1.06”
0.965
-0.095”
ID 0.841”
0.767”
-0.074”
Wall 0.110”
0.100”
-0.010
500 mcm c/r OD = 0.736”
Why? • Connectors are designed based on compression ratio. • The compression ratio is the area of the conductor (not counting the air gaps between the strands) and the area of the connector before and after the crimp. • The area of the conductor (again not counting the air gaps between the strands) is the same for both the compressed and compact conductor.
Connectors for Pre-Molded Accessories ( Elbows, Tee-Bodies, Splices, etc) • Shorter crimp length • Heavy wall of rubber
–Use connector/lug per manufacturers recommendation.
Wire Drawing - Mechanical forming by tension through a die.
TUNGSTAN CARBIDE DIE 5/16"ROD
SLIGHTLY SMALLER WIRE
PULL DIRECTION
American Wire Gauge (AWG) • In order to make a # 10 awg wire from a 5/16” Cu or Al rod, the rod must be drawn through - 10 die. • Likewise, a #24 awg must go through 24 die.
American Wire Gauge (AWG) • • • • •
Industry standard for electrical wire. Based on 40 sizes between #36 and 4/0. OD of a 4/0 = 0.46” (~ 0.50”) OD of a #36 = 0.0050” Using geometric progression, the ratio OD diameters is: OR
Therefore an increase in AWG size increases OD by 12.3%
The End Result • A #10 awg has: – – – –
OD = 0.10” Area = 10, 380 circular mils DC Resistance = 1 ohm/mft (copper) Weight = 10 π (or 31.4 lbs/mft)
• Increasing or decreasing 10 awg sizes changes the area, resistance and weight by a factor of 10. –#10 to #20 –10, 380 to 1,020 cm –0.999 to 10.1 ohms/mft –31.4 to 3.1 lbs/mft
Not • Not - Function: adverb Etymology: Middle English, alteration of nought, from nought, • 1 —used as a function word to make negative a group of words or a word • 2 —used as a function word to stand for the negative of a preceding group of words
5000 lbs coils (bales) of 5/16” copper rod in Paterson.
The Not’s You can determine the OD of 40 different sizes from a #36 up to a 4/0. Using: To determine the the OD of a #24, substitute 24 for n; likewise for a #1, n = 1. In order to determine the next larger size above #1 (remember there are 40 sizes) n = 0 (Or 1 zero aka 1/0). Now for a 2/0 substitute n = -1, for 3/0 n = -2 and for 4/0 n = -3. Calling the sizes -1,-2 and -3 does not play well, so they are are called 1/0, 2/0, etc..
AWG Trivia An increase of 1 AWG size → 12.3% OD increase → 26.1% Area increase
↑ # 2 to #1 (solid) → 257.6 mils * 1.123 = 289.3 → 66,360 cm * 1.261 = 83,680
An increase of 2 AWG sizes ↑ #14 to #12 (solid) → 64.1 mils * 1.261 = 80.8 → 26.1% OD increase → 4110 cm * 1.59 = 6,535 → 59 % Area increase An increase in 2 AWG sized yields ~60% weight increase. For example a #12 weighs 20.1 lbs/mft versus 12.66 for a #14. Romex, 250 ft - 14/2 w/g $55 Romex, 250 ft - 12/2 w/g $84
5000 lbs bales of 5/16” copper rod in Santa Maria, CA
5000 lbs coils (bales) of 1/4” aluminum rod in Santa Maris, C
5/16” copper rod being paid off.
Copper rod thru die. Larger OD on Left; smaller on Right.
Multiple die w/Copper rod.
Multiple die w/Copper rod in action. Oil and water mixture for cooling and lubrication
Empty shop reel (bobbin) being loaded w/drawn wire.
A #14 wires exits the drawing process at approx 4000 ft/minute.
Bobbins loaded w/drawn wire. Approx 600 lbs of wire per bobbin.
One wire fed into front of strander •6 wires spun around 1 •12 wires spun around 7 •etc..
Bobbin loaded onto head.
One wire fed into front of strander.
Wires being spun around center wire(s).
Close up of 6 wires being spun around center wire at closing die.
Close up of 18 wires being spun around center 19 wires.
Corona or Partial Discharge In Air A partial arc or discharge to moisture, dust, or grounded areas. In a Cable Discharge that can occur off the conductor (sharp points), between layers, at a void or contaminate and at the shield. Finished conductor now ready to be insulated.
Corona Likes Sharp Points 800 kV AC Transformer Connected to 230 kV Pipe Cable in 500 kV Lab Potheads.
Corona discharge off sharp points at 500 kV-AC. Used to draw voltage upwards away from grounded base of pothead.
Insulation and Screens
Conductor Screen
EPR or XLPE Insulation Insulation Screen
Conductor, Conductor Screen, Insulation, Insulation Screen, Shield/Neutral, Jacket
Equal Terms
Discharge-Free vs. Discharge Resistant Discharge-Free
Discharge Resistant
Okonite
Company X
Company A Company B
Vulcanizing Curing Cross-linking (XL)
Company C Company D Company J
All are equal terms:
Company F Company G Company H
to convert a rubber or plastic compound into a
Company M Company J
“Thermoset” state
Thermoplastic • Can be melted back to liquid • Fair deformation resistance (memory) • Limited temperature rating (75C) Thermoset • Cannot be melted back to liquid • Excellent deformation resistance (memory) • Higher temperature rating (90C to 105C)
Over Cooked Spaghetti Analogy
Thermoplastic Melts back to its original liquid form
Thermoset burns but never reverts back to its original liquid form
Thermoset • Ethylene Propylene Rubber (EPR) • Crosslinked Polyethylene (XLPE) • Tree Retardant Crosslinked Polyethylene (TR-XLPE) Thermoplastic • Polyethylene (PE) • Polyvinyl Chloride (PVC) • PVC/Nylon
Insulation – Thicknesses Voltage Rating
Insulation – Typical Materials
Insulation – Thicknesses
100 %
133%
5 kV (shielded) 15 kV
90 mils
115 mils
175 mils
220 mils
25 kV
260 mils
345 mils
35 kV
345 mils
420 mils
0.001”= 1 mil, alternately 1 inch = 1000 mils
100 %
133 %
Relay Clears Relay Clears < 1min. < 1hour For 3 phase systems
For 3 phase systems
173%
Indefinite
For delta systems where one phase may be indefinitely grounded.
133% and 173% Insul Level Protects Un-faulted Cables when One Fails • When one cable fails, the voltage on the two un-faulted cables may increase from 133 to 173% of the phase-to-ground voltage. • Depends if Wye or Delta and how balanced the loads are.
Fault
Extrusion • Deformation process. • Shaping by pushing material through a die. CYLINDER DIE
RAM
EXTRUDED ROD, BAR, ANGLE, ETC..
LIQUID METAL, RUBBER, ETC..
Four Types of CV Tubes
ORANGEBURG MANUFACTURING
CV Equipment
CV Curing Tube
• CV Extrusion equipment located in peak of roof • CV curing tube runs length of building
Continuous Vulcanization (CV) Extrusion
• CV Extrusion equipment located in peak of roof
CV Curing Tube Curved
CV Curing Tube Support Beam Straight
• CV curing tube runs length of building
• Finished Cable Core: • • • •
Conductor Conductor Screen Insulation Insulation Screen
CV Curing Tube Curved to Accommodate Catenary Shape of Cable
Why is a Shield Needed? • Controls stresses within the insulation – Permits thinner insulation • Confines field within shield – No potential on surface of cable • Controls discharge to ground • Above 2000 volts is when the above becomes apparent.
Greater than 2000 VOLTS
5 kV NS at 4160 volts
Discharge from phase-to-phase
The 2005 NEC reduced rating from 5 to 2.4 kV for NS Also completely eliminated 8 kV NS cables
5 kV NS at 4160 volts Discharge from phase-tophase and phase-toground
Shielding • • • • • • • • •
Confines the electrical field within the insulation. Reduces the chance of electrical shock Provides a symmetrical distribution of stress Prevents surface discharge Reduces electrical interference Monitor voltage Provides a path for fault currents Can be used as a neutral Can affect ampacity rating (circulating current)
Effect of Fault Current in Shield on Jacket
Factors to Consider for Shield Design • • • •
Fault current capability Use as neutral (single phase or 3 phase) Shield voltage (single point grounding) Shield circulating current (multi-point grdg) and its effect on ampacity • Flexibility and minimum bending radius • Ease of making ground connections
• • • •
Fault current returning to ground on the shield will produce higher than normal heat. Excessive heat can melt the overlying jacket. A lower the resistance shield, produces less heat. Adding more copper (wires, tape, armor) lowers the shield resistance.
Copper Tape Shield
Copper Tape and Wires
Flat Copper Straps (PILC Replacement Cable)
Wire Shield or Concentric Neutral
Longitudinally Copper Shield (LCS)
Lead Sheath
Shield Fault Current Capability Shield Design
Circular Mil Area (CM)
Fault Capability -10 cycles (kA)
5 Cu Tape, 12.5% lap
18,974
3.22
5 Cu Tape, 25% lap
20,494
3.48
5 Cu Tape, 50% lap
25,100
4.26
5 Cu LCS, ¼” overlap
31,000
5.26
6 x 20 x 175 Cu Straps
26,738
4.54
16 x 35 x 200 CS (90% Coverage)
32,870
5.58
11 x #14 wires (1/3rd N for 2/0 Cu)
45,197
7.67
18 x #14 wires (1/3rd N for 350 Al)
73,959
12.55
5 Cu Tape, 12.5% lap/Al Armor
103,423
17.55
0.095” Lead Sheath
511,100
86.74
1.25” core OD, thermoplastic jacket (constant=0.288) Per Okonite EHB, Page 15
Single Conductor w/Armor
Shielding – Types, Listed from High Resistance to Low • Flat copper tape (High Resistance) • Longitudinally corrugated tape (LCS) copper or bronze tape • Concentric Cu wires & Flat Straps • 1/C Al. Armor-CLX • Lead sheath (Low Resistance)
GRAPHIC OF SINGLE POINT GROUND Leakage I thru Insul is shunted to grd via shield. Current thru shield resistance produces voltage. MAGNETIC FIELD
SHIELD
CONDUCTOR
CURRENT FLOW
SHIELD VOLTS 25 to 100 V
DISTANCE
a.k.a – open circuited shield
Shielding Resistance dictates amt of circulating current
GRAPHIC OF MULTI-POINT GROUND
TRANSFORMER EFFECT OF MULTI-POINT GROUND
SHIELD
CONDUCTOR
CONDUCTOR
SHIELD
SHIELD VOLTS
CONDUCTOR
SHIELD
0V DISTANCE
a.k.a – short circuited shield
a.k.a – short circuited shield
Shield Circulating Current
Concentric Neutral (Shield)
• When multi-point grounded acts like a transformer. • The lower the shield R, the closer we approach 1:1. • If the shield R is ½ of the conductor resistance, theoretically as much as 50% of the load current may circulate on the shield.
• •
Acts as both a neutral and a shield. Concentric wires return phase current – Full neutral for single phase (2/C Cable) – 1/3rd neutral for three phase
Scenario D (grounded at ONE point)
Concentric Neutral (Shield) • •
Acts as both a neutral and a shield. Concentric wires return phase current – Full neutral for single phase (2/C Cable) – 1/3rd neutral for three phase (return current 120° out of phase). SINGLE PHASE 1/0 ALUM
1-1/C 500 kcmil Cu, 220 Okoguard, 1/3rd Neutral Cables per 3” duct, 3 ducts 7.5” on center
Ampacity = 583 amps Losses = 29.16 watts/ft total
Scenario E (grounded multiple points) 1-1/C 500 kcmil Cu, 220 Okoguard, 1/3rd Neutral Cables per 3” duct, 3 ducts 7.5” OC,
Ampacity = 424 amps Losses = 31.19 watts/ft total
THREE PHASE 4/0 ALUM
ANY VOLTAGE
ANY VOLTAGE
1/0 AWG AL
Ampacity Comparison Single Point vs. Multi-point Grounding
1/0 AWG AL 4/0
16 x #14 WIRES EQUAL TO 1/0 AL
11 x #14 WIRES - EQUAL TO 1/3RD OF A 4/0 AL
Scenario A (3-1/C’s per Duct)
Comparison Triangular & Flat Spaced Configuration
3-1/C 500 kcmil Cu, 220 Okoguard, 1/3rd Neutral Cables
Ampacity = 449 amps Losses = 25.47 watts/ft total
Scenario E (1/C per Duct) 1-1/C 500 kcmil Cu, 220 Okoguard, 1/3rd Neutral Cables per 3” duct, 3 ducts 7.5” OC
Ampacity = 424 amps Losses = 31.19 watts/ft total
Ampacity Comparison 1/C per Duct vs. 3-1/C’s per Duct (Both Multi-point grounded)
Source : NRECA
15 kV, Aluminum Condr, URD, Direct Buried, 1 Ckt, Conductor Triangular Config Flat Spcd Config Size 75% LF 100% LF 75% LF 100% LF 1/0 (1/3)
207
187
231
206
4/0 (1/3)
308
276
340
301
350 (1/3)
405
362
430
376
500 (1/3)
488
432
499
431
750 (1/3)
593
521
578
494
1000 (1/6)
698
609
666
570
Soil=90 RHO, 90C Condr, 25C Soil Use Flat Spacing for Small Conductor Installations
Shield/Neutral Summary • Controls voltage stress in the insulation. • Some shields can also be used as a neutral. • Multi-point grounding recommended to reduce shield voltage and for safety. • Shield must also be designed to carry the available phase-to-ground fault current • The more copper in the shield, the greater the circulating current depending on the physical arrangement and load current.
Jackets • Cable Jacket – Nonmetallic Outer Covering of a Cable • Two Broad Categories: Thermoset and Thermoplastic • For each application, the operating temperature and environment must be considered
Types of Cable Jackets
Jacket – Desired Characteristics • • • • • • •
PHYSICAL CHEMICAL TEMPERATURE MOISTURE AGING FLAME SMOKE
Thermoplastic – PE (Polyethylene HD, MD, LD, LLD) – PP (Polypropylene aka living hinge) – PVC (Polyvinyl Chloride) – TP-CPE (Thermoplastic-Chlorinated Polyethylene) – TPPO (Thermoplastic Polyolefin - low smoke zero halogentransit industry) Thermoset – Neoprene (PCP - Polychhloroprene) – Hypalon (CSPE – Chlorosulfonated Polyethylene) (discontinued) – TS-CPE (Thermoset-Chlorinated Polyethylene) – XLPO (Cross Linked Polyolefin - low smoke zero halogentransit industry)
Factory Tests
Factory Electrical Tests • • • • •
DC Conductor Resistance Insulation Resistance (Megger) Shield Continuity Corona (4 times operating; K1
1
Tan
2
Tan
1
=
K2 K1
22 © 3M 2008. All Rights Reserved.
Hi-K Stress Control
23 © 3M 2008. All Rights Reserved.
80%
80%
24 © 3M 2008. All Rights Reserved.
8
Void Filling at Semicon Step Important for partial discharge values With right void filling material can greatly reduce surface stress on termination Hi K mastic and tube both refract the stress, but both are also electrical insulation Stress control tube 25
Stress control mastic © 3M 2008. All Rights Reserved.
II. External Leakage Insulation between H.V. Conductor and Ground (Tracking Protection) TRACKING: The irreversible degradation of surface material due to formation of conductive carbonized paths SURFACE TRACKING: The progressive formulation of conducting Carbon Paths from decomposition of electrical insulation and Organic Contaminants caused by Electrical Surface Discharges. 26 © 3M 2008. All Rights Reserved.
Tracking Three conditions must exist in order for tracking to take place: • CONTAMINATION
• MOISTURE
- Dust
- Humidity
- Chemicals - Salt - Other Airborne Particles
-
• VOLTAGE
Fog Condensation Mist Snow Rain
- Surface Stress (V/mil) 27 © 3M 2008. All Rights Reserved.
9
Factors In Surface Degradation (Loss in Surface Resistivity) Sunshine
Dew, or Light Rain
Frost
UV Cosmic Rays Surface Degradation
Rapid Changes In Temperature Differential Thermal Expansion
Temperature Rise: Chemical Degradation Acceleated Increased
Rapid Changes In Temperature Differential Thermal Expansion
Crazing and Cracking Greater Absorption of Contamination
Chemical Degradation
Surface Contamination Hydophobicity Affected
Dust
Carbon Particles
Abrasion Electric Stress
Soluble Matter SO 2, NH3, NO 2 Salt Spray Surfacing Conduction Heating & Evaporation Dry Band Formation
Electron & Ion Bombardment
Erosion Surface Wets Hydrofillic
Heavy Rain May Clean Surfaces
Fog
High Relative Humidity May Reduce Flashover Voltage Across Insulators Surface Wets
Stress Concentration Surface Discharges Hydrofillic
Flashover
Chemical Degradation To Carbon
TRACKING
28 © 3M 2008. All Rights Reserved.
Methods of Protecting Against Tracking Damage 1. Increase Distance from HV to Ground 2. Rain Shed (Insulator Skirts) 3. Track Resistant Materials ¾ Porcelain ¾ Inorganic Fillers in Rubber ¾ Inorganic Fillers in EVA (Heat Shrink) ¾ Silicone Rubber 4. Use Hydrophobic Materials 29 © 3M 2008. All Rights Reserved.
30 © 3M 2008. All Rights Reserved.
10
Silicone is Hydrophobic
31 © 3M 2008. All Rights Reserved.
Water Also Beads-Up on Silicone When Aged & Contaminated
Coated with ASTM D-2132 Contaminant
32 © 3M 2008. All Rights Reserved.
Material Benefits – Silicone Rubber 1.
Silicone is Hydrophobic. Inherently Track-resistant.
2.
Silicone can recover its Hydrophobicity.
3.
Silicone is inherently UV-Stable.
4.
Silicone is mostly Inorganic – No conducting carbon path.
5.
Silicone has a smooth surface.
33 © 3M 2008. All Rights Reserved.
11
III. A Seal to the External Environment Must seal at the top and the bottom of the termination IEEE-48 standard new requirement for sealing Termination placed underwater and current cycled on for 8 hours and off for 16 hours each cycle for ten cycles. Then termination removed from water and electrically tested with partial discharge and AC withstand test
34 © 3M 2008. All Rights Reserved.
External Environmental Seal QT-II Silicone Tape Seal
QT-III Top Seal Mastic
35 © 3M 2008. All Rights Reserved.
Benefits of Cold Shrink • No tools needed for installation • Low installation force • Good interfacial pressure • Live seal • Broad application range • Environmentally stable materials
36 © 3M 2008. All Rights Reserved.
12
Factors Affecting Termination Performance As seen, many things can affect the performance of terminations We try to balance those issues to provide a high performing long life termination
37 © 3M 2008. All Rights Reserved.
Splice Theory Splice design is totally different than termination design A splice moves the stress from cable to splice and back to cable instead of trying to control the stress as it enters the air A splice basically rebuilds the cable layers Considerations for the three main areas of a splice – electrode, insulation, and semi-con
38 © 3M 2008. All Rights Reserved.
Splicing A splice can be defined as two or more conductors joined with a suitable connector and reinsulated, reshielded, and rejacketed with compatible materials applied to a properly prepared surface.
Or simply, Rebuilding the cable!
39 © 3M 2008. All Rights Reserved.
13
SHIELDED POWER CABLE COMPONENTS 1. Conductor 2. Strand Shield 3. Insulation Insulation Shield 4. Semi-conducting Layer 5. Metallic Shield 6. Jacket
40 © 3M 2008. All Rights Reserved.
Connector -- Connector Shield (Electrode) Forms a faraday cage around the connector and portions of the cable beyond the connector. • Eliminates Dielectric Stresses in Region Around Connector • Provides Favorable Geometry for Electric Field Control Around Connector
41 © 3M 2008. All Rights Reserved.
42 © 3M 2008. All Rights Reserved.
14
Insulation z
z
Provides dielectric integrity in areas of intense electric stress associated with the disruption and compression of the electric field. Ê Good dielectric insulating properties Ê Good thermal conductivity properties Provides and maintains the integrity of all interfaces 4 Bonded internal interfaces 4 Cable insulation interface 4 Additional internal splice interfaces -- Adapters -- Multiple layers Ê Excellent long-term physical properties
43 © 3M 2008. All Rights Reserved.
Electrical Stress Design Criteria • The maximum stress in the splice should be no greater than the maximum stress in the cable • The maximum interfacial stress should be no greater than half the maximum stress over the connector shield • The maximum stress over the connector shield should be approximately equal to two-thirds the maximum cable stress
44 © 3M 2008. All Rights Reserved.
Geometric Splice Field Plot
Special Electrode Design - Minimizes electrical stress - Undercut electrode end - places higher stresses within 45 splice insulation, not along cable interface © 3M 2008. All Rights Reserved.
15
Molded Rubber Splice Interface Length • Too Long - Excessive Splice Length - High Installation Force - Increased Factory Cost • Too Short - Unacceptable Stress - Low Reliability 46 © 3M 2008. All Rights Reserved.
25 kV Splice Interfacial Stress
47 © 3M 2008. All Rights Reserved.
Insulation Insulation thickness should be such that there will be an average of about 30 to 40 volts/mil electrical stress through the insulation This will vary some with the dielectric constant of the material and the cleanliness of the material
48 © 3M 2008. All Rights Reserved.
16
QSIII-5418 Connector Temperature Profile 132 130 128 126 124 122 120 118 116
Conductor 61
49
53
57
37
41
45
25
29
33
13
17
21
1
5
112
9
114
Conductor
Peak reading/day 61 days
Conductor Connector Connector
49 © 3M 2008. All Rights Reserved.
Shield • Maintains continuity of the cable shielding system ª Electric field containment ª Safety • Provides geometry for electric field control • Ensures adequate ground path for fault protection • Provides critical environmental seals for the splice-cable interface 50 © 3M 2008. All Rights Reserved.
Components of QS-III Cold Shrink Splice
51 © 3M 2008. All Rights Reserved.
17
Why Cold Shrink for a medium voltage splice? Constant pressure on cables/connector Studies have shown that higher interface pressure provides better electrical performance Good seal between cable and splice Lower interfacial electrical stress Higher impulse Voltage levels 3M invented Cold Shrink 40+ years ago
52 © 3M 2008. All Rights Reserved.
Why silicone rubber for a medium voltage Cold Shrink splice? Long Term Elasticity Properties - for Good Cold Shrink Performance Stability of Electrical Properties - for Maintaining Properties From Stretched Storage to Final Installation Flexible Splice Body – moves with cable, even at low temperatures (installed at -35° C) High Temperature Rating - Class “H” (180º C)
53 © 3M 2008. All Rights Reserved.
More Real-World Things to Consider Length of the Electrode
Connector growth
Crimping tools
Length of the Insulation Interface
Manufacturing tolerances
Length of the Semi-conductive End-Seals
Bend in cable
Cable prep dimensions
54 © 3M 2008. All Rights Reserved.
18
Separable Connectors (Elbows and Tee Bodies)
•Separable connectors are molded similar to premolded splices •Electrode, Shell, Insulation 55 © 3M 2008. All Rights Reserved.
History of Medium Voltage Accessories
First were tape joints and terminations over 50 years ago Pre-molded push on joints developed in early 1970’s First cold shrink patent issued in 1970 First cold shrink termination in 1976 Cold shrink joint first released in 1993 Totally integrated termination released in 1996 QSIII splices released in 1997
56 © 3M 2008. All Rights Reserved.
Common Elements Critical Issues
Preparation of the cable
Conductor connections
Protection from the environment
Stress Control
Premolded splices and some cold shrink use geometric stress control. Heat shrink splices and some cold shrink ones use high dielectric stress control
57 © 3M 2008. All Rights Reserved.
19
Workmanship Good cable preparation is the key to all accessories performing properly Dimensional tolerances are typically plus or minus 0.25” for most accessories. Uniformity of shrinking is critical for electrical performance. Poor practices still persist even after many initiatives 58 © 3M 2008. All Rights Reserved.
Electrical Tests on Accessories Terminations – IEEE-48
Tee bodies – IEEE-386
Splices – IEEE-404
Connectors – ANSI C119.4
Factory tests are required
premolded splices, elbows and tee bodies
Factory tests are NOT required
tape splices, heat shrink splices, terminations are any field assembled accessories.
Factory tests
Partial Discharge
1 min AC withstand.
59
© 3M 2008. All Rights Reserved.
CABLE PREPARATION Medium Voltage Shielded Power Cables Dimension A
Tape Marker Clean
X
Cable Semi-con
Metallic Shield
Cable Jacket
Conductor O.D.
Primary Insulation
60 © 3M 2008. All Rights Reserved.
20
61 © 3M 2008. All Rights Reserved.
62 © 3M 2008. All Rights Reserved.
63
Electrical Markets Division
© 3M 2008. All Rights Reserved.
21
64 © 3M 2008. All Rights Reserved.
65 © 3M 2008. All Rights Reserved.
SPLICING & TERMINATING “What Cable Info Do I Need?”
? • • • • •
Voltage Class (and insulation level)? _____________ Conductor Size (and Copper or Aluminum)? ________________ Cable Type (type of shield, armor, 3/C, etc.)?_______ Location (indoor, outdoor, manhole, pole, etc.)? ____ Other? ______________________________________
66 © 3M 2008. All Rights Reserved.
22
Thank you for your time! Questions???
67 © 3M 2008. All Rights Reserved.
3M is a trademark of 3M Company. Important Notice Before using this product, you must evaluate it and determine if it is suitable for your intended application. You assume all risks and liability associated with such use.
Warranty; Limited Remedy; Limited Liability. 3M’s product warranty is stated in its Product Literature available upon request. All items made by others and specified by such brand which are included in any of 3M’s products or enclosed in a 3M package are warranted only to the extent specifically stated by the manufacturer of such item(s). 3M MAKES NO OTHER WARRANTIES INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. If this product is defective within the warranty period stated above, your exclusive remedy shall be, at 3M’s option, to replace or repair the 3M product or refund the purchase price of the 3M product. Except where prohibited by law, 3M will not be liable for any indirect, special, incidental or consequential loss or damage arising from this 3M product, regardless of the legal theory asserted.
68 © 3M 2008. All Rights Reserved.
3M Company
3M Electrical Markets Division 6801 River Place Blvd. Austin, TX 78726-9000 www.3m.com/electrical
69 © 3M 2008. All Rights Reserved.
23
View more...
Comments
