1、NEMA Standards PublicationNational Electrical Manufacturers AssociationANSI/NEMA WC 74-20125-46kV Shielded Power Cable for Use in the Transmission and Distribution of Electric EnergyApproved as an American National Standard ANSI Approval Date: December 18, 2012 Insulated Cable Engineers Association,
2、 Inc. Publication No. ICEA S-93-639 NEMA Standards Publication No. WC 74-2012 5-46kV Shielded Power Cable for Use in the Transmission and Distributionof Electric Energy Prepared and Sponsored by: Insulated Cable Engineers Association, Inc. P.O. Box 1568 Carrollton, Georgia 30112 Published by: Natio
3、nal Electrical Manufacturers Association 1300 North 17th Street Rosslyn, Virginia 22209 www.nema.org Copyright 2012 by the National Electrical Manufacturers Association and the Insulated Cable Engineers Association, Incorporated. All rights including translation into other languages, reserved under
4、the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions.ANSI/NEMA WC 74/ICEA S-93-639-2012 Page ii Copyright 2012 by National Electrical Manufacturers Association and the Insulated Cable
5、Engineers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unanimous agreement amo
6、ng every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) and the Insulated Cable Engineers Association (ICEA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary cons
7、ensus standards development process. This process brings together persons who have an interest in the topic covered by this publication. While NEMA and ICEA administers the process and establishes rules to promote fairness in the development of consensus, they do not independently test, evaluate, or
8、 verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA and ICEA disclaims liability for personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or co
9、mpensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA and ICEA disclaims and makes no guaranty or warranty, expressed or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no wa
10、rranty that the information in this document will fulfill any of your particular purposes or needs. NEMA and ICEA do not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this document a
11、vailable, NEMA and ICEA are not undertaking to render professional or other services for or on behalf of any person or entity, nor are NEMA and ICEA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judg
12、ment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additio
13、nal views or information not covered by this publication. NEMA and ICEA have no power, nor do they undertake to police or enforce compliance with the contents of this document. NEMA and ICEA do not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certi
14、fication or other statement of compliance with any health or safety-related information in this document shall not be attributable to NEMA and ICEA and is solely the responsibility of the certifier or maker of the statement. ANSI/NEMA WC 74/ICEA S-93-639-2012 Page iii Copyright 2012 by National Elec
15、trical Manufacturers Association and the Insulated Cable Engineers Association CONTENTS Page SECTION 1 GENERAL .1 1.1 SCOPE. 1 1.2 GENERAL INFORMATION 1 1.3 INFORMATION TO BE SUPPLIED BY PURCHASER. 1 1.3.1 Characteristics of System on Which Cable is to be Used 1 1.3.2 Quantities and Description of C
16、able 2 1.4 DEFINITIONS AND SYMBOLS. 2 SECTION 2 CONDUCTOR5 2.1 PHYSICAL AND ELECTRICAL PROPERTIES 5 2.1.1 Copper Conductors.5 2.1.2 Aluminum Conductors .5 2.2 OPTIONAL WATER BLOCKING COMPONENTS FOR STRANDED CONDUCTORS 6 2.3 CONDUCTOR SIZE UNITS 6 2.4 CONDUCTOR DC RESISTANCE PER UNIT LENGTH . 6 2.4.1
17、 Direct Measurement of dc Resistance6 2.4.2 Calculation of dc Resistance Per Unit Length6 2.5 CONDUCTOR DIAMETER 7 SECTION 3 CONDUCTOR SHIELD (STRESS CONTROL LAYER) . 13 3.1 MATERIAL .13 3.2 PHYSICAL REQUIREMENTS .13 3.3 ELECTRICAL REQUIREMENTS .13 3.3.1 Extruded Semiconducting Material 13 3.3.2 Ext
18、ruded Nonconducting Material (For EPR Insulation Only) . 13 3.3.2.1 Withstand Test. 13 3.3.3 Semiconducting Tape . 14 3.4 CROSSLINKED (THERMOSET) REQUIREMENTS 14 SECTION 4 INSULATION 15 4.1 MATERIAL .15 4.2 INSULATION THICKNESS .16 4.2.1 Selection of Proper Thickness 16 4.3 INSULATION REQUIREMENTS 1
19、6 SECTION 5 INSULATION SHIELDING 22 5.1 SHIELDING OF INSULATED CABLE22 5.1.1 Insulation Shield. 22 5.2 REMOVABILITY OF INSULATION SHIELD .23 5.2.1 Discharge-Free Cable Designs With Extruded Insulation Shields . 23 5.2.2 Discharge-Resistant Cable Designs With Extruded Insulation Shields 23 SECTION 6
20、METALLIC SHIELDING (SEE APPENDIX G) 26 6.1 GENERAL26 6.2 METAL TAPES .26 6.2.1 Helically Applied Tape(s) . 26 6.2.2 Longitudinally Applied Corrugated Tape. 26 6.3 COPPER WIRES, STRAPS, SHEATH OR ARMOR 26 6.4 MULTIPLE-CONDUCTOR CABLES .27 SECTION 7 COVERINGS 28 7.1 JACKETS.28 ANSI/NEMA WC 74/ICEA S-9
21、3-639-2012 Page iv Copyright 2012 by National Electrical Manufacturers Association and the Insulated Cable Engineers Association 7.1.1 Crosslinked and Thermoplastic Jackets - General . 28 7.1.2 Neoprene, Heavy-Duty Black (CR-HD) 28 7.1.3 Neoprene, General Purpose (CR-GP). 28 7.1.4 Polyvinyl Chloride
22、 . 28 7.1.5 Low and Linear Low Density Polyethylene (LDPE III can be used in either the “DISCHARGE-FREE” design or the “DISCHARGE-RESISTANT” design; IV is for use only in cables of the “DISCHARGE-RESISTANT“ design. All of the insulations are suitable for use on cables in wet or dry locations at volt
23、ages 5 through 46 kV between phases at the 100, 133 and 173 percent insulation level. The conductor temperature shall not exceed the following: Table 4-1 CONDUCTOR MAXIMUM RATED TEMPERATURES Insulation Material Normal Operation Emergency Overload* Short Circuit* XLPE, TRXLPE, and EPR Classes I, II &
24、 IV 90 C 130 C 250 C XLPE Class III, TRXLPE Class III & EPR Class III 105 C* 140 C 250 C * See Appendix B * Lower temperatures for normal operation may be required because of the type of material used in the cable joints and terminations or because of cable environmental conditions. Cable users shou
25、ld be aware that all of the jackets described in Section 7 are not necessarily suitable for cables having this maximum temperature rating. Consult cable manufacturer for further information. * Conductor fault current shall be determined in accordance with ICEA P-32-382. Other insulation materials co
26、mposed of Ethylene and Alkene units, which are designated as EAM, may be available and can meet the same physical and electrical requirements as the insulation materials described in this standard. See Appendix J and/or contact the manufacturer for further information. ANSI/NEMA WC 74/ICEA S-93-639-
27、2012 Page 16 Copyright 2012 by National Electrical Manufacturers Association and the Insulated Cable Engineers Association 4.2 INSULATION THICKNESS The insulation thicknesses given in Table 4-4 are based on the rated circuit voltage, phase-to-phase, conductor size and on the cable insulation level.
28、The minimum thickness and maximum thickness of the insulation shall be as specified in Table 4-4. (See 9.2.2 for method of measurement.) For identification, nominal thicknesses are shown in Section 8 Table 8-3. 4.2.1 Selection of Proper Thickness The thickness of insulation for various systems shall
29、 be determined as follows: 4.2.1.1 For Three-Phase Systems with 100, 133 or 173 Percent Insulation Level Use the thickness values given in the respective columns of Table 4-4. 4.2.1.2 For Delta Systems Where One Phase May Be Grounded For Periods Over One Hour Use the 173 percent thickness values giv
30、en in Table 4-4. Also, see the 173 percent level note following Table 4-4. 4.2.1.3 For Single- and Two-Phase Systems with 100 Percent Insulation Level Multiply the voltage to ground by 1.73 and use the resulting voltage value or next higher rating to select the corresponding insulation thickness in
31、the 100 percent insulation level column of Table 4-4 4.2.1.4 For Single- and Two-Phase Systems with 133 Percent Insulation Level Multiply the voltage to ground by 1.73 and use the resulting voltage value or next higher rating to select the corresponding insulation thickness in the 133 percent insula
32、tion level column of Table 4-4. 4.3 INSULATION REQUIREMENTS Insulations used in both DISCHARGE-FREE and DISCHARGE-RESISTANT cable designs are described in 4.3.1. 4.3.1 Physical and Aging Requirements When tested in accordance with Section 9, the insulation shall meet the requirements given in Table
33、4-2: ANSI/NEMA WC 74/ICEA S-93-639-2012 Page 17 Copyright 2012 by National Electrical Manufacturers Association and the Insulated Cable Engineers Association Table 4-2 INSULATION PHYSICAL REQUIREMENTS Physical Requirements Insulation Type XLPE and TRXLPE XLPE Class III and TRXLPE Class III EPR Class
34、 I II III IV Unaged Requirements Tensile Strength, Minimum Psi (MPa) 1800 (12.5) 700 (4.8) 1200 (8.2) 700 (4.8) 550 (3.8) Elongation at Rupture, Minimum Percent 250 250 Aging Requirements After Air Oven Aging for 168 hours Aging Temperature, C 1 C 121 136 121 136 121 Tensile Strength, Minimum Percen
35、tage of Unaged Value 75 75 80 75 Elongation, Minimum Percentage of Unaged Value Minimum Percent at Rupture 75 - 75 - 80 - 75 - - 175 Hot Creep Test at 150 C 2 C Unfilled Filled *Elongation, Maximum Percent 175 100 50 *Set, Maximum Percent 10 5 5 *For XLPE and TRXLPE insulations if this value is exce
36、eded, the Solvent Extraction Test (see 9.11) may be performed and will serve as a referee method to determine compliance (a maximum of 30 percent weight loss after 20 hours drying time). 4.3.2 Electrical Requirements 4.3.2.1 Partial-Discharge Extinction Level for Discharge-Free Designs Only. (See 9.
37、8.2) Each length of completed cable shall be subjected to a partial discharge test. For cables shielded with a nonmetallic semiconducting layer extruded directly over the insulation, the partial discharge shall not exceed 5 picocoulombs at the ac test voltage given in Table 4-4 or 4-4 (Metric). For
38、cables shielded with a semiconducting coating and a semiconducting tape, the partial discharge shall not exceed 5 picocoulombs at the ac test voltage given in Table 4-3: ANSI/NEMA WC 74/ICEA S-93-639-2012 Page 18 Copyright 2012 by National Electrical Manufacturers Association and the Insulated Cable
39、 Engineers Association Table 4-3 PARTIAL DISCHARGE REQUIREMENTS FOR SEMICONDUCTING COATING AND TAPE DESIGNS ONLY Rated Circuit Voltage, Phase to Phase, Volts Minimum Partial Discharge Extinction Level, kV 100% Insulation Level 133% Insulation Level 173% Insulation Level 2001-5000 4 5* 6 5001-8000 6
40、8 10 8001-15000 11 15 18 * Unless otherwise indicated, the cable will be rated at the 100% insulation level. 4.3.2.2 Discharge (Corona) Resistance for Discharge-Resistant Designs Only. (See 10.4) The insulation shall be verified as corona discharge resistant using a 21 kV 60 Hz voltage applied for 2
41、50 hours. No failure or surface erosion visible with 15 times magnification shall occur. Partial discharge measurements are not required for DISCHARGE-RESISTANT cables. 4.3.2.2.3 Voltage Tests (See 9.8.1) Each length of completed cable shall withstand, without failure, the ac test voltages given in
42、Table 4-4. The test voltage shall be based on the rated voltage of the cable and the size of the conductor. Factory dc testing is not required by this specification. However, a dc test may be performed with prior agreement between the manufacturer and the purchaser. Suggested dc test voltages are li
43、sted in Appendix D. 4.3.2.4 Accelerated Water Absorption Test, Electrical Method at 60 Hz (See 10.1.) When tested in accordance with T-27-581, the insulation shall meet the applicable requirements given in Table 10-1. 4.3.2.5 Insulation Resistance (See 10.2.) Each insulated conductor in the complete
44、d cable shall have an insulation resistance not less than that corresponding to a constant of 20,000 megohms-1000 feet at 15.6C. ANSI/NEMA WC 74/ICEA S-93-639-2012 Page 19 2012 by National Electrical Manufacturers Association and the Insulated Cable Engineers Association Table 4-4 CONDUCTOR SIZES, I
45、NSULATION THICKNESSES AND TEST VOLTAGES Rated Circuit Voltage, Phase-to-Phase Voltagea Conductor Size, (AWG or kcmil)b Insulation Thickness (mils) a-c Test Voltage, kVd 100 Percent Levelc 133 Percent Levelc 173 Percent Levelc 100 % Insulation Level 133 % Insulation Level 173 % Insulation Level Minim
46、um Maximum Minimum Maximum Minimum Maximum 2001-5000 8-1000e 85 120 85 120 135 170 18 18 28 1001-3000 135 170 135 170 135 170 28 28 28 5001-8000 6-1000 110 145 135 170 165 205 23 28 35 1001-3000 165 205 165 205 210 250 35 35 44 8001-15000 2-1000 165 205 210 250 245 290 35 44 52 1001-3000 210 250 210
47、 250 245 290 44 44 52 15001-25000 1-3000 245 290 305 350 400 450 52 64 84 25001-28000 1-3000 265 310 330 375 425 495 56 69 89 28001-35000 1/0-3000 330 375 400 460 550 630 69 84 116 35001-46000 4/0-3000 425 495 550 630 * * 89 116 150 ANSI/NEMA WC 74/ICEA S-93-639-2012 Page 20 Copyright 2012 by Nation
48、al Electrical Manufacturers Association and the Insulated Cable Engineers Association Table 4-4 (Metric) CONDUCTOR SIZES, INSULATION THICKNESSES AND TEST VOLTAGES Rated Circuit Voltage, Phase-to-Phase Voltagea Conductor Size, (mm2)b Insulation Thickness,(mm) a-c Test Voltage, kVd 100 Percent Levelc
49、133 Percent Levelc 173 Percent Levelc 100 % Insulation Level 133 % Insulation Level 173 % Insulation Level Minimum Maximum Minimum Maximum Minimum Maximum 2001-5000 8.37-506.7e 2.16 3.05 2.16 3.05 3.43 4.32 18 18 28 506.8-1520 3.43 4.32 3.43 4.32 3.43 4.32 28 28 28 5001-8000 13.3-506.7 2.79 3.68 3.43 4.32 4.19 5.21 23 28 35 506.8-1520 4.19 5.21 4.19 5.21 5.33 6.35 35 35 44 8001-15000 33.6-506.7 4.19 5.21 5.33 6.35 6.22 7.37 35 44 52 506.8-1520 5.33 6.35 5.33 6.35 6.22 7.37 44 44 52 15001-25000 42.4-1520 6.22 7.37 7.75 8.89 10
