ANSI NEMA WC 51-2009 Ampacities of Cables Installed in Cable Trays (JOINT PUBLICATION - NEMA WC 51 ICEA P-54-440).pdf

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1、NEMA Standards Publication National Electrical Manufacturers Association ANSI/NEMA WC 51-2009 (R2014) Ampacities of Cables Installed in Cable Trays 2014 National Electrical Manufacturers Association and the Insulated Cable Engineers Association, Inc. Approved as an American National Standard ANSI Ap

2、proval Date: September 18, 2014 ANSI/NEMA WC 51 ICEA P-54-440-2009 (R2014) Ampacities of Cables Installed in Cable Trays Prepared by: Insulated Cable Engineers Association, Inc. P.O. Box 1568 Carrollton, Georgia 30112 Published by: National Electrical Manufacturers Association 1300 North 17 thStreet

3、, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2016 National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International

4、 and Pan American Copyright Conventions. 2016 National Electrical Manufacturers 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. Con

5、sensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. The National Electrical Manufacturers Association (NEMA) and the Insulated Cable Engineers Association, Inc. (ICEA) standards and guideline publications, of which

6、the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together persons who have an interest in the topic covered by this publication. While NEMA and ICEA administer the process and establish rules to promote fairness in t

7、he development of consensus, they do not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in their standards and guideline publications. NEMA and ICEA disclaim liability for personal injury, property, or other damages

8、 of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA and ICEA disclaim and make no guaranty or warranty, expressed or implied, as to the accuracy or complet

9、eness of any information published herein, and disclaim and make no warranty 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 manufacturers or sellers products or services by vir

10、tue of this standard or guide. In publishing and making this document available, 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. An

11、yone using this document should rely on his or her own independent judgment 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 avail

12、able from other sources, which the user may wish to consult for additional 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 produ

13、cts, designs, or installations for safety or health purposes. Any certification 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. AN

14、SI/NEMA WC 51/ICEA P-54-440-2009 (R2014) Page i 2016 National Electrical Manufacturers Association Foreword This standards publication for Ampacities of Cables Installed in Cable Trays (ICEA P-54-440, NEMA WC 51-2014) was developed by the Insulated Cable Engineers Association, Inc. (ICEA) and approv

15、ed by the National Electrical Manufacturers Association (NEMA). It supersedes WC 51-2009. ICEA/NEMA standards are adopted in the public interest and are designed to eliminate misunderstanding between the manufacturer and the user and to assist the user in selecting and obtaining the proper product f

16、or his particular need. Existence of an ICEA/NEMA standard does not in any respect preclude the manufacture or use of products not conforming to the standard. The user of this standard is cautioned to observe any health or safety regulations and rules relative to the manufacture and use of cable mad

17、e in conformity with this Standard. Requests for interpretation of this Standard must be submitted in writing to: Insulated Cable Engineers Association, Inc., P.O. Box 1568, Carrollton, Georgia 30112 An official written interpretation will be provided. ICEA will welcome any suggestions on ways to i

18、mprove this standard. ANSI/NEMA WC 51/ICEA P-54-440-2009 (R2014) Page ii 2016 National Electrical Manufacturers Association ANSI/NEMA WC 51/ICEA P-54-440-2009 (R2014) Page iii 2016 National Electrical Manufacturers Association CONTENTS Page Foreword i Scope . iv History iv Section 1 GENERAL INFORMAT

19、ION 1 1.1 Background 1 1.2 References . 1 1.2.1 Normative References . 1 1.2.2 Other References 2 1.3 DEFINITIONS . 2 Section 2 TABLE DEVELOPMENT PARAMETERS . 4 2.1 Parameters Used to Develop Tray Ampacity Tables . 4 2.1.1 Cable Operating Temperatures . 4 2.1.2 Allowable Heat Generation 4 2.1.3 Calc

20、ulated Depth of Cables in Trays Apparent Fill Depth 5 2.1.4 Cable Diameters 5 2.1.5 Conductor Resistance . 5 2.1.6 Calculated Free-Air Ampacity 5 2.1.7 Ampacity Values 6 Section 3 AMPACITY ADJUSTMENT FACTORS . 7 3.1 Correction Factor for Diameters of Cables . 7 3.2 Correction Factor for Temperatures

21、 . 7 3.2.1 Ambient Temperature 7 3.2.2 Conductor Temperature 8 3.3 Correction Factor for Number of Conductors . 8 3.4 Correction Factors for Tray Covers 9 3.5 Correction Factors for Load Diversity . 9 3.5.1 Determining the Loading Factor 9 3.5.2 Diversity Factors 10 Section 4 EXAMPLES 11 4.1 Calcula

22、ting Apparent Depth of Cable . 11 4.2 Selecting Ampacity Values and Using Adjustment Factors . 12 4.3 Calculating and Applying Diversity Factors 13 4.4 Multiple Adjustment Factors . 13 4.5 Calculating Ampacities for Cables Not Covered by Tables 14 Section 5 TABLES 15 5.1 Index to Tables . 15 ANSI/NE

23、MA WC 51/ICEA P-54-440-2009 (R2014) Page iv 2016 National Electrical Manufacturers Association Scope This Standards Publication covers the ampacity ratings for 600-15,000 volt solid dielectric cables installed in cable trays. Ampacity ratings are tabulated for single conductor cables, triplexed asse

24、mblies of single conductor cables, and three-conductor cables incorporating an overall jacket. Ampacities have been tabulated for the cable constructions and the operating conditions normally encountered for tray applications. Correction factors to adjust the tabulated values to better reflect speci

25、fic conditions are provided. These include adjustments to account for ambient and operating temperatures, cable construction, tray covers, and diversification of the cable loading. This standard is intended primarily for use by the utility industry. It is not intended for use where compliance with t

26、he National Electrical Code or other regulations is mandatory. History Ampacity tables for cables in trays were published in the Insulated Power Cable Engineers Association Publication No. P-33-440, April 2, 1959 (IPCEA is currently known as ICEA). It assumed a load diversity but did not specificall

27、y define the diversity. The demands of modern generating plants required a more precise definition of operating conditions for the determination of cable ampacities. Experimental work with various cables and the loading of trays by J. Stolpe 1and the theory developed by Stolpe, Underwriters Laborato

28、ries Inc., Lee, 2and ICEA Publication P-46-426, IEEE S-135 Power Cable Ampacities, 1962 Edition provided a more accurate means of calculating ampacities of cables in trays. A joint committee of IPCEA and IEEE Insulated Conductors Committee utilized this work in preparing the ampacity tables. They we

29、re published in the IPCEA/NEMA Standards Publication for Ampacities of Cables in Open-top Cable Trays, IPCEA Publication No. P-54-440, NEMA Standards Publication No. WC 51-1972. They superseded the factors in Table B for cables without maintained spacing in the IPCEA “Factors for Calculating Ampacit

30、ies of Cables Installed in Ladder Supports, Trays and Troughs,” P-33- 440, April 2, 1959. Table A of that publication covering factors for cables with maintained spacing was not affected. The 1975 edition of the IPCEA/NEMA Standards Publication was expanded to cover 15 kV cables and includes a great

31、 many editorial corrections that clarify the 1972 document. The document was revised in April 1976 and again in August 1979. NEMA reaffirmed the document on November 20, 1980. In October 1984 a correction was made in the earlier Appendix D and was included in that edition. The members of IEEE-IPCEA

32、Joint Committee at the time of the initial writing were: R. C. Waldron, Chairman, D. A. Costello, E. Finch, E. L. Kolmorgen, M. J. Koulopoulos, R. H. Lee, R. A. Peterson, D. A. Silver, and J. Stolpe. The extended information contained in this revision was made possible through recent theoretical and

33、 experimental work by W. Z. Black and B. L. Harshe. 3, 4This edition has been expanded to include tray fill depths up to four inches and adjustment factors to account for tray covers and load diversity. In addition, the tables have been revised to reflect current cable design practices and conductor

34、 sizes through 2000 kcmil inclusive. _ 1 IEEE Transaction Paper 70 TP 557 PWR, Ampacity for Cables in Randomly Filled Trays, J. Stolpe, 19702 IEEE Transaction Paper 71 TP 543 PWR, Ampacity for Multiconductor Cables in Trays, R. Lee, 1971 3 IEEE Transactions on Power Delivery Vol. 9 No. 4, Oct. 1994,

35、 Ampacity of Cables in Single Open-Top Cable Trays, B. Harche & W. Black 4 IEEE Transactions on Power Delivery Vol. 12 No. 1, Jan. 1997, Ampacity of Cables in Single Covered Trays, B. Harche & W. Black ANSI/NEMA WC 51/ICEA P-54-440-2009 (2014) Page 1 2016 National Electrical Manufacturers Associatio

36、n Section 1 GENERAL INFORMATION 1.1 BACKGROUND Establishing the ampacity of cables installed in cable trays can become quite complex since a cable tray may contain hundreds of cables differing in size and loading. Methods to compute cable ratings under these operating conditions were developed first

37、 by J. Stolpe. This conservative technique assumes the cables are packed into the tray and are operating at maximum loading such that the heat generated can be assumed to be uniformly distributed throughout the total cable mass. This has been and continues to be the basis for the ampacity tables pro

38、vided in this standard. More recently, B. L. Harshe and W. Z. Black have developed models that account for load diversity and the presence of tray covers in the determination of allowable cable ampacity. The validation of their models also included tests using cable fill depths up to 4 inches. In re

39、cognition of this work, the tables have been expanded to include fill depths of 3.5 inches and 4 inches and adjustment factors have been added for diversity loading and the use of tray covers. Sample ampacity calculations are provided to demonstrate the use of the tables and adjustment factors. 1.2

40、REFERENCES The following publications are adopted in part, by reference in this standard, and are available from the organizations listed below. 1.2.1 Normative References The following normative documents contain provisions, which through reference in this text, constitute provisions of this Standa

41、rds publication. By reference herein, these publications are adopted in whole or in part as indicated, in this standard. ANSI/NEMA WC70/ICEA S-95-658-2009 Power Cables Rated 2000 Volts or Less for the Distribution of Electrical Energy ANSI/NEMA WC71/ICEA S-96-659-1999 Standard for Nonshielded Cables

42、 Rated 2001-5000 Volts for use in the Distribution of Electric Energy ANSI/NEMA WC74/ICEA S-93-639-2012 5-46 kV Shielded Power Cable for Use in the Transmission and Distribution of Electrical Energy ANSI/ICEA S-97-682-2013 Standard for Utility Shielded Power Cables Rated 5-46 kV ANSI/NEMA WC 51/ICEA

43、 P-54-440-2009 (R2014) Page 2 2016 National Electrical Manufacturers Association Institute of Electrical and Electronics Engineers (IEEE) 445 Hoes Lane Piscataway, NJ 08854 IEEE Standard 835-1994 IEEE Standard Power Cable Ampacity Tables International Electrotechnical Commission (IEC) 3, rue de Vare

44、mbre P.O. Box 131 CH - 1211 Geneva 20 - Switzerland IEC Publication 60287-1-1 (2001-11) Electric cables - Calculation of the current rating - Part 1- 1: Current rating equations (100 % load factor) and calculation of losses - General 1.2.2 Other References Institute of Electrical and Electronics Eng

45、ineers (IEEE) 445 Hoes Lane Piscataway, NJ 08854 IEEE Transaction Paper 70 TP 557 PWR, Ampacity for Cables in Randomly Filled Trays, J. Stolpe, 1970IEEE Transaction Paper 71 TP 543 PWR, Ampacity for Multiconductor Cables in Trays, R. Lee, 1971 IEEE Transactions on Power Delivery Vol. 9 No. 4, Oct. 1

46、994, Ampacity of Cables in Single Open-Top Cable Trays, B. Harche & W. Black IEEE Transactions on Power Delivery Vol. 12 No. 1, Jan. 1997, Ampacity of Cables in Single Covered Trays, B. Harche & W. Black http:/ 1.3 DEFINITIONS allowable heat generation: The maximum allowable heat generation (watts/i

47、nch 2 /ft) for the cable mass per unit length of tray. Exceeding this value will cause the cables in the tray to exceed their operating temperature limits. apparent fill depth: The calculated depth of cable in the tray. This value is used to determine the allowable heat generation for given tray fil

48、l conditions. The value is calculated by dividing the total area occupied by the cables in the tray by the width of the tray. To account for the fact that cables will not pack into a solid mass, each cable in the tray is assumed to occupy a space defined by a square whose sides equal the cable diame

49、ter. To determine the apparent fill depth (basis for calculations and tables) when given the % Tray Fill, the following equation must be used to account for the different methods used to determine the cross sectional area occupied by the cables (Refer to Section 4.1 for an example). Apparent Fill Depth = 4 % cover factor: The ampacity of a cable instal