ANSI NEMA C29 12-2013 Suspension Insulators

ANSI/NEMA C29.12-2013

American National Standard for Composite Insulators— Transmission Suspension Type

Secretariat:

National Electrical Manufacturers Association Approved: November 2013 Published: January 2014

American National Standards Institute, Inc.

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 among every person participating in the development of this document. American National Standards Institute (ANSI) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages 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 disclaims and makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or seller’s products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA 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 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 available from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, 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 is solely the responsibility of the certifier or maker of the statement.

AMERICAN NATIONAL STANDARD

Approval of an American National Standard requires verification by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. Caution Notice: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute.

Published by

National Electrical Manufacturers Association 1300 North 17th Street, Rosslyn, VA 22209  Copyright 2014 by National Electrical Manufacturers Association All rights reserved 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 and Pan American Copyright Conventions. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.

Printed in the United States of America.



C29.12-2013 Page i

FOREWORD (This Foreword is not part of American National Standard C29.12-2013.) This first edition of this standard was based on a NEMA proposed standards publication for composite suspension insulators used on overhead transmission lines. It was developed at the request of American National Standards Committee on Insulators for Electric Power Lines, ASC C-29. Suggestions for improvement of this standard will be welcome. They should be sent by the date of its next st scheduled revision which is December 31 , 2015 to: Senior Technical Director, Operations National Electrical Manufacturers Association th 1300 North 17 Street, Suite 900 Rosslyn, VA 22209 This standard was processed and approved for submittal to ANSI by Accredited Standards Committee on Insulators for Electric Power Lines, C29. Committee approval of the standard does not necessarily imply that all committee members voted for approval. At the time it approved this standard, the ASC C-29 Committee had the following members: Rob Christman, Chairman Steve Griffith, Secretary Organization Represented:

Name of Representative:

Edison Electric Institute

B. Freimark R. Christman E. Cleckley M. Garrels R. Kluge J. Varner (alt) G. Obenchain (alt)

Institute of Electrical and Electronic Engineers

T. Grisham J. Hildreth A. Jagtiani J. Kuffel E. Gnandt (alt)

National Electrical Manufacturers Association

P. Maloney A. Baker R. A. Bernstorf G. Powell G. A. Stewart E. Kress (alt) Z. Lodi (alt) E. Niedospial (alt) A. Schwalm (alt)

Tennessee Valley Authority

J. Nelson R. Stargel (alt)

Western Area Power Administration

R. Clark

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page ii



© 2014 National Electrical Manufacturers Association

C29.12-2013 Page iii

TABLE OF CONTENTS Page FOREWORD ........................................................................................................... ………………..iv 1

SCOPE ............................................................................................................................................ 1

2 2.1 2.2

NORMATIVE REFERENCES .......................................................................................................... 1 Referenced American National Standards ...................................................................................... 1 Other Standards .............................................................................................................................. 1

3 3.1 3.2

DEFINITIONS AND ABBREVIATIONS ........................................................................................... 1 Specified Mechanical Load (SML) ................................................................................................... 1 Routine Test Load (RTL) ................................................................................................................. 1

4

GENERAL ........................................................................................................................................ 2

5 5.1 5.2 5.3

MATERIALS .................................................................................................................................... 2 Core ........................................................................................................................................... 2 Weathersheds ................................................................................................................................. 2 Metal Parts ...................................................................................................................................... 2

6

DIMENSIONS AND CHARACTERISTICS ...................................................................................... 2

7

MARKING ........................................................................................................................................ 2

8 8.1 8.2 8.3 8.4 8.4.1 8.4.2 8.5

PROTOTYPE TESTS ...................................................................................................................... 3 Tests on Interfaces and Connection of End Fittings ....................................................................... 3 Core Time-load Test ....................................................................................................................... 3 Housing Tracking and Erosion Tests ............................................................................................... 4 Core Material Tests .......................................................................................................................... 4 Dye Penetration Evaluation ............................................................................................................ 4 Water Diffusion Test Evaluation ....................................................................................................... 4 Flammability test. ........................................................................................................................... 4

9 9.1 9.2 9.3 9.4

DESIGN TESTS ............................................................................................................................... 4 Low-Frequency Dry Flashover Test. ................................................................................................ 4 Low-Frequency Wet Flashover Test ................................................................................................ 4 Critical Impulse Flashover Tests - Positive and Negative ................................................................ 4 Radio-Influence Voltage ................................................................................................................... 5

10 10.1 10.2 10.3

QUALITY CONFORMANCE TESTS ............................................................................................... 5 Dimensional Tests............................................................................................................................ 5 Galvanizing Test............................................................................................................................... 5 Specified Mechanical Load Test ...................................................................................................... 5

11 11.1 11.2

ROUTINE TESTS ............................................................................................................................ 5 Tension-Proof Test........................................................................................................................... 5 Visual Examination ........................................................................................................................... 5

FIGURES 1 Oval-Eye End Fitting and Y-Clevis End Fitting Dimensions ..................................................... 6

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page iv TABLES 1 Prototype Testing ........................................................................................................................... 3 2 20,000 and 25,000 lb SML Dimensions and Electrical Characteristics ..................................... 7 3 36,000 and 40,000 lb SML Dimensions and Electrical Characteristics ..................................... 8

APPENDIX ....................................................................................................................................... 9

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page v



© 2014 National Electrical Manufacturers Association

C29.12-2013 Page 1

AMERICAN NATIONAL STANDARD

ANSI/NEMA C29.12-2013

for Composite Insulators—Transmission Suspension Type 1

SCOPE

This standard covers composite suspension (tension) insulators with a minimum section length of 46 inches (1168.4 mm) made of a fiberglass-reinforced resin matrix core, polymer material weathersheds, and metal end fittings intended for use on overhead transmission lines for electric power systems. Mechanical and electrical performance levels specified herein are requirements for new insulators. 2.

NORMATIVE REFERENCES

2.1

Referenced American National Standards

This standard is intended to be used in conjunction with the following American National Standards. When these standards are superseded by a revision approved by the American National Standards Institute, the revision shall apply. ANSI C29.1-1988 (R2012) Test Methods of Electrical Power Insulators ANSI C29.11-2012 American National Standard for Composite Insulators – Test Methods IEEE 4-1995 Techniques for High Voltage Testing IEEE 100 -1984 Dictionary of Electrical and Electronics Terms 2.2

Other Standards

IEC 60695-11-10 Fire Hazard Testing – Part 11-10: Test Flames – 50 W Horizontal and Vertical Flame Test Methods NEMA Publication Number 107-1987 Methods of measurement of radio influence voltage (RIV) of highvoltage apparatus ISO-3452-1: 2008 Non-Destructive Testing – Penetrant Testing – Part 1: General Principles ASTM B499-09 Standard Test Method for Measurement of Coating Thicknesses by the Magnetic Method; Nonmagnetic Coatings on Magnetic Basis Metals ASTM A153-82 Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware 3

DEFINITIONS AND ABBREVIATIONS

See Section 3 of American National Standard for Composite Insulators – Test Methods, ANSI C29.11 and Section 2 of American National Standard Test Methods for Electrical Power Insulators, ANSI C29.1 for definition of terms not defined here. 3.1

Specified Mechanical Load (SML)

The SML is a value that has to be verified during a tensile load test. It forms the tensile loading basis for selection of a composite suspension insulator. 3.2

Routine Test Load (RTL)

The RTL is a load equal to 50% of the SML. Abbreviations used in this document include: • mA – milliamperes • rms – root-mean-square © 2014 National Electrical Manufacturers Association

C29.12-2013 Page 2 • • 4

s – second mm – millimeters GENERAL

4.1 Insulators shall conform in all respects to the requirements of this standard. The text, figures, and tables supplement each other and shall be considered part of this standard. 4.2 Manufacturer’s drawings, if furnished, shall show the outline of the insulators, together with all pertinent dimensions, and mechanical, electrical, and leakage values. Any variations in these dimensions due to manufacturing tolerances shall be indicated. 5

MATERIALS

5.1

Core

The core is the internal insulating part of a composite insulator. It is intended to carry the mechanical load. It consists mainly of glass fibers positioned in a resin matrix to develop mechanical strength. 5.2

Weathersheds

The weathersheds shall be made of polymer materials such as ethylene propylene or silicone elastomers. They may contain inorganic fillers and organic compounding agents. 5.3

Metal Parts

Metal parts, except for cotter keys, shall be made of a good commercial grade of malleable iron, ductile iron, steel, or aluminum. All ferrous parts, other than stainless steel, shall be galvanized in accordance with specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware ASTM A153 (latest revision). Cotter keys shall be made from cold-drawn bronze, brass, or austenitic stainless steel wire. 6

DIMENSIONS AND CHARACTERISTICS

6.1 Dimensions and characteristics of the insulators shall be in accordance with manufacturers’ drawings. General tolerances shall be in accordance with ANSI C29.11 section 5. End fittings shall be in accordance with figure 1 or meet the ball and socket gauge requirements shown in figures 4, 5, 6, 7 and 8 of ANSI C29.2B. Requirements for a specific ANSI class shall be as shown in tables 1 or 2. The shapes of the weathersheds and spacing between them are not part of this standard. 6.2 Insulator end fittings of the Y-Clevis type (Fig. 1) shall be furnished with a bolt and nut, with a humptype cotter key installed in the clevis bolt. 6.3 All dimensions and other numerical values are given in customary English units except as otherwise stated. NOTE: GRADING FOR CONTROL OF RIV AND CORONA (ELECTRIC FIELD) MAY BE APPROPRIATE FOR COMPOSITE INSULATORS. 7

MARKING

Each insulator shall be clearly and indelibly marked with the name or trademark of the manufacturer, the year of manufacture, the specified mechanical load (SML) with appropriate units, and the routine test load (RTL) with appropriate units. The routine test load shall be identified by the word “TEST”.

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page 3

8

PROTOTYPE TESTS

Prototype tests are required to verify the suitability of the materials and method of manufacture for composite insulators defined by the following characteristics: These tests are described and specified in ANSI C29.11, Section 4.1 and 7. (1a) same shed material (1b) same housing material (2) same core material (3) same core diameter (4) same metal fitting material (5a) same metal fitting connection zone design (5b) same core-metal-housing interface (6) same metal fitting method of attachment to core To allow for manufacturing variations, (3) may vary up to 15% before the design tests must be repeated except as noted below. Retesting is not required for greater thickness of housing. Retesting is also not required for a longer connection zone. Retesting is required for an increase in strength ratings. The materials and methods of manufacture for insulators shall be qualified by successful completion of the following tests. Design changes shall be tested as listed in table 1. If the insulator design changes the…. (1a) (1b) (2) (3) (4) (5a)

Shed Material Housing Material Core Material Core Diameter Metal Fitting Material Metal Fitting Connection Zone Design (5b) Core-Metal-Housing Interface (6) Metal Fitting method of Attachment to Core

Then the following design prototype tests shall be repeated: 8.1 8.2 8.3 8.4 8.5 X X X X X X X X X X X X X X X X X X X X

X

Table 1 – Prototype Testing For successful completion of the prototype tests, insulators of specific design shall be subjected to tests described in this section. Tests described in section 9 are performed by agreement between the manufacturer and customer on insulators of new design. Tests described in section 10 shall be required on each lot of insulators manufactured. Tests described in section 11 shall be conducted on each insulator manufactured. 8.1 Tests on Interfaces and Connection of End Fittings Three suspension insulators shall be tested in accordance with section 7.1 of ANSI C29.11. At the conclusion of the low frequency dry flashover voltage test prescribed in ANSI C29.11, section 7.1.6.3, the temperature rise of the shank section (measured immediately after the test) shall not be more than 10 °C above the ambient temperature. 8.2 Core Time-Load Test Six suspension insulators shall be tested in accordance with section 7.2 of ANSI C29.11.

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page 4

8.3 Housing Tracking and Erosion Tests Two suspension insulators shall be tested in accordance with section 7.3 of ANSI C29.11. After removal from the chamber, the insulators shall be visually inspected. No tracking is allowed. No weathershed punctures are allowed. Erosion is not allowed to reach the core. 8.4 Core Material Tests The dye penetration test and the water diffusion test shall be performed in accordance with section 7.4 of ANSI C29.11. 8.4.1 Dye Penetration Evaluation The time for the dye to rise through the samples by capillarity shall be more than 15 minutes. 8.4.2 Water Diffusion Test Evaluation No puncture or surface flashover is allowed. The current during the whole test shall not exceed 1 mA r.m.s. 8.5 Flammability Test Samples of the elastomeric materials of the insulator shall be tested in accordance with section 7.5 of ANSI C29.11. The materials shall meet the requirements of FV0 (per IEC 60695-11-10). 9

DESIGN TESTS

Design tests for composite insulators are classified as electrical tests. The electrical design of composite insulators is defined by the following characteristics: (1) (2) (3) (4) (5)

Dry arcing distance Leakage distance Weathershed inclination Weathershed diameter Weathershed spacing

The insulator test specimens will be mounted for these tests in accordance with section 3.1 of ANSI C29.1, except that the upper surface of the energized electrode shall be 4-8 inches (100-200 mm) from the connection point of the lower end fitting. 9.1

Low-Frequency Dry Flashover Test.

One composite insulator shall be selected and tested in accordance with 8.2.1 of ANSI C29.11. Failure of the dry flashover value to equal or exceed 95% of the rated dry flashover value, as given on the manufacturer's drawing, shall constitute failure to meet the requirements of this standard. 9.2

Low-Frequency Wet Flashover Test.

One composite insulator shall be selected and tested in accordance with 8.2.2 of ANSI C29.11. Failure of the wet flashover value to equal or exceed 90% of the rated wet flashover value, as given on the manufacturer's drawing shall constitute failure to meet the requirements of this standard. 9.3

Critical Impulse Flashover Tests- Positive and Negative

One composite insulator shall be selected for the critical impulse flashover test, positive, and one for the critical impulse flashover test, negative, and tested in accordance with 8.2.6 of ANSI C29.11. Failure of the critical impulse flashover value to equal or exceed 92% of the rated critical impulse flashover value, as given on the manufacturer's drawing, shall constitute failure to meet the requirements of this standard.

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page 5

9.4

Radio-Influence Voltage

RIV testing shall be performed on one insulator in accordance with 8.2.8 of ANSI C29.11. The radio influence voltage (RIV) shall not exceed 100 microvolts when the insulator is energized at 115% of nominal line-toground voltage. 10

QUALITY CONFORMANCE TESTS

Samples for quality conformance shall be selected at random from each lot except that samples for mechanical load tests shall only be representative and may be of reduced length. A representative sample for mechanical load tests is one in which: • •

•

The diameter of the test insulator rod core is identical to that of the insulators in each lot. The test insulator rod core is identical in material and manufacturing process to that of the insulators in each lot. The insulator end fittings are identical in material, design, manufacturing process and assembly process to those of the insulators in each lot. The test insulator section length is 20 inches (508 mm) or longer.

10.1

Dimensional Tests

•

Three insulators shall be selected at random from the lot and their dimensions checked against the dimensions on the manufacturer's drawing. Section 5 of ANSI C29.11 shall apply to all dimensions without tolerances specified by the manufacturer. Failure of more than one of these insulators to conform within tolerance to the dimensions on this drawing shall constitute failure to meet the requirements of this standard. 10.2

Galvanizing Test

Three pieces representative of each type of galvanized hardware used with the insulators shall be selected at random and tested in accordance with section 9.6 of ANSI C29.11. Five to ten measurements shall be randomly distributed over the entire surface of each of the samples. 10.3

Specified Mechanical Load Test

Three insulators shall be selected in accordance with section 10 above and tested in accordance with 9.4.2 of ANSI C29.11. The test is passed if no failure occurs. 11

ROUTINE TESTS

11.1

Tension-Proof Test

Each assembled insulator shall be subjected to a tension-proof test in accordance with 10.1.1 of ANSI C29.11. The load to be applied shall be equal to or greater than the Routine Test Load. All insulators that fail do not meet the requirements of this standard. 11.2

Visual Examination

Each assembled insulator shall be subjected to a visual examination in accordance with 10.2 of ANSI C29.11. All insulators not in conformance with this section do not meet the requirements of this standard.

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page 6

Figure 1 – Oval-Eye End Fitting and Y-Clevis End Fitting Dimensions

SML RATINGS

A min

B min

C max

D max

E max

F min

20,000 LBS 25,000 LBS

0.94

1.88

.75

.75

.75

.94

36,000 LBS 40,000 LBS

0.98

1.94

.88

.88

1.03

1.38

NOTE: ALL DIMENSIONS ARE IN INCHES. ANSI BALL AND SOCKET (NOT SHOWN) SHALL CONFORM TO DIMENSIONS SPECIFIED IN C29.2B.

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page 7

ANSI class

60-1 60-2 60-3 60-4 60-5 60-6 60-7 60-8 60-9 60-10 60-11 60-12 60-13 60-14

Table 2 - 20,000 or 25,000 lbs. SML, Oval Eye-Ball End Fitting Combination Section Length Minimum Electrical Values Nominal Range Dry Arc Low Frequency Flashover Critical Impulse Flashover Distance Inches Inches Dry Wet Positive Negative (mm) (mm) (kV) (kV) (kV) (kV) 35 46.0 - 50.0 365 310 610 585 (900) [1168 - 1270] 39 51.0 - 54.5 410 350 675 670 (996) [1295 - 1384] 45 57.0 - 60.5 470 415 780 760 (1151) [1448 - 1537] 50 62.5 - 65.5 485 455 860 845 (1270) [1587 - 1664] 54 68.0 - 71.5 560 490 925 930 (1371) [1727 - 1816] 59 73.0 - 77.5 620 545 1025 1015 (1498) [1854 - 1968] 64 79.0 - 83.0 670 580 1105 1105 (1625) [2007 - 2108] 69 84.0 - 89.0 720 620 1185 1190 (1752) [2134 - 2235] 78 93.0 - 99.0 810 690 1345 1360 (1981) [2362 - 2515] 87 104.0 - 108.0 900 755 1490 1530 (2209) [2642 - 2743] 92 109.0 - 115.0 925 795 1575 1600 (2336) [2769 - 2896] 97 115.0 - 120.2 980 830 1665 1700 (2463) [2921 - 3053] 106 126.0 - 137.5 1060 890 1825 1870 (2694) [3200 - 3492] 147 175.0 - 184.2 1345 1290 2530 2630 (3735) [4445 - 4679]

NOTES: 1 ELECTRICAL VALUES AND MINIMUM DRY ARC DISTANCE GIVEN ARE WITHOUT CORONA RINGS. 2 THE SECTION LENGTH AND NOMINAL RANGE SHOWN CORRELATE TO A STRING OF 5 3/4" PORCELAIN/GLASS (CERAMIC) SUSPENSION INSULATORS OF CLASS 52-3 OR 52-5 (ANSI C29.2B) OF THE SAME LENGTH WITH RESPECT TO LOW FREQUENCY (60HZ WET FLASHOVER) ELECTRICAL PERFORMANCE. THE CRITICAL IMPULSE FLASHOVER VOLTAGES SHOWN ARE TOWER THAN THOSE FOR AN EQUIVALENT LENGTH OF CERAMIC INSULATORS. 3 DUE TO INSUFFICIENT INFORMATION REGARDING THE LEAKAGE DISTANCE REQUIRED FOR COMPOSITE INSULATORS, MOST USERS HAVE SPECIFIED LEAKAGE DISTANCE OF COMPOSITE INSULATORS TO BE GREATER THAN OR EQUAL TO EXISTING CERAMIC INSULATOR STRINGS. 4 NOMINAL SECTION LENGTH APPLIES ONLY TO OVAL EYE-BALL END FITTING COMBINATIONS. OTHER END FITTING COMBINATIONS MAY RESULT IN SECTION LENGTHS OUTSIDE OF THE NOMINAL RANGE. © 2014 National Electrical Manufacturers Association

C29.12-2013 Page 8

ANSI class

70-1

70-2

70-3

70-4

70-5

70-6

70-8

70-11

Table 3 - 36,000 or 40,000 lbs. SML, Oval Eye-Ball End Fitting Combination Section Length Minimum Electrical Values Nominal Range Dry Arc Low Frequency Flashover Critical Impulse Flashover Distance Inches Inches Dry Wet Positive Negative (mm) (mm) (kV) (kV) (kV) (kV) 60 77.0 - 81.0 (1524) 625 495 1025 1015 [1956 - 2057] 69 87.0 - 92.0 (1752) 720 620 1185 1190 [2210 - 2311] 76 97.0 - 102.0 (1930) 800 680 1315 1360 [2464 - 2591] 85 106.0 - 112.0 (2159) 885 745 1460 1530 [2794 - 2845] 97 121.0 - 124.0 (2463) 985 830 1665 1700 [3073 - 3124] 106 130.0 - 137.0 (2692) 1045 895 1825 1870 [3327 - 3454] 115 141.0 - 149.0 (2921) 1135 955 1985 2040 [3581 - 3785] 142 182.0 - 187.0 (3606) 1330 1175 2450 2550 [4622 - 4750]

NOTES: 1 ELECTRICAL VALUES AND MINIMUM DRY ARCING DISTANCE GIVEN ARE WITHOUT CORONA RINGS. 2 THE SECTION LENGTH AND NOMINAL RANGE SHOWN CORRELATE TO A STRING OF 5 3/4" PORCELAIN/GLASS (CERAMIC) SUSPENSION INSULATORS OF CLASS 52-8 (ANSI C29.2B) OF THE SAME LENGTH WITH RESPECT TO LOW FREQUENCY (60HZ WET FLASHOVER) ELECTRICAL PERFORMANCE. THE CRITICAL IMPULSE FLASHOVER VOLTAGES SHOWN ARE TOWER THAN THOSE FOR AN EQUIVALENT LENGTH OF CERAMIC INSULATORS. 3 DUE TO INSUFFICIENT INFORMATION REGARDING THE LEAKAGE DISTANCE REQUIRED FOR COMPOSITE INSULATORS, MOST USERS HAVE SPECIFIED LEAKAGE DISTANCE OF COMPOSITE INSULATORS TO BE GREATER THAN OR EQUAL TO EXISTING CERAMIC INSULATOR STRINGS. 4 NOMINAL SECTION LENGTH APPLIES ONLY TO OVAL EYE-BALL END FITTING COMBINATIONS. OTHER END FITTING COMBINATIONS MAY RESULT IN SECTION LENGTHS OUTSIDE OF THE NOMINAL RANGE.

© 2014 National Electrical Manufacturers Association

C29.12-2013 Page 9

APPENDIX (This Appendix is not part of American National Standard C29.12-2013, but is included for information only.) Packaging Packaging of insulators should be such as to afford reasonable and proper protection to the insulators in shipping and handling. Each box or container should be marked with the number of pieces contained therein; the catalog number, or class number, or description of the contents; and the manufacturer’s name.

© 2014 National Electrical Manufacturers Association