NEMA C29 1-2018 Test Methods for Electrical Power Insulators.pdf

1、NEMA Standards PublicationNational Electrical Manufacturers AssociationANSI/NEMA C29.1-2018Test Methods for Electrical Power InsulatorsApproved as an American National Standard ANSI Approval Date of Final Action: January 8, 2018 ANSI/NEMA C29.1-2018 American National Standard for Test Methods for El

2、ectrical Power Insulators Published by National Electrical Manufacturers Association 1300 North 17thStreet, Suite 900 Rosslyn, VA 22209 www.nema.org 2018 National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the Universal Copyright Conv

3、ention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. 2018 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus

4、 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 gui

5、deline 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 admin

6、isters 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 guidel

7、ine 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

8、 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 pe

9、rformance of any individual manufacturer or sellers 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 perfor

10、m 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 stan

11、dards 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. NEM

12、A 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 safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier

13、 or maker of the statement. ANSI/NEMA C29.1-2018 Page i 2018 National Electrical Manufacturers Association Foreword (This foreword is not part of American National Standard C29.1-2016) This standard comprises a manual of procedures to be followed in making tests to determine the characteristics of i

14、nsulators used on electric power systems. This standard is not an insulator specification, but rather a test method to be used in conjunction with insulator specifications. Suggestions for improvement of this standard will be welcome. They should be sent to National Electrical Manufacturers Associat

15、ion, 1300 North 17thStreet, 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 a

16、pproval. At the time it approved this standard, the ASC C-29 Committee had the following members: Arjan Jagtiani, Chairman Gerard Winstanley, Secretary Name Organization Interest Category N. DeSantis Line Works Engineering General T. Grisham GRISCUT, LTD. General A. Jagtiani Sargent it is a specimen

17、 that is undamaged in any way which would Influence the result of the test. 2.5.2 Leakage Distance, The leakage distance of an insulator is the sum of the shortest distances measured along the insulating surfaces between the conductive parts, as arranged for dry flashover test. (Surfaces coated with

18、 semiconducting glaze shall be considered as effective leakage surfaces, and leakage distance over such surfaces shall be included in the leakage distance.) 2.5.3 Dry-Arcing Distance. The dry-arcing distance of an Insulator is the shortest distance through the surrounding medium between terminal ele

19、ctrodes, or the sum of the distances between intermediate electrodes, whichever is the shorter, with the insulator mounted for dry flashover test. 2.5.4 Radio-Influence Voltage. The radio-influence voltage of an insulator is the radio-frequency voltage measured under specified conditions. Radio-infl

20、uence voltage tests are tests as described in 4.9. 3 Test Specimen Mounting for Electrical Tests 3.1 Suspension Insulators 3.1.1 Mounting Arrangement. Unless otherwise specified, the test specimen (unit or string) shall be suspended vertically at the end of a grounded conductor so that the vertical

21、distance from the uppermost point of the insulator hardware to the supporting structure shall be not less than 3 ft. (914 mm). 3.1.2 Energized Electrode. The energized or bottom electrode or conductor shall be a straight, smooth rod or tube having an outside diameter not less than 3/4 inch (19 mm) n

22、or more than 1-1/2 in. (38 mm). It shall be coupled to the lower integral fitting of the test specimen so that the distance from the lowest edge of the insulator shell to the upper surface of the electrode shall be between 0.5 and 0.7 of the diameter of the lowest insulator. The conductor shall be h

23、orizontal and at right angles to the axis of the test specimen. The conductor shall be of such length that flashover will not be initiated at the electrode ends. 3.1.3 Proximity of Other Objects. No objects, other than parts of the test assembly, shall be nearer the test specimen or energized electr

24、odes than 1 times the test-specimen dry-arcing distance, with a minimum allowable distance of 3 ft. (914 mm). ANSI/NEMA C29.1-2018 Page 4 2018 National Electrical Manufacturers Association 3.2 Line Insulators (Pin, Post) 3.2.1 Mounting Arrangement (Crossarm). Unless otherwise specified, the supporti

25、ng crossarm shall be a horizontal, straight, smooth, grounded, metallic tube or structural member having a horizontal width not less than 3 in. (76 mm) nor more than 6 in. (152 mm). It shall be of such length that flashover will not be initiated at its ends. 3.2.2 Mounting Pin (if required). When a

26、separable pin is required, the test specimen shall be mounted vertically on a 1-in. (25-mm) diameter metal pin of such length that the shortest dry-arcing distance from the upper electrode and connected metallic parts to the supporting crossarm shall be 25% greater than the similar distance to the p

27、in. The pin shall be coaxial with the test specimen. Insulators having integrally assembled means for mounting on a cross-arm shall be mounted vertically and directly on the test cross-arm. 3.2.3 Energized Electrode. The energized or top electrode or conductor shall be a horizontal round rod or tube

28、 placed at right angles to the supporting cross-arm and of a diameter not less than .5 in. (13 mm). It shall be of such length that flashover will not be initiated at its ends. The conductor shall be placed in the top conductor groove of the test specimen. When there is no top conductor groove, the

29、conductor shall be placed in the other means provided for the conductor support. If a tie wire is to be used, the conductor shall be secured by means of at least two turns of wire not smaller than No. 8 AWG (American Wire Gage); the ends being closely wrapped around the conductor on each side of the

30、 Insulator. 3.2.4 Proximity of Other Objects. No objects, other than parts of the test assembly, shall be nearer the test specimen or energized electrodes than 1 times the test-specimen dry-arcing distance, with a. minimum allowable distance of 3 ft. (914 mm). 3.3 Apparatus Insulators (Cap and Pin,

31、Post) 3.3.1 Mounting Arrangement. Unless otherwise specified, the test specimen shall be mounted vertically upright on a horizontal, grounded 10-in. (254-mm) channel, with the channel flanges projecting down. A subbase shall be used if the insulator characteristics are predicated on its use. The sup

32、porting channel shall be of such length that flashover will not be initiated at its ends, and its top surface shall be not less than 3 ft. (914 mm) above the ground. 3.3.2 Energized Electrode. The energized or top electrode or conductor shall be a horizontal round rod or tube at right angles to the

33、supporting channel and of a diameter approximately 5% of the test-specimen dry-arcing distance within the limits of 4-1 /2 in. (114 mm) maximum and 1/2 inch (13 mm) minimum. The length of the conductor shall be such that flashover will not be initiated at its ends. It shall be mounted directly in co

34、ntact with the top integral fitting of the test specimen, and with its horizontal axis in the same vertical plane as the vertical axis of the test specimen. 3.3.3 Proximity of Other Objects. No objects, other than parts of the test assembly, shall be nearer the test specimen or energized electrodes

35、than 1-1/2 times the test-specimen dry-arcing distance, with a minimum allowable distance of 3 ft. (914 mm). 3.4 Strain Insulators 3.4.1 Mounting Arrangement. Unless otherwise specified, the test specimen shall be mounted in a position with its major axis at 45 degrees from the vertical (for wet fla

36、shover test, the major axis shall be at right angles to the spray direction, and the axis of the upper conductor hole or slot shall be horizontal), using flexible metal conductors of approximately 50% of the hole diameter. The conductors shall be clamped with guy clamps, spaced from the test specime

37、n at a distance not less than the test-specimen ANSI/NEMA C29.1-2018 Page 5 2018 National Electrical Manufacturers Association length. Mechanical tension sufficient to avoid appreciable sag in the setup shall be applied to the test specimen. The lower conductor shall be grounded. 3.4.2 Proximity of

38、Other Objects. No objects, other than parts of the test assembly, shall be nearer the test specimen or energized electrodes than 1 times the dry-arcing distance of the test specimen, with a minimum allowable distance of 1 ft. (305 mm). 3.5 Spool Insulators 3.5.1 Mounting Arrangement. The test specim

39、en shall be mounted horizontally or vertically as specified in Fig. 1 through 5 of American National Standard for Wet-Process Porcelain Insulators (Spool Type), ANSI C29.3, and in contact with two smooth metallic straps 1.5 in. (38 mm) wide and of any suitable thickness. A rod of suitable diameter s

40、hall pass through the axial hole of the test specimen and one end of each of the straps. The straps shall extend horizontally in one direction from the rod arid remain parallel to each other for a distance from the test specimen of not less than the height of the test specimen. The other ends of the

41、 straps shall be suitably connected to a grounded support. 3.5.2 Energized Electrode, the energized electrode shall consist of one turn of No. 8 AWG conductor placed around the wire groove and served back on itself. This conductor shall be carried away from the test specimen parallel to and in a dir

42、ection opposite to the supporting straps. 3.5.3 Proximity of Other Objects. No objects, other than parts of the test assembly, shall be nearer to the test specimen or energized electrodes than 1 ft. (305 mm). 4 Electrical Tests 4.1 General. Test specimens used for the tests in this section shall hav

43、e clean insulating surfaces. In the absence of a minimum electrical test value within the individual product standard, no individual test value below 75% of the particular rating will be accepted during the performance of electrical tests. Note: Insulators historically qualified to their design test

44、 requirements under previous editions of NEMA/ANSI C29.1 do not need to be requalified in accordance with this Clause. 4.2 Low-Frequency Dry Flashover Voltage Tests 4.2.1 Mounting Arrangement. The test-specimen mounting for dry flashover voltage tests shall be in accordance with Section 3. 4.2.2 Vol

45、tage Application. The initial applied voltage may be quickly raised to approximately 75% of the expected average dry flashover voltage value. The continued rate of voltage increase shall be such that the time to flashover will be not less than 5 seconds nor more than 30 seconds after 75% of the flas

46、hover value is reached. 4.2.3 Dry Flashover Voltage Value. The dry flashover voltage value of a test specimen shall be the arithmetical mean of not less than five individual flashovers taken consecutively. The period between consecutive flashovers shall be not less than 15 seconds or more than 5 min

47、utes. The dry flashover voltage test value shall be corrected to standard conditions in accordance with 4.2.4.1. Note: Probable variation: Due to Inaccuracies of correction methods, difficulties of precise calibrations, and other uncontrollable conditions, a variation of 5% from the probable true av

48、erage dry flashover voltage value may occur in tests conducted in one laboratory. Values obtained by tests conducted in different laboratories may vary by 8%. ANSI/NEMA C29.1-2018 Page 6 2018 National Electrical Manufacturers Association 4.2.4 Corrections 4.2.4.1 Standard Conditions. Dry flashover v

49、oltage test values shall be corrected in accordance with subsection 13.2.2 Atmospheric correction using Method 2 of American National Standard Techniques for High-Voltage Testing, ANSI/IEEE 4, except the following standard conditions shall apply: Barometric pressure: 29.92 in. of mercury, (101.3 kPa) Temperature: 77F (25C) Absolute humidity: 9.34 10-4lbs./ft.3(15 g/m3) Test values obtained (V) at ambient atmospheric conditions shall be corrected to values (Vs) at standard conditions as follows: Vs = (kh/kd)V Humidity (kh) and relative air density (kd) corrections shal