UL SUBJECT 1446A-2018 UL Outline of Investigation for Dry Type Transformer Insulation Systems Rated Above 1 kV (Issue 1).pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULJANUARY 30, 20181UL 1446AOutline of Investigation for Dry Type Transformer Insulation Systems RatedAbove 1 kVIssue Number: 1January 30, 2018Summary of TopicsThis first issue of the Outline of Inv

2、estigation for Investigation For DryType Transformer Insulation Systems Rated Above 1 kV, UL 1446A,covers the test procedures used in the evaluation of Class 120(E) orhigher rated electrical insulation systems (EIS) with operating voltages of1 kV and above for use in; open wound, cast coil, resin en

3、capsulatedand pre-preg flexible sheet rolled, dry-type high-voltage transformerswhere the thermal factor is the dominating aging factor and wheretransient over-voltages or partial discharge may be present.ULs Outlines of Investigation are copyrighted by UL LLC. Neither a printed norelectronic copy o

4、f an Outline of Investigation should be altered in any way. All ofULs Outlines of Investigation and all copyrights, ownerships, and rights regardingthose Outlines of Investigation shall remain the sole and exclusive property of ULLLC.COPYRIGHT 2018 UL LLCUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FU

5、RTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULJANUARY 30, 2018UL 1446A2No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULCONTENTSINTRODUCTION1 Scope .42 Units of Measurement .43 References .44 Glossary .5PERFORM

6、ANCE CRITERIA5 Insulation Systems 55.1 General .55.2 EIS components 6PERFORMANCE TESTS6 Electrical Insulation Systems Full Thermal Aging 66.1 General .66.2 Samples .66.3 Exposures .86.4 Diagnostic tests determination of end of test-life 96.5 Analysis and evaluation 10MARKING7 Details 10JANUARY 30, 2

7、018 UL 1446A 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULINTRODUCTION1 Scope1.1 These requirements cover test procedures used in the evaluation of Class 120(E) or higher ratedelectrical insulation systems (EIS) with operating voltages of

8、1 kV and above for use in; open wound, castcoil, resin encapsulated and pre-preg flexible sheet rolled, dry-type high-voltage transformers where thethermal factor is the dominating aging factor and where transient over-voltages or partial discharge maybe present.1.2 This outline is intended to evalu

9、ate a single EIS and establish a Voltage Stress Level (VSL) for thevarious insulation functions tested such as turn-to-turn, layer-to-layer, section-to-section, coil-to-coil andcoil-to-ground. An EIS established under this outline is suitable for all transformers constructed with thisEIS such that t

10、he design maintains the insulation thickness at or below the tested VSL values.1.3 These requirements for the evaluation of an EIS do not establish thermal ratings for/or alterestablished thermal ratings for individual components.1.4 These requirements do not cover insulation systems exposed to radi

11、ation or operating in oils,refrigerants, soaps, or other media that potentially degrade insulating materials.1.5 When any performance aspect of an end-product requirement is not covered by this outline, theapplicable standard shall be used.2 Units of Measurement2.1 Values stated without parentheses

12、are the requirement. Values in parentheses are explanatory orapproximate information.3 References3.1 Any undated reference to a code or standard appearing in the requirements of this outline shall beinterpreted as referring to the latest edition of that code or standard.3.2 The following standards a

13、re used in this outline:a) The Standard for Systems of Insulating Materials General, UL 1446;b) The Test Procedure for Thermal Evaluation of Insulation Systems for Dry-Type Power andDistribution Transformers, Including Open-Wound, Solid-Cast, and Resin-EncapsulatedTransformers, IEEE C57.12.60;c) The

14、 Standard for Electrical Insulation Systems Procedures for Thermal Evaluation Part1: General Requirements Low-voltage, IEC 61857-1;d) The Standard Test Methods for Forced-Convection Laboratory Ovens for Evaluation ofElectrical Insulation, ASTM D5374; ande) The Standard Specification for Forced-Conve

15、ction Laboratory Ovens for Evaluation ofElectrical Insulation, ASTM D5423.JANUARY 30, 2018UL 1446A4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL4 Glossary4.1 For the purpose of this outline, all definitions from the Standard for Systems of

16、Insulating Materials General, UL 1446 and the Standard for Electrical Insulation Systems Procedures for Thermal Evaluation Part 41: Specific Requirements for Electrical Insulation Systems for Use In Dry-Type High-VoltageTransformers with Operating Voltages of 1kV and Above, IEC 61857-41/CD2 apply.PE

17、RFORMANCE CRITERIA5 Insulation Systems5.1 General5.1.1 Electrical insulation systems for use in open wound, cast coil, resin encapsulated and pre-pregflexible sheet rolled dry-type, high-voltage transformers with operating voltages of 1 kV and above shallbe evaluated following the guidelines as set

18、forth in the Standard for Systems of Insulating Materials General, UL 1446. A thermal aging program, test protocol and sample requirements, is specified in thisoutline, for this purpose and to provide specific guidance when developing a test program for this type ofEIS.5.1.2 A secondary coil employe

19、d in a high-voltage transformer is frequently referred to as the low voltagecoil or winding. The secondary coil EIS may operate at 1kV and above and this outline is suitable for thethermal evaluation of this type of coil. For a secondary coil EIS operating below 1 kV, testing may beconducted to this

20、 outline or to the Standard for Systems of Insulating Materials General, UL 1446, thesection for Electrical Insulation Systems Full Thermal Aging.5.1.3 An EIS shall be investigated to determine whether the components within the EIS are compatible,and to establish a temperature class for the EIS that

21、 includes specified voltage stress levels for theinsulating materials used in the EIS.5.1.4 Insulating materials (EIM and NIM) having different assigned temperature class ratings are able tobe combined to form an EIS having a temperature class that is higher or lower than that of any of theindividua

22、l insulating materials.5.1.5 The compatibility of an insulating material with other materials in the same insulation system shallbe investigated to determine whether thermal aging of such components makes the system susceptible tounacceptable deterioration that inhibits intended performance in norma

23、l service at the assignedtemperature class of the system.5.1.6 The compatibility of an EIS with one or more separate EIS in proximity to it shall be investigatedwhen the insulation systems are in direct contact with each other. For example, a transformer primary coilthat is wound directly over and i

24、n contact with the transformer secondary coil.5.1.7 Constructional features, such as mechanical and electrical properties of lead-wire insulation,including thickness and type, thickness and dielectric strength of a component, electrical spacings, andoperating temperatures, shall be evaluated in the

25、end-use product.JANUARY 30, 2018 UL 1446A 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL5.2 EIS components5.2.1 EIS components include but are not limited to, magnet/winding wire, ground insulation, encapsulant,casting resin, varnish/impreg

26、nating resins, wedges, tapes, lead wire, sleeving, and all similar parts usedto construct the transformer coil.5.2.2 For the purpose of documenting materials and determining test model coil construction, informationconcerning EIS components shall be obtained prior to testing. The information shall i

27、nclude:a) Manufacturers name and catalog numbers or the equivalent;b) Thicknesses of EIM components (where appropriate); andc) Other appropriate information.PERFORMANCE TESTS6 Electrical Insulation Systems Full Thermal Aging6.1 General6.1.1 Representative samples of the candidate EIS shall be subjec

28、ted to a full thermal aging, consistingof a minimum of three temperatures. At each of the aging temperatures, samples shall be subjected to acycling program, undergo diagnostic testing, and the data from all temperatures shall be analyzed todetermine a thermal class rating to a fixed correlation tim

29、e of 40,000 h.6.1.2 Additional components not present in the thermally aged samples shall be added by methodsoutlined in the Standard for Systems of Insulating Materials General, UL 1446, the supplement forSubstitutions or Modification to an Electrical Insulation System, Supplement SA.6.2 Samples6.2

30、.1 Test samples of either a production transformer coil or a representative model coil construction shallinclude all EIM components, and any additional NIM components, assembled to represent the intendedend-use EIS. Representative model samples shall be made using the same process as production coil

31、s.Test samples of an open-type EIS are not representative of a cast or resin encapsulated EIS. The TestProcedure for Thermal Evaluation of Insulation Systems for Dry-Type Power and DistributionTransformers, Including Open-Wound, Solid-Cast, and Resin-Encapsulated Transformers, IEEEC57.12.60 provides

32、 examples of test samples suitable for use in this thermal aging program.6.2.2 Design and construction factors of representative model coils are determined by:a) The voltage stress level values that incorporates the highest VSL value for each electricalstress path from that transformer coil family;

33、andb) The size, thickness, and other factors of each EIM being used along each possible electricalstress path.JANUARY 30, 2018UL 1446A6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL6.2.3 The winding configuration of the intended end-use insu

34、lation system is to be represented in the testsamples. Testing of copper conductor is considered representative of aluminum conductor. Testing ofaluminum is not considered representative of copper conductor.6.2.4 The thickness of the insulation used in the test coil is recommended to be 80% to 100%

35、of theinsulation thickness used in the transformer design with the highest VSL in the area being tested(turn-to-turn, layer-to-layer, etc.).6.2.5 The report shall define the different electrical stress paths evaluated and the VSL for each subgroupof the EIS as described in 6.2.6 6.2.11.6.2.6 Electri

36、cal stress path The turn-to-turn dielectric test is conducted between two adjacentconductors, either wire or foil, separated by an electrical insulating material in a bifilar arrangement.6.2.7 Electrical stress path The layer-to-layer dielectric test is conducted between two adjacent layersof insula

37、ted conductor in a transformer winding separated by an electrical insulating material.6.2.8 Electrical stress path The disk-to-disk dielectric test is conducted between two adjacent groupson insulated conductor in a disk wound configuration.6.2.9 Electrical stress path The section-to-section dielect

38、ric test is conducted between two adjacentsections in a layer wound configuration.6.2.10 Electrical stress path The winding-to-winding dielectric test is conducted between two coils (e.g.high voltage coil to low-voltage coil, separated by an electrical insulating material). The low-voltage coilmay b

39、e simulated by a metal ground plane. The separation between two coils may include solid insulationand/or air.6.2.11 Electrical stress path The coil-to-ground dielectric test is conducted between the core and thehigh-voltage winding. The core may be simulated by a metal ground plane. The separation b

40、etween coreand winding may include solid insulation and/or air.6.2.12 After determining the maximum VSL in kV/mm for each electrical stress path for the family of coilsto be evaluated, the dielectric test voltage for each electrical stress path will be the maximum VSL inkV/mm plus 0.5 kV/mm.6.2.13 T

41、he number of samples in a group for each aging temperature shall not be less than three.6.2.14 All parties shall agree upon the sample construction and testing protocol before testing can begin.6.2.15 In order to detect faulty sample configurations or individual defective samples, all samples shall

42、bescreened before thermal aging begins by subjecting all samples to one full exposure cycle, except for theoven aging, then subjected to the appropriate diagnostic tests in accordance with 6.4. Samples that donot meet the requirements in the diagnostic tests in 6.4 shall be eliminated from the test

43、program and shallbe replaced with usable samples such that the number of samples remains in compliance with 6.2.4.JANUARY 30, 2018 UL 1446A 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL6.3 Exposures6.3.1 Heat aging6.3.1.1 For sample that a

44、re aged by oven heating, the thermal-aging ovens used in the aging programare to be calibrated using the methods in the Standard Test Methods for Forced-Convection LaboratoryOvens for Evaluation of Electrical Insulation, ASTM D5374, and comply with the Standard Specificationfor Forced-Convection Lab

45、oratory Ovens for Evaluation of Electrical Insulation, ASTM D5423 for Type I (5 20 air changes per hour) oven, primarily with respect to Rate of Ventilation, Set Temperature,Temperature Variation and Thermal Lag Time.6.3.1.2 For samples that are continuously energized and, as a result, are self-heat

46、ing, the temperature ofa single sample or set of samples shall not vary by more than 2C (3.6F) for temperatures below300C (572F) and 3C (5.4F) for aging temperatures above 300C (572F). The temperatures are tobe measured by a suitable method such as change-of-resistance or by thermocouples located on

47、 thesamples. The aging period is determined to begin when temperature stability is obtained and thetemperatures are within tolerance. Additional guidance on self-heating test coils is provided in the TestProcedure for Thermal Evaluation of Insulation Systems for Dry-Type Power and DistributionTransf

48、ormers, Including Open-Wound, Solid-Cast, and Resin-Encapsulated Transformers, IEEEC57.12.60, the section for Aging by Circulating Electric Current.6.3.1.3 The selection of aging temperatures shall be determined using the Temperature and ExposureTime Guide Table in the Test Procedure for Thermal Eva

49、luation of Insulation Systems for Dry-Type Powerand Distribution Transformers, Including Open-Wound, Solid-Cast, and Resin-EncapsulatedTransformers, IEEE C57.12.60. Deviations from the specified temperature and exposure time shall beagreed upon by all parties. The spread between aging temperatures is to be not less than 10C (18F) inorder to minimize the effect of small errors in measuring and controlling these temperatures.6.3.1.4 The aging temperatures shall be specified with the understanding that by conducting510agingcycles t