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1、Standard for Installing and Maintaining Liquid-Filled Transformers NECA 410-2005 Published by National Electrical Contractors Association A M E R I C A N N A T I O N A L S T A N D A R D TM Standard for Installing and Maintaining Liquid-Filled Transformers NECA 410-2005 An American National Standard
2、Published by National Electrical Contractors Association i I Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iii 1.Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3、 . . . . . . . . . . . . . . . . . . . . . . . .1 1.1Products and Applications Included . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1.2Products and Applications Excluded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4、 . . . . . . . . . . . . . . . . . . . . . . . . .1 1.3Regulatory Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 2.Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5、. . . . . . . . . . . . . . . . . . . . . . . . . . 2 3.Receiving, Inspecting, Handling, and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1Receiving and Inspecting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6、 . . . . . . . . . . . . . . . . . . .4 3.2Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 3.3Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 3.4Pre-Installation Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 4.Installation . . . . . . . . . . . . . . . . . . .
8、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1General Installation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 4.2Transformer Pad and Mounting . . . . . . . . . . .
9、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 4.3Grounding and Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 4.4 Lighting Arresters . . . . . . . . . .
10、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 4.5Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 5.Inspecting
11、, Testing, and Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 5.1Visual and Mechanical Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 5.2Acceptance Testing . . . . . . .
12、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 5.3Restore Transformer Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 5.4Energizing T
13、ransformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 6.Project Close-Out Deliverables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 6.1Test Data and Manuals
14、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 6.2Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、. . .14 6.3Spare Parts and Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 7.Inspections and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 7.1Sa
16、fety Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 7.2General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、 . . . . . . . . . . . . . .16 7.3First Year of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 7.4Routine Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . . . . . . . . . . . . . . . . . . . . . . . .17 Table of Contents I ii 7.5Annual Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 7.6Comprehensive Electrical Testing . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 7.7Re-energizing Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 7.8Operating Transformer Switches . . . . . . . . .
20、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 7.9Reconnectable Terminations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 8.Inspection and Re-energizing After Adverse
21、 Operating Conditions . . . . . . . . . . . . . . . . . . . .23 8.1Inspection and Testing Following a Short-Circuit or Ground-Fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 8.2Transformer Soaked By or Submersed Under Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、. . . . . . . . . . . . .23 9.Electrical and Thermal Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 9.1General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . . . . . .24 9.2Contact Resistance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 9.3Insulation Resistance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . . . . . . . . . . . . . . . . . . . .24 9.4Polarization and Dielectric Absorption Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 9.5Turns Ratio Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 9.6Excitation Current Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 9.7Winding Resistance Test . . . . . . . . . . . . . . . . . . . . . . . .
26、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 9.8Insulation Power Factor Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 9.9Core Insulation Resistance Test . . . . . . . . . . .
27、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 9.10High Potential Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 9.11Infrared Scan . . . . . . . .
28、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 10.Sampling and Testing of Insulating Liquid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 10.1General . . . . . . . . . . . . .
29、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 10.2Sampling for Insulating Liquid Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 10.3Sampling for D
30、issolved Gas Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 10.4Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31、 .31 Annex A: Overview of Dissolved Gasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Annex B: Reference Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 NECA 410Standard for Install
32、ing and Maintaining Liquid-Filled Transformers iii I National Electrical Installation Standardsare designed to improve communication among speci- fiers, purchasers, and suppliers of electrical construc- tion services. They define a minimum baseline of quality and workmanship for installing electrica
33、l products and systems. NEIS are intended to be ref- erenced in contract documents for electrical con- struction projects. The following language is recom- mended: Liquid-filled transformers should be installed in accordance with NECA 410-2005, Standard for Installing and Maintaining Liquid-Filled T
34、ransformers (ANSI). Use of NEISis voluntary, and the National Electrical Contractors Association assumes no obligation or lia- bility to users of this publication. Existence of a stan- dard shall not preclude any member or nonmember of NECA from specifying or using alternate con- struction methods p
35、ermitted by applicable regula- tions. This publication is intended to comply with the edi- tion of the National Electrical Code (NEC) in effect at the time of publication. Because they are quality standards, NEIS may in some cases go beyond the minimum safety requirements of the NEC. It is the respo
36、nsibility of users of this publication to comply with state and local electrical codes when installing electrical products and systems. Suggestions for revisions and improvements to this standard are welcome. They should be addressed to: NECA Codes and Standards 3 Bethesda Metro Center, Suite 1100 B
37、ethesda, MD 20814 (301) 215-4521 telephone (301) 215-4500 fax www.neca-neis.org neisnecanet.org To purchase National Electrical Installation Standardscontact the NECA Order Desk at (301) 215-4504 tel, (301) 215-4500 fax, or orderdesknecanet.org. Copyright 2005, National Electrical Contractors Associ
38、ation.All rights reserved. Unauthorized repro- duction prohibited. National Electrical Installation Standards and NEIS are trademarks of the National Electrical Contractors Association. National Electrical Code and NEC are regis- tered trademarks of the National Fire Protection Association, Quincy,
39、Massachusetts. Cover illustration courtesy of Niagara Transformers. Foreword (This foreword is not a part of the standard) 1 I 1.1 Products and Applications Included This recommended practice describes installation procedures for pad-mounted, sealed, self-cooled, compartmental, single- and three-pha
40、se liquid-filled distribution and power transformers with primary windings rated from 2400 Volts to 35 kV AC, nomi- nal, and rated from 75 kVA through 5000 kVA, and associated accessories, designed for outdoor installa- tion at grade level with underground entrance of pri- mary and secondary conduct
41、ors, and used for sup- plying power, heating and lighting loads for commer- cial, institutional, and industrial use in nonhazardous locations. It also covers periodic routine maintenance proce- dures for transformers, and special procedures used after adverse operating conditions such as a short- ci
42、rcuit, ground-fault, or immersion in water. 1.2 Products and Applications Excluded This publication does not apply to the following: 1. Dry-type transformers, 2. Specialty transformers such as control, indus- trial control, instrument, current, potential, metering, buck-boost transformers, or lighti
43、ng and ballast transformers, 3. Autotransformers, 4. Cast coil transformers, 5. Arc furnace transformers, 6. Rectifier transformers, 7. Network transformers, 8. Unit substation transformers, or 9. Transformers with more than two sets of windings. 1.3 Regulatory and Other Requirements All information
44、 in this publication is intended to conform to the National Electrical Code (ANSI/NFPA 70). Installers should always follow the NEC, applicable state and local codes, manufacturers instructions, and contract documents when installing liquid-filled transformers. Only qualified persons familiar with t
45、he construction and installation of liquid-filled transformers should perform the work described in this publication. General requirements for installing electrical prod- ucts and systems are described in the latest version of NECA 1, Standard Practices for Good Workmanship in Electrical Contracting
46、 (ANSI). Other National Electrical Installation Standards provide additional guidance for installing particular types of electrical products and systems. A complete list of NEIS is provided in Annex B. 1. Scope I 2 2. Definitions Askarel Transformer coolant identified by various brand names that con
47、sists largely of polychlori- nated biphenyls (PCBs). Subject to strict governmental regulation as a toxic substance. No longer offered in newly manufactured transformers. Dead FrontA terminal or connection that is fully insulated, and that has no exposed, energized compo- nents. Delta-Wye Switch Opt
48、ional transformer switch that is used to change the con- figuration of the primary winding from a Delta configu- ration to a Wye configuration. Dual VoltageTransformer that is equipped Transformer with an internal switch that changes the primary voltage class taps of the transformer, such as from 4,
49、160 Volts to 12,470 Volts. Dry-TypeA transformer in which the Transformer core and windings are cooled by a medium other than a liq- uid, such as a gaseous or dry compound insulating medium. Dry-TypeA transformer in which the Transformer core and windings are cooled by a medium other than a liq- uid, such as a gaseous or dry compound insulating medium. DistributionA transformer for transferring Transformer electrical energy from a prima- ry distribution circuit to a sec- ondary distribution circuit. Distribution transformers are usually rated 500 kVA and less. Liquid-FilledA transfo