1、 AN AMERICAN NATIONAL STANDARD NECA 409-2015 Standard for Installing and Maintaining Dry-Type Transformers Published by National Electrical Contractors Association Published by National Electrical Contractors Association Standard for Installing and Maintaining Dry-Type Transformers NECA 409-2015 An
2、American National StandardNOTICE OF COPYRIGHT This document is copyrighted by NECA Reproduction of these documents either in hard copy or soft (including posting on the web) is prohibited without copyright permission. For copyright permission to reproduce portions of this document, please contact NE
3、CA Standards & Safety at (301) 215-4549, or send a fax to (301) 215-4500. OR National Electrical Contractors Association 3 Bethesda Metro Center, Suite 1100 Bethesda, Maryland 20814 (301) 657-3110 Revision History NECA 409-2002 originally published 04/2002 NECA 409-2009 revised 12/2009 NECA 409-2015
4、 revised 08/2015iii n 1. Scope Foreword v 1. Scope 1 1.1 Products and Applications Included .1 1.2 Products and Applications Excluded 1 1.3 Regulatory and Other Requirements 1 1.4 Mandatory Requirements, Permissive Requirements, Quality and Performance Recommendations, Explanatory Material, and Info
5、rmative Annexes.1 2. Definitions 3 3. Safety Procedures . 4 3.1 General 4 3.2 Safe Work Practices 4 3.3 Personal Protective Equipment (PPE) 5 3.4 De-Energizing Electrical Equipment 5 4. Receiving, Handling, and Storage . 6 4.1 Receiving .6 4.2 Handling .6 4.3 Storage .7 4.4 Pre-Installation Checks 7
6、 5. Installation 8 5.1 General 8 5.2 Environmental Conditions 8 5.3 Coordination with Other Trades .8 5.4 Supporting Transformers .9 5.5 General Installation Requirements 9 5.6 Disconnecting Means, Conductor Ampacity, and Overcurrent Protection10 5.7 Electrical Circuit Connections 10 5.8 Grounding a
7、nd Bonding 10 5.9 Transformer Accessories 11 6. Cleaning, Testing, and Commissioning . 12 6.2 Visual and Mechanical Inspection 12 6.3 Transformer Acceptance T esting13 6.4 Energizing Transformers 13 Table of Contentsn iv NECA 409 Standard for Installing and Maintaining Dry-Type Transformers 7. Site
8、Cleanup. 15 7.1 Restoring Transformer Finishes 15 7.2 Test Data and Manuals .15 7.3 Training .15 7.4 Spare Parts and Special Tools 15 8. Inspections and Maintenance 16 8.1 Frequency of Inspections and Maintenance .16 8.2 Routine Inspections .16 8.3 External Cleaning, Inspection, and Maintenance 17 8
9、.4 Internal Cleaning, Inspection, and Maintenance .18 8.5 Transformer Maintenance Testing.19 8.6 Re-energizing Transformers.19 8.7 Final Infrared Scan .19 9. Inspection and Re-energization After Adverse Operating Conditions 20 9.1 Inspection and Testing Following a Short-Circuit or Ground-Fault 20 9
10、.2 Transformers Soaked By or Submersed Under Water 20 9.3 Inspecting and Re-energizing Transformers Sprayed or Splashed with Clean Water 20 10. Drying Transformers . 21 10.1 General 21 10.2 Drying by Internal Heat .21 10.3 Drying by External Heat 21 10.4 Drying by Internal and External Heat 22 10.5
11、Determining Drying Time .22 11.1 General 23 11.2 Contact Resistance Test 23 11.3 Insulation Resistance Test 23 11.4 Turns Ratio Test 23 11.5 Excitation Current Test 24 11.6 Winding Resistance Test.24 11.7 Core Insulation Resistance Test .24 11.8 High Potential Test .24 11.9 Infrared Scan 25 11.10 In
12、sulation Power Factor Test 25 Annex A: Transformer Troubleshooting Guide . 26 Annex B: Recommended Tightening Torque Tables 32 Annex C: Reference Standards 35v n 1. Scope National Electrical Installation Standards (NEIS) are designed to improve communication among specifiers, purchasers, and supplie
13、rs of electrical construction services. They define a minimum baseline of quality and workmanship for installing electrical products and systems. NEIS are intended to be referenced in contract documents for electrical construction projects. The following language is recommended: Dry-type transformer
14、s should be installed and maintained in accordance with NECA 409-2015, Standard for Installing and Maintaining Dry- Type Transformers (ANSI). Use of NEIS is voluntary, and the National Electrical Contractors Association assumes no obligation or liability to users of this publication. Existence of a
15、standard shall not preclude any member or non- member of NECA from specifying or using alternate construction methods permitted by applicable regulations. This publication is intended to comply with the edition of the National Electrical Code (NEC) in effect at the time of publication. Because they
16、are quality standards, NEIS may in some instances go beyond the minimum safety requirements of the NEC. It is the responsibility of users of this publication to comply with applicable federal, state, and local electrical codes when installing electrical products and systems. Installers should also f
17、ollow all manufacturers installation instructions and ensure conformity to electrical ratings marked on such equipment. Suggestions for revisions and improvements to this standard are welcome. They should be addressed to: NECA Standards & Safety 3 Bethesda Metro Center, Suite 1100 Bethesda, MD 20814
18、 (301) 215-4549 (301) 215-4500 Fax www.neca-neis.org neisnecanet.org To purchase National Electrical Installation Standards, contact the NECA Order Desk at (301) 215-4504 tel, (301) 215-4500 fax or orderdesk necanet.org. NEIS can also be purchased in .pdf download format at www.neca-neis.org/standar
19、ds. Copyright 2015, National Electrical Contractors Association. All rights reserved. Unauthorized reproduction prohibited. National Electrical Installation Standards, NEIS, and the NEIS logo are trademarks of the National Electrical Contractors Association. National Electrical Code and NEC are regi
20、stered trademarks of the National Fire Protection Association, Quincy, MA. Foreword (This foreword is not a part of the standard)1 n 1. Scope 1.1 Products and Applications Included This standard describes the installation and maintenance procedures for single- and three- phase general purpose dry-ty
21、pe transformers and associated accessories rated 1000 Volts AC or less, and 0.25 kVA or more. This publication applies to indoor and outdoor, ventilated and non-ventilated, two-winding transformers used for supplying power, heating, and lighting loads for commercial, institutional, and industrial us
22、e in nonhazardous locations both indoors and outdoors. It also covers periodic routine maintenance and troubleshooting procedures for transformers, and special procedures used after adverse operating conditions such as a short-circuit, ground-fault, or immersion in water. 1.2 Products and Applicatio
23、ns Excluded This standard does not include: Transformers with one or more windings rated greater than 1000 Volts AC. Liquid-filled transformers. Autotransformers. Current transformers. Control transformers and transformers used with Class 2 and Class 3 circuits. Dry-type transformers that constitute
24、 a component part of other apparatus and comply with the requirements for such apparatus, including an X-ray, high-frequency, or electrostatic-coating apparatus. Transformers for sign and outline lighting, including electric-discharge lighting. Transformers used for power-limited fire alarm circuits
25、. 1.3 Regulatory and Other Requirements All information in this publication is intended to conform to the National Electrical Code (ANSI/ NFPA Standard 70). Installers shall follow the NEC, applicable state and local codes, and manufacturer instructions, and contract documents when installing dry-ty
26、pe transformers. Only qualified persons as defined in the NEC familiar with the construction and installation of dry-type transformers shall perform the technical work described in this publication. Administrative functions such as receiving, handling and storing required in Section 4, and other tas
27、ks may be performed under the supervision of a qualified person. All work shall be performed in accordance with NFPA 70E, Standard for Electrical Safety in the Workplace. General requirements for installing electrical products and systems are described in NECA 1, Standard for Good Workmanship in Ele
28、ctrical Construction (ANSI). Other NEIS provide additional guidance for installing particular types of electrical products and systems. A complete list of NEIS is provided in Annex B. 1.4 Mandatory Requirements, Permissive Requirements, Quality and Performance Recommendations, Explanatory Material,
29、and Informative Annexes Mandatory Requirements. Mandatory requirements in manufacturer instructions, or of Codes or other mandatory Standards that may or not be 1. Scopen 2 NECA 409 Standard for Installing and Maintaining Dry-Type Transformers adopted into law, are those that identify actions that a
30、re specifically required or prohibited and are characterized by the use of the terms must or must not, shall or shall not, or by the use of positive phrasing of mandatory requirements. Examples of mandatory requirements may equally take the form of, “equipment must be protected,” “equipment shall be
31、 protected,” or “protect equipment,” with the latter interpreted (understood) as “(it is necessary to) protect equipment” Permissive Requirements. Permissive requirements of manufacturer instructions, or of Codes or other mandatory Standards that may or not be adopted into law, are those that identi
32、fy actions that that are allowed but not required, are normally used to describe options or alternative means and methods, and are characterized in this Standard by the use of the terms may or may not, or are permitted or are not required. Quality and Performance Recommendations. Quality and perform
33、ance recommendations identity actions that are recommended or not recommended to improve the overall quality or performance of the installation and are characterized by the use of the term should or should not. Explanatory Material. Explanatory material, such as references to other Codes, Standards,
34、 or documents, references to related sections of this Standard, information related to another Code, Standard, or document, and supplemental application and design information and data, is included throughout this Standard to expand the understanding of mandatory requirements, permissive requirement
35、s, and quality and performance recommendations. Such explanatory material is included for information only, and is identified by the use of the term “Note,” or by the use of italicized text. Informative Annexes. Non-mandatory information, other reference standards or documents relative to the applic
36、ation and use of materials, equipment, and systems covered by this Standard are provided in informative annexes. Informative annexes are not part of the enforceable requirements of this Standard, but are included for information purposes only. 3 n 1. Scope Dry-Type Transformer A transformer in which
37、 the core and windings are cooled by a medium other than a liquid, such as a gaseous or dry compound insulating medium. Indoor Transformer A transformer which, because of its construction, must be protected from the weather. Outdoor Transformer A transformer of weather- resistant construction suitab
38、le for service without additional protection from the weather. Transformer A device consisting of 2 or more coils of insulated wire that transfers alternating current by electromagnetic induction from 1 coil to another to change the original voltage or current value. Ventilated Transformer A transfo
39、rmer constructed to provide ambient air circulation through its enclosure to cool the transformer core and windings. Weathershields Transformer accessories that allow indoor transformers to be installed outdoors. 2. Definitionsn 4 1. Scope Before performing installation, cleaning, inspections, testi
40、ng, maintenance, or repairs, electrically isolate conductors and equipment in accordance with established written procedures. All work and actions must conform to the requirements of NFPA 70E, Electrical Safety in the Workplace. The process of de-energizing is considered “live” work and can result i
41、n an arc flash due to equipment failure. When de-energizing conductors and equipment, follow safety procedures for working on or near live circuits. Failure to observe these precautions may result in severe personal injury or death. 3.1 General For electrical equipment to work properly, it must be h
42、andled carefully and installed, operated, and maintained correctly. Neglecting fundamental installation and maintenance requirements may lead to personal injury or death, and damage to conductors, electrical equipment, and other property. Consider all circuits and ungrounded and grounded metal parts
43、 of equipment and devices to be energized at the highest voltage to which they are exposed unless they are de-energized, tested, and locked out of operation. Equipment shall be rendered safe by following a lock out/tag out procedure that meets OSHA requirements as outlined in NFPA 70E. Do not work o
44、n energized conductors or equipment. Electrically isolate conductors and equipment in accordance with established procedures and manufacturer instructions. Use care in opening and closing doors to energized equipment. Conductors and terminations may be exposed and within the reach of openings. Do no
45、t enter equipment enclosures when components are energized. Do not remove access covers, doors, or panels when equipment is energized. Do not expose conductors, connections, or terminations when components are energized. Using established safety procedures, guard energized conductors and equipment i
46、n close proximity to the work. Electrical equipment may have multiple sources of power, capacitors with stored electric charge, and control circuits from separate sources. Expect hazardous voltages in all interconnecting components and conductors. 3.2 Safe Work Practices Perform preliminary inspecti
47、ons and tests prior to beginning work to determine existing conditions. Check existing conditions against available record documents. Visually verify all cable connections to equipment. Confirm that supply and load cables are connected properly. Keep in mind that transposed cables may be connected t
48、o different terminals than expected. Resolve discrepancies between installed conditions and electrical drawings. Have drawings corrected, if required. Provide warning labels on equipment, cables, and other equipment where necessary to indicate unexpected and potentially hazardous conditions. Maintai
49、n as much distance as practical from equipment and devices that may arc during operation or handling, but not less than the arc flash protection boundary specified in NFPA 70E. 3. Safety Procedures5 n Standard for Installing and Maintaining Dry-Type Transformers NECA 409 Use insulated tools when working on or around energized equipment. Use only properly rated tools for the energy present. Maintain tool inventories to ensure that all tools are accounted for prior to energizing equipment. Ensure that egress from the work area is unobstructed, and t
