NEMA HV 3-2019 Suggested Purchase Specification Guidelines for High Voltage Insulators Published by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 www.nema.org © 2020 National Electrical Manufacturers Association. All rights, 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. © 2020 National Electrical Manufacturers Association NEMA HV 3-2019 Page ii DISCLAIMER The requirements or guidelines presented in this white paper, are considered technically sound at the time they are approved for publication. They are not a substitute for a product seller’s or user’s own judgment with respect to the particular product discussed, and NEMA does not undertake to guarantee the performance of any individual manufacturer’s products by virtue of this document or guide. Thus, NEMA expressly disclaims any responsibility for damages arising from the use, application, or reliance by others on the information contained in these white papers, Standards, or guidelines. © 2020 National Electrical Manufacturers Association NEMA HV 3-2019 Page iii Foreword This document is intended to provide guidelines to those responsible for specifying and purchasing high voltage insulators. However, it is stressed that these are only guidelines and direct consultation between the user and the manufacturer is recommended. The need for this guide was indicated by the knowledge of customers’ experiences which manufacturers of high voltage insulators gained over many years. Your comments are welcomed and should be submitted to: NEMA Technical Operations Department National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 Member Companies Hubbell Power Systems K-Line Insulators USA Inc. Lapp Insulators LLC NGK-Locke Insulators, Inc. PPC USA, Inc. Preformed Line Products Sediver USA, Inc TE Connectivity Victor Insulators, Inc. Shelton, CT Rochester, NY LeRoy, NY Baltimore, MD Houston, TX Mayfield Village, OH West Memphis, AR Harrisburg, PA Victor, NY © 2020 National Electrical Manufacturers Association NEMA HV 3-2019 Page iv CONTENTS 1. Scope and Purpose.......................................................................................................................... 1 2. General............................................................................................................................................. 1 3. Approved Suppliers .......................................................................................................................... 1 4. Supplier’s Quality Assurance Programs .......................................................................................... 2 5. Purchaser’s Standards for Insulators ............................................................................................... 2 6. Shipment Quality Assurance ............................................................................................................ 3 7. Post-sale Commitment ..................................................................................................................... 3 8. Application ........................................................................................................................................ 3 © 2020 National Electrical Manufacturers Association NEMA HV 3-2019 Page 1 1. Scope and Purpose High voltage insulators of the best possible quality are essential to obtain long-term reliable service demanded of today’s electric utility infrastructure. This document describes best practices on the part of purchasers and suppliers of high voltage insulators toward assuring a consistent and reliable supply of best quality high voltage insulators. It is the intent of these guidelines to provide assistance to those responsible for specifying and purchasing high voltage insulators to identify those best quality insulators most suitable for their specific application and service conditions, which can be consistently and reliably supplied. Assurance in obtaining the best quality high voltage insulators is greatly aided if the purchaser has a comprehensive Purchase Specification covering all aspects of the procurement process. Members of the NEMA High Voltage Insulator Section (NEMA 8HV Section) have committed to industry best practices as described in these Guidelines to consistently and reliably supply quality high voltage insulators that are certified with respect to all aspects of their design, manufacture, and testingThis includes a requirement, when so specified, for third-party certification if needed in the opinion of the purchaser, and particularly when a manufacturer lacks the necessary in-house qualified test facilities. There are two main types of high voltage insulators defined in the various American National Standards Institute (ANSI) C29 and the Canadian Standards Association (CSA) CAN C411 and C156 series of insulators Standards; ceramic and non-ceramic insulators. Ceramic insulators include both wet-process porcelain and toughened glass insulators. Non-ceramic insulators, also called polymers, have a reinforced fiberglass core rod with an elastomeric outer housing. Both types are defined in the various ANSI and CSA Standards. While vastly different in design, materials, and production methods, the recommendations given here for items and requirements that should be included in purchase specifications for high voltage insulators are applicable for both types of high voltage insulators. In today’s business environment, high voltage insulators may be obtained directly from on-shore or offshore manufacturers, or from re-sale suppliers. Regardless of the source, purchasers will obtain the best quality insulators if the procedures and requirements described here are strictly applied and followed. 2. General Best quality high voltage insulators are essential components for the reliable operation of overhead electric power line systems and should not be considered as common commodities. While usually of a lower cost of the major components of overhead lines compared to the cost of conductors and towers or poles, high voltage insulators are the critical connection between the two providing both electrical insulation and mechanical support. To assure users that prospective suppliers have the required expertise, facilities, and commitment to consistently and reliably produce and deliver best quality high voltage insulators, purchasing specifications should require that suppliers be approved prior to bidding, that they have a formally certified quality assurance program, and have the financial resources to support a continuing commitment to the electric utility industry. 3. Approved Suppliers Prospective suppliers should be evaluated prior to being placed on a purchaser’s Approved Supplier List. Pre-qualification evaluations should consider a prospective high voltage insulator supplier’s capability to consistently and reliably perform for all aspects of the design, test, and manufacture of its high voltage insulator products. Since a supplier is sometimes not directly the manufacturer, an approval process should specifically target and identify the factory and actual manufacturer. Many purchasers do require such pre-qualification, which, if effective, includes the following: © 2020 National Electrical Manufacturers Association NEMA HV 3-2019 Page 2 a. References from other current users of a particular supplier’s same, or similar, insulators, from the same factory, to those of interest to the purchaser, ideally in the same type of service conditions and for an extended time, should be obtained and evaluated. b. A prospective supplier’s factory should be visited by a purchaser’s engineering, operations, and purchasing personnel to observe typical production and tests to evaluate the supplier’s resources and ability to make the best quality high voltage insulators. c. A prospective factory/supplier’s quality assurance program and practices, including those incumbent on sub-suppliers, should be thoroughly evaluated. While the requirement to establish and maintain an Approved Supplier List is in the purview of the purchaser, such a list is highly recommended as an aid to procuring the best quality high voltage insulators consistently and reliably. 4. Supplier’s Quality Assurance Programs A formal Quality Assurance (QA) program covering all aspects of a supplier’s operation is essential to demonstrate that the supplier has the requisite ability and resources to consistently and reliably supply the best quality high voltage insulators. During a supplier pre-qualification program: a. A prospective factory/supplier’s QA program should be thoroughly reviewed and should meet the requirements of the International Standards Organization (ISO) Standard 9001 Quality Management Systems – Requirements or equivalent to the purchaser’s satisfaction. b. A factory/supplier’s QA program should be certified as meeting the requirements of ISO 9001, or equivalent, by a third-party independent certifying organization such as one qualified by ANSI/ASQ National Accreditation Board (ANAB) or similar organization. c. A prospective factory/supplier should have, or use, product test facilities that are also certified as meeting the requirements of ISO 9001 and/or those given in ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories or equivalent certification. d. Certifications must have been kept current over a period of time to the purchaser’s satisfaction. 5. Purchaser’s Standards for Insulators To assure consistency and reliability from its supplier of high voltage insulators, there should be a current engineering Standard, issued by the purchaser’s appropriate company department or group, giving the dimensional, electrical, and mechanical requirements for each type of insulator used. A good way to accomplish this is to reference the applicable ANSI C29 or CSA CAN C411 and C156 series of insulator Standards in the purchaser’s current engineering Standard. a. The appropriate ANSI C29 or CSA CAN C411 and C156 insulator Standard and class should, if possible, be adopted as part of the purchase specification. b. In some applications, high voltage insulators of design or configuration different than those currently defined in the Standards may be required. Engineering competence, demonstrated by experience, in providing such solutions for all aspects of design, manufacture, and application of high voltage insulators, should be required of prospective suppliers. c. Application-specific requirements, such as longer leakage distance due to atmospheric or local manufacturing pollution, extreme wind and/or ice loading, etc. should be included in the purchase specification as appropriate. References obtained in the pre-qualification phase can be particularly useful in determining if a prospective factory/supplier has the requisite experience to recommend suitable insulators for a given application. © 2020 National Electrical Manufacturers Association NEMA HV 3-2019 Page 3 d. Pre-qualification of a supplier’s particular insulator with respect to design and type tests can be useful, and provide a basis for an approved insulator list, provided all tests are performed and certified to be in accordance with the appropriate ANSI or CSA Standards. e. A supplier that provides insulators on a re-sale basis should accept responsibility as if the actual manufacturer of the product and qualified as such. The actual factory/country of origin of the insulators should be clearly established and identified in all documents related to qualification, testing, and approval. 6. Shipment Quality Assurance Quality assurance tests on samples from shipments of insulators, segregated by lots, performed in accordance with the appropriate ANSI C29 or CSA CAN C411 and C156 series of insulator Standards should be required to be submitted to the purchaser at the time of shipment. Re-sale suppliers should be required to demonstrate that insulators offered are qualified for acceptance in accordance with the purchase specification and appropriate ANSI or CSA Standards. This may require tests to be conducted by a qualified laboratory independent of the actual manufacturer. 7. Post-Sale Commitment Purchase specifications should require that suppliers submit evidence that they are capable of responding to the purchaser’s questions or product performance or warranty claims after the sale of high voltage insulators should that become necessary. The purchaser should perform a review of the availability of the supplier’s personnel to respond in a timely manner to the purchaser in person and provide a remedy if required. Additionally, details of liability and other types of insurance, such as umbrella, marine, and transit, etc., carried by the supplier should be reviewed and documented, including any third body certification or rating. 8. Application High voltage insulators are only one component of overhead electric lines, and users are assumed competent in integrating them into their systems. While the user is primarily responsible for selecting insulators for his particular application, prospective suppliers should demonstrate extensive experience in the application of high voltage insulators and commit to freely sharing their experiences and recommendations with purchasers of their products. § © 2020 National Electrical Manufacturers Association
