1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA WC 52-2005High-Temperature and Electronic Insulated Wire, Impulse Dielectric TestingNEMA Standards Publication WC 52-2005 High-Temperature and Electronic Insulated Wire, Impulse Dielectric Testing Published by: National Elec
2、trical Manufacturers Association 1300 North 17th Street, Suite 1752 Rosslyn, Virginia 22209 www.nema.org Copyright 2005 by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention
3、 for the Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions. Copyright 2005 by the National Electrical Manufacturers Association. NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of person
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5、uideline 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 adm
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13、er or maker of the statement. WC 52-2005 Page i Copyright 2005 by the National Electrical Manufacturers Association. CONTENTS Page Foreword ii Adoption Notice .iii Scope.iv Section 1 TEST EQUIPMENT . 1 1.1 Electrode 1 1.2 Wave Form 1 1.3 Voltmeter . 1 1.4 Capacitive Regulation 1 1.5 Failure Detectio
14、n Circuit 1 Section 2 TEST PROCEDURE . 2 2.1 Set-up 2 2.2 Fault Identification . 2 2.3 Calibration . 2 2.4 Operation of Test Voltage Generator (Quick Check Method). 2 WC 52-2005 Page ii Copyright 2005 by the National Electrical Manufacturers Association. Foreword In the preparation of this Standards
15、 Publication input of users and other interested parties has been sought and evaluated. Inquiries, comments, and proposed or recommended revisions should be submitted to the concerned NEMA product Subdivision by contacting the: Vice President, Technical Services National Electrical Manufacturers Ass
16、ociation 1300 North 17th Street, Suite 1752 Rosslyn, Virginia 22209 At the time of the reaffirmation of this standard in 2005, the members of the NEMA High Performance Wire and Cable Section were: AFC Cable Systems New Bedford, MA AmerCable El Dorado, AR American Insulated Wire Corporation Pawtucket
17、, RI Belden CDT, Inc. Richmond, IN Berk-Tek a Nexans Company Elm City, NC Cable USA, Inc. Naples, FL Coleman Cable Inc. Waukegan, IL Draka Comteq USA Inc. Franklin, MA Fisk Alloy Conductors, Inc. Hawthorne, NJ General Cable Highland Heights, KY Harbour Industries, Inc. Shelburne, VT Judd Wire, Inc.
18、Turners Falls, MA Kaneka High-Tech Materials, Inc. Pasadena, TX Leoni Wire, Inc. Chicopee, MA Leviton Manufacturing Co., Inc. Gardena, CA Phelps Dodge High Performance Conductors Inman, SC Quirk Wire Company, Inc. West Brookfield, MA Radix Wire Company Euclid, OH Rea Magnet Wire Company, Inc. Fort W
19、ayne, IN Rockbestos-Surprenant Cable Corporation East Granby, CT Southwire Company Carrollton, GA Specialty Cable Corporation Wallingford, CT The Okonite Company Ramsey, NJ Tyco Electronics/Raychem Wire distribution is unlimited. WC 52-2005 Page iv Copyright 2005 by the National Electrical Manufactu
20、rers Association. Scope This procedure is intended for the dielectric testing of insulation of unshielded single conductor wires. This procedure is not intended for use with multi-conductor cable. WC 52-2005 Page 1 Copyright 2005 by the National Electrical Manufacturers Association. Section 1 TEST E
21、QUIPMENT 1.1 ELECTRODE The electrode shall be of a bead chain construction that will give intimate metallic contact with practically all of the wire insulation surface. The electrode length shall be chosen so that, at the speed being used, the wire will be subjected to no less than 3 nor more than 1
22、00 pulses at any given cross section. 1.2 WAVE FORM The wave-form of the voltage applied to the electrode shall consist of a negative pulse followed by a damped oscillation. The negative pulse shall have a maximum 0 to 90% rise time of 75 s. The repetition rate shall be between 200 and 250 pulses pe
23、r second. The specified voltage shall be defined as the peak magnitude of the initial negative pulse. The peak value of the first positive overshoot and each of the following damped oscillations shall be smaller than the initial negative pulse. The wave form shall be analyzed to determine how long e
24、ach pulse and the following damped oscillations (both positive and negative) remain at an absolute potential of 80% or greater of the initial negative peak. This time duration shall be between 20 and 100 s. The dampening shall be such that the oscillations will be reduced to less than 1% of the peak
25、 voltage before the next pulse starts. The wave-form measurement shall be made without the use of a coupling capacitor. The peak and root means square (rms) voltages shall be measured with a wire of typical design located in the electrode and its conductor grounded. 1.3 VOLTMETER A voltmeter measuri
26、ng the peak voltage of the initial negative pulse at the electrode shall continually indicate the electrode potential. The full-scale meter reading shall be not greater than 15 peak kV. The meter accuracy shall be such that, when the voltage is adjusted to any specified value as measured by the inst
27、rument voltmeter, the actual electrode value will be within 4% of the indicated voltage. 1.4 CAPACITIVE REGULATION The indicated voltage shall decrease no more than 12% when a capacitive load connected between the electrode and ground is increased from an initial value of 12.5 to 25 pF/ in. of elect
28、rode length. 1.5 FAILURE DETECTION CIRCUIT There shall be a fault-indicating circuit that will give a visible or audible indication of a dielectric failure so that the wire can be stopped or suitably identified. The system shall be sufficiently sensitive so that a fault can be detected at 75% of the
29、 selected test voltage when the electrode is arced to ground through a 20 k resistance. The unit shall also be capable of detecting a fault that lasts for the duration of only one impulse. WC 52-2005 Page 2 Copyright 2005 by the National Electrical Manufacturers Association. Section 2 TEST PROCEDURE
30、 2.1 SET-UP The insulated wire shall be threaded through the electrode head and the conductor grounded at one or both ends. With the electrode head energized to the specified voltage, the wire shall pass from the payoff spool through the electrode and on to the take-up spool. The voltage shall be ad
31、justed with the wire in the electrode. 2.2 FAULT IDENTIFICATION If any dielectric failures occur, they shall be cut out or suitably identified for subsequent removal, along with at least 2 in. of wire on each side of the fault. The equipment shall be so wired as to automatically de-energize the high
32、 voltage when the wire is stopped. During the string-up of a new length, every attempt shall be made to expose the entire length, including ends, to the specified voltage. Any ends not tested shall be clearly marked and removed subsequent to this test. A test of dielectric integrity will not be cons
33、idered valid unless the electrical continuity of each tested length of insulated conductor is verified. 2.3 CALIBRATION The instrument voltmeter and wave form shall be checked for compliance with these standards at each intended operating voltage by means of a calibrated oscilloscope connected to th
34、e bead electrode in conjunction with a suitable compensated attenuator. The peak magnitude of the initial negative pulse, the 0 to 90% rise time (first transition duration), the pulse duration at and above the 80% peak, the pulse repetition rate, and the capacitive regulation shall all be derived fr
35、om the wave form display. All devices used for calibration shall have traceability to the National Bureau of Standards. 2.4 OPERATION OF TEST VOLTAGE GENERATOR (QUICK CHECK METHOD) As a quick means to check the normal operation of the test voltage generator, the peak and rms voltages may be measured
36、 (using an electrostatic voltmeter with and without peak detecting attachment). The ratio of these voltages should be within 4.5 and 5.5 to 1. If not, careful calibration of the instrument voltmeter with particular attention to the wave shape of the voltage is recommended. NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 1300 NORTH 17TH STREET, SUITE 900 ROSSLYN. VA 22209www.NEMA.orgTO ORDER ADDITIONAL NEMA STANDARDS VISITWWW.GLOBAL.IHS.COM OR CALL 1-800-854-7179/1-303-397-79565612_0514TB
