1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 2748 Arcing Fault Quenching Equipment STANDARD FOR SAFETYUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRIGHTED MATERIAL NOT
2、 AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Arcing Fault Quenching Equipment, UL 2748 First Edition, Dated September 22, 2017 SUMMARY OF TOPICS This First edition of ANSI/UL 2748, the Standard for Arcing Fault Quenching Equipment, covers
3、 equipment intended to quench arcing faults by creating a lower impedance current path, located within a controlled compartment, to cause the arcing fault to transfer to the new current path. The new requirements are substantially in accordance with Proposal(s) on this subject dated March 17, 2017 a
4、nd July 7, 2017. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form by any means, electronic, mechanical photocopying, recording, or otherwise without prior permission of UL. UL provides this Standard as is without warranty of
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8、oring an electronic Standard on the purchasers computer system. SEPTEMBER 22, 2017 UL 2748 tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL SEPTEMBER 22, 2017 UL 2748 tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTH
9、ER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL SEPTEMBER 22, 2017 1 UL 2748 Standard for Arcing Fault Quenching Equipment Prior to the rst edition, the requirements for the products covered by this standard were included in the Outline of Investigation for Arcing Fault Quenching Equipmen
10、t, UL 2748. First Edition September 22, 2017 This ANSI/UL Standard for Safety consists of the First Edition. The most recent designation of ANSI/UL 2748 as an American National Standard (ANSI) occurred on September 22, 2017. ANSI approval for a standard does not include the Cover Page, Transmittal P
11、ages, and Title Page. Comments or proposals for revisions on any part of the Standard may be submitted to UL at any time. Proposals should be submitted via a Proposal Request in ULs On-Line Collaborative Standards Development System (CSDS) at https:/. ULs Standards for Safety are copyrighted by UL.
12、Neither a printed nor electronic copy of a Standard should be altered in any way. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive property of UL. COPYRIGHT 2017 UNDERWRITERS LABORATORIES INC. ANSI/UL 2748-2017UL COPYRIGHTE
13、D MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL SEPTEMBER 22, 2017 ARCING FAULT QUENCHING EQUIPMENT - UL 2748 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTROD
14、UCTION 1 Scope .4 2 Components4 3 Units of Measurement .5 4 Undated References 5 5 Glossary .5 CONSTRUCTION 6 General 6 7 Enclosure 6 8 Primary or Power Carrying Circuits6 9 Grounding7 10 Control and Secondary Wiring .7 11 Creepage and Clearance Distance .7 12 Wiring 8 13 Operation .8 PERFORMANCE 14
15、 General.9 15 Continuous Current Test 9 16 Power-Frequency Withstand Voltage Tests 10 17 Maximum Withstand Current Test.10 18 Internal Arcing Fault Test 11 19 Arc Transfer Test .12 RATINGS 20 General12 MARKING 21 General13 INSTRUCTIONS 22 General14 SEPTEMBER 22, 2017 ARCING FAULT QUENCHING EQUIPMENT
16、 - UL 2748 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scope 1.1 These requirements cover equipment intended to quench arcing faults by creating a lower impedance current path, located within a controlled compartment, to
17、cause the arcing fault to transfer to the new current path. 1.2 These requirements cover equipment that may either be completely enclosed units or intended to be installed within power distribution equipment. 1.3 These requirements cover equipment rated up to 52 kV ac maximum. 1.4 This standard does
18、 not include the requirements for sensors intended to detect arcing faults, devices intended to trigger the functioning of the arc quenching equipment, or devices that are intended to interrupt arcing fault currents. 1.5 This standard does not include all the requirements for integration and testing
19、 of arc quenching equipment within equipment it is intended to protect. 2 Components 2.1 Except as indicated in 2.2, a component of a product covered by this standard shall comply with the requirements for that component. 2.2 A component is not required to comply with a specic requirement that: a) I
20、nvolves a feature or characteristic not required in the application of the component in the product covered by this standard, or b) Is superseded by a requirement in this standard. 2.3 A component shall be used in accordance with its rating established for the intended conditions of use. 2.4 Specic
21、components are incomplete in construction features or restricted in performance capabilities. Such components are intended for use only under limited conditions, such as certain temperatures not exceeding specied limits, and shall be used only under those specic conditions. SEPTEMBER 22, 2017 ARCING
22、 FAULT QUENCHING EQUIPMENT - UL 2748 4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 3 Units of Measurement 3.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information. 4 Undat
23、ed References 4.1 Any undated reference to a code or standard appearing in the requirements of this standard shall be interpreted as referring to the latest edition of that code or standard. 5 Glossary 5.1 For the purpose of this standard, the following denitions apply. 5.2 ARCING FAULT A non-intent
24、ional discharge of electrical energy in air or other gas, including discharges across the surface of an insulating material. 5.3 ARC TRANSFER TIME The interval between triggering of the arc quenching device and the quenching of the arcing fault. 5.4 CONTROLLED COMPARTMENT A portion of equipment, int
25、ended to enclose the new current path when an arcing fault is transferred. This compartment may be provided with openings or aps for pressure relief. 5.5 LOW-VOLTAGE A voltage of 1000 V ac or less. 5.6 MEDIUM-VOLTAGE A voltage of greater than 1000 V ac, up to 52 kV ac. 5.7 POLLUTION DEGREE 2 MICROEN
26、VIRONMENT An area where normally, only nonconductive pollution occurs, but where occasional, temporary conductivity may be expected. Typical constructions that reduce the possibilities of conductive pollution and condensation or high humidity are; a) Un-ventilated enclosures that are provided with c
27、ontinuous application of heat through the use of heaters or through continuous energization of the equipment, with interruptions such that cooling to the point of condensation does not occur or b) The use of ventilated enclosures where all openings are provided with lters. 5.8 QUENCHING DEVICE Equip
28、ment that is used to extinguish or redirect an arcing fault. SEPTEMBER 22, 2017 ARCING FAULT QUENCHING EQUIPMENT - UL 2748 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONSTRUCTION 6 General 6.1 Where referenced in this standard, require
29、ments contained in the Standard for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear, UL 1558, are applicable to low-voltage quenching devices, and the requirements contained in Metal-Enclosed Interrupter Switchgear, IEEE C37.20.3 are applicable to medium-voltage quenching devices. 7 Encl
30、osure 7.1 Other than as noted in 7.2, quenching devices shall comply with the requirements of 7.3 7.6. 7.2 Devices covered by this standard that are intended for installation completely within the enclosure of other equipment need not be provided with an enclosure. 7.3 Low-voltage devices provided w
31、ith complete enclosures shall comply with the enclosure requirements of the Standard for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear, UL 1558. Medium-voltage devices provided with complete enclosures shall comply with the enclosure requirements of Metal-Enclosed Interrupter Switchgea
32、r, IEEE C37.20.3. 7.4 Where a portion of the quenching device is intended to ll or protrude through an opening, or otherwise form a portion of the enclosure of the overall equipment, it shall be investigated in accordance with the enclosure requirements of the standard for the overall equipment. 7.5
33、 Devices described in 7.3 and 7.4 may be assigned one or more enclosure type designations in accordance with 21.10. The devices shall comply with the requirements of the Standard for Enclosure for Electrical Equipment, Environmental Considerations, UL 50E for each assigned type designation when inst
34、alled. 7.6 Gaskets relied upon to maintain the environmental rating of the equipment shall comply with the gasket requirements of the Standard for Enclosure for Electrical Equipment, Environmental Considerations, UL 50E. 8 Primary or Power Carrying Circuits 8.1 Low-voltage equipment shall comply wit
35、h Section 6, Primary or Power Carrying Circuits, of the Standard for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear, UL 1558. 8.2 Medium-voltage equipment shall comply with Section 7.1, Buses and primary connections, of Metal-Enclosed Interrupter Switchgear, IEEE C37.20.3. SEPTEMBER 22,
36、 2017 ARCING FAULT QUENCHING EQUIPMENT - UL 2748 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 9 Grounding 9.1 There shall be provision for grounding all non-current carrying metal parts of the equipment. In addition, the following parts
37、shall be grounded: a) The metal case of a frame or instrument transformer; b) The metal case of an instrument, meter or relay; or c) The secondary circuit of a current or voltage transformer. 9.2 The case of an instrument, relay, meter, or similar device, if mounted on a grounded metal surface and s
38、ecured thereto by means of metal screws, is considered to be grounded. 10 Control and Secondary Wiring 10.1 An insulated conductor provided as part of a control circuit or secondary wiring shall be rated for the particular application and shall have an ampacity not less than the continuous current r
39、ating of the circuit in which it is connected. Where loads are of an intermittent nature, such as in trip and closing circuits, conductors shall be sized to provide their intended function with respect to voltage drop and mechanical strength. 11 Creepage and Clearance Distance 11.1 Section 12, Spaci
40、ngs, of the Standard for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear, UL 1558 applies to the power circuits of low-voltage quenching equipment, other than as noted in 11.3. 11.2 No minimum creepage or clearance distances are specied for medium-voltage circuits in quenching equipment,
41、 other than distances sufficient to meet the dielectric requirements specied in this standard for the voltage rating of the equipment. 11.3 No minimum creepage or clearance distances are specied across the contacts of the quenching means when these contacts are contained within a pollution degree 2
42、microenvironment, and the quenching equipment meets the dielectric test requirements of this standard with the quenching device in the open position. 11.4 Creepage and clearance distances within low-voltage control circuits of quenching devices shall comply with the creepage and clearance distance r
43、equirements of the Standard for Industrial Control Equipment, UL 508 or the Standard for Low-Voltage Switchgear and Controlgear Part 1: General rules, UL 60947-1. Creepage and clearance distances between low-voltage control circuits and medium-voltage circuits shall be no smaller than the creepage a
44、nd clearance distances required from the medium-voltage circuit to grounded metal, and shall also be sufficient to meet the dielectric requirements specied in this standard for the maximum voltage rating of the equipment, with the control circuits grounded during testing. SEPTEMBER 22, 2017 ARCING F
45、AULT QUENCHING EQUIPMENT - UL 2748 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 11.5 The pollution degree 2 microenvironment specied in 11.3 need not be maintained during or after the quenching of an arcing fault if servicing of the quen
46、ching means is required after an arcing fault event, and the quenching means is marked in accordance with 21.5. 11.6 For printed wiring boards, the creepage and clearance distances shall comply with requirements of the Standard for Insulation Coordination Including Clearance and Creepage Distances f
47、or Electrical Equipment, UL 840. For the purpose of determining required creepage and clearance distances, quenching devices shall be considered to be located within circuits of overvoltage category 3. All quenching devices are considered to be installed in pollution degree 3 environments, except fo
48、r portions of the device located in a pollution degree 2 microenvironment. 11.7 Pollution Degree 2 shall be considered to exist on a printed-wiring board where a coating provides an uninterrupted covering of the conductive material for at least one of two conductive materials and covers the entire s
49、pace between the two conductive materials for which the spacing is being evaluated. 12 Wiring 12.1 Insulated conductors provided as part of a quenching device shall be rated for the particular application and shall have an ampacity no less than the maximum current rating of the circuit to which they are connected. 12.2 Wiring shall be located or protected to prevent contact with any sharp edge or moving part that could damage the insulation. 12.3 Insulated conductors shall be separated from wiring and uninsula
