ANSI UL 1876-2015 UL Standard for Safety Isolating Signal and Feedback Transformers for Use in Electronic Equipment (Fourth Edition Reprint with Revisions Through and Including Sep.pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 1876 Isolating Signal and Feedback Transformers for Use in Electronic EquipmentUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL CO

2、PYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Isolating Signal and Feedback Transformers for Use in Electronic Equipment, UL 1876 Fourth Edition, Dated June 25, 2015 Summary of Topics This revision of UL 1876 is being

3、 issued to reaffirm approval as an American National Standard. No changes in requirements are involved. The revisions are substantially in accordance with Proposal(s) on this subject dated July 17, 2015. Text that has been changed in any manner or impacted by ULs electronic publishing system is mark

4、ed with a vertical line in the margin. 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

5、is without warranty of any kind, either expressed or implied, including but not limited to, the implied warranties of merchantability or tness for any purpose. In no event will UL be liable for any special, incidental, consequential, indirect or similar damages, including loss of prots, lost savings

6、, loss of data, or any other damages arising out of the use of or the inability to use this Standard, even if UL or an authorized UL representative has been advised of the possibility of such damage. In no event shall ULs liability for any damage ever exceed the price paid for this Standard, regardl

7、ess of the form of the claim. Users of the electronic versions of ULs Standards for Safety agree to defend, indemnify, and hold UL harmless from and against any loss, expense, liability, damage, claim, or judgment (including reasonable attorneys fees) resulting from any error or deviation introduced

8、 while purchaser is storing an electronic Standard on the purchasers computer system. SEPTEMBER 16, 2015 UL 1876 tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL SEPTEMBER 16, 2015 UL 1876 tr2 No Text on This PageUL COPYRIGHTED MATERIAL NO

9、T AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL JUNE 25, 2015 (Title Page Reprinted: September 16, 2015) 1 UL 1876 Standard for Isolating Signal and Feedback Transformers for Use in Electronic Equipment First Edition September, 1989 Second Edition September, 1995 Thi

10、rd Edition May, 2001 Fourth Edition June 25, 2015 This ANSI/UL Standard for Safety consists of the Fourth Edition including revisions through September 16, 2015. The most recent designation of ANSI/UL 1876 as an American National Standard (ANSI) occurred on September 14, 2015. ANSI approval for a st

11、andard does not include the Cover Page, Transmittal Pages and Title Page. Any other portions of this ANSI/UL standard that were not processed in accordance with ANSI/UL requirements are noted at the beginning of the impacted sections. Comments or proposals for revisions on any part of the Standard m

12、ay 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 http:/. ULs Standards for Safety are copyrighted by UL. Neither a printed nor electronic copy of a Standard should be altered in any way. All of

13、 ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive property of UL. COPYRIGHT 2015 UNDERWRITERS LABORATORIES INC. ANSI/UL 1876-2011 (R2015)UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMI

14、SSION FROM UL JUNE 25, 2015 UL 1876 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .4 2 Components 4 3 Units of Measurement .4 4 Undated References 5 5 Glossary .5 CONSTRUCTION 6 Housing 6

15、 7 Resistance to Corrosion .6 8 Mechanical Assembly .6 9 Impregnation .7 10 Leads 7 10.1 Insulation .7 10.2 Connections between leads 7 10.3 Strain relief .7 10.4 Protection of wiring 7 11 Terminal Support 8 12 Transformer Insulation 8 13 Spacings 12 14 Double Protection .12 PERFORMANCE 15 General 1

16、2 16 Transformer Dielectric Voltage-Withstand Test .13 17 Strain Relief Test .14 18 Insulation Resistance Test .14 19 Thermoplastic Bobbin Temperature Stability Test .14 20 Insulating Materials Equivalence Test .15 21 Insulating System Tests .16 21.1 General .16 21.2 Conditioning .17 21.3 Dielectric

17、 voltage-withstand 17 21.4 Voltage surge 17 MANUFACTURING AND PRODUCTION TEST 22 Dielectric Voltage-Withstand Test .19 MARKINGS 23 General 22 APPENDIX A Standards for ComponentsA1 JUNE 25, 2015 UL 1876 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSIO

18、N FROM UL INTRODUCTION 1 Scope 1.1 These requirements apply to isolating signal and feedback transformers intended to be used in electronic equipment where only audio, video, and other signal waveforms are transformed. These transformers are intended to provide isolation from circuits that are eithe

19、r conductively connected to a branch circuit supply or connected to secondary circuits involving voltages that are considered to present a risk of electric shock by the nature of their use in an end-product. 1.2 These requirements do not apply to transformers and motor-transformers that are connecte

20、d to a supply circuit to power a secondary circuit. 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. See Appendix A for a list of standards covering components used in the products covered by this st

21、andard. 2.2 A component is not required to comply with a specic requirement that: a) Involves 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

22、accordance with its rating established for the intended conditions of use. 2.4 Specic 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 l

23、imits, and shall be used only under those specic conditions. 3 Units of Measurement 3.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information. 3.2 Unless otherwise indicated, all voltage and current values mentioned in this standard a

24、re root-mean-square (rms). JUNE 25, 2015 UL 1876 4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 4 Undated References 4.1 Any undated reference to a code or standard appearing in the requirements of this standard shall be interpreted as ref

25、erring 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 ENCAPSULATION COMPOUND A material, generally of the polymeric type, that is at least 1/32 inch (0.8 mm) thick and that encapsulates the transformer by being molde

26、d around the coil windings where the transformer is not provided with any other housing material. 5.3 HAZARDOUS CIRCUIT A circuit in an appliance that either is conductively connected to a branch circuit or involves a risk of electric shock. 5.4 HAZARDOUS CIRCUIT WINDING A winding of an isolating si

27、gnal transformer that is intended to be connected to a hazardous circuit. 5.5 HOUSING A partial or complete enclosure, generally of polymeric material or metal, that is around the outside of all or part of the transformer (such as end bells) but is not in contact with current-carrying parts. 5.6 IMP

28、REGNATION COMPOUND A material, generally of the polymeric type and commonly in the form of varnish, that is absorbed by insulating materials such as electrical grade paper and that provides a coating of less than 1/32 inch (0.8 mm) thick over all transformer parts. 5.7 ISOLATED CIRCUIT A circuit tha

29、t is not conductively connected to the supply circuit. 5.8 ISOLATED WINDING A winding of an isolating signal transformer that is intended to be connected to a nonhazardous circuit. 5.9 POTTING COMPOUND A material, generally of the polymeric type, that seals the transformer by lling the space between

30、 the coil windings and the housing. Potting material differs from impregnation material in that impregnation material is not intended to completely ll the space between the coil windings and the housing. 5.10 TRANSFORMER FAMILY A series of transformer models which have identical insulating materials

31、 provided between each winding. The number of windings may vary for different models in a family, but the models must either all be suitable for securement to a live chassis or not suitable for securement to a live chassis. 5.11 WINDING A coil of wire including the start, nish, and crossover leads u

32、p to the point where insulated leads or terminals are connected. JUNE 25, 2015 UL 1876 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONSTRUCTION 6 Housing 6.1 A material provided as a housing around all or part of a transformer shall com

33、ply with 6.2 if of metal and 6.3 if of polymeric material. 6.2 Sheet metal provided around all or a portion of the current-carrying parts of a transformer shall be at least 0.010 inch (0.25 mm) thick if formed of steel and 0.020 inch (0.51 mm) thick if formed of aluminum or copper alloy. Exception:

34、A metal housing is not required to be of a specic minimum thickness if spacings are maintained by a potting compound complying with 6.3. 6.3 A polymeric material provided to encapsulate, pot, or house a transformer shall be rated V-2 or better in accordance with the Standard for Tests for Flammabili

35、ty of Plastic Materials for Parts in Devices and Appliances, UL 94. Exception: A polymeric material less than 1/16 inch (1.6 mm) thick need not be rated V-2 or better if the material is rated V-2 or better for a thickness of 1/16 inch. 7 Resistance to Corrosion 7.1 All ferrous parts shall be provide

36、d with a means for corrosion resistance. 8 Mechanical Assembly 8.1 A transformer shall be formed and assembled so that it has the strength and rigidity necessary to resist the abuses to which it is likely to be subjected. The risk of re, electric shock, and injury to persons due to total or partial

37、collapse with resulting reduction of spacings, loosening or displacement of parts, or the like shall not be increased when the component is subjected to such likely abuse. 8.2 An adhesive used in the assembly of an enclosure shall be investigated as specied in the Standard for Polymeric Materials Us

38、e in Electrical Equipment Evaluations, UL 746C. Methods utilizing fusion techniques, such as solvent bonding, ultrasonic welding, electromagnetic induction, and thermal welding, need not be investigated. JUNE 25, 2015 UL 1876 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRI

39、BUTION WITHOUT PERMISSION FROM UL 9 Impregnation 9.1 A transformer shall be impregnated unless it is either potted or encapsulated, or the absorptive insulating materials such as ber, paper, and the like are individually impregnated, treated, or the like. 10 Leads 10.1 Insulation 10.1.1 The insulati

40、on on lead wires, sleeving, and tubing shall be rated for the voltage involved and shall be ame rated VW-1. 10.1.2 Insulating tape used on lead wires shall be rated ame-retardant and rated for the voltage involved. 10.2 Connections between leads 10.2.1 Connections shall be soldered, welded, or other

41、wise positively secured. A soldered connection shall be made mechanically secure before soldering. 10.3 Strain relief 10.3.1 Strain relief shall be provided so that stress on each individual lead is not transmitted to connections as determined by the Strain Relief Test, Section 17. 10.3.2 Strain rel

42、ief that depends solely on potting compound or encapsulation material shall be constructed such that mechanical securement is provided by the routing of lead wires, such as right angle turns in the leads as they pass through the material or compound, or by a knot in the leads. 10.4 Protection of wir

43、ing 10.4.1 The edges of an opening through which wires pass shall be free of burrs, ns, and other defects that tend to damage the conductor insulation and, if sheet metal, shall be rolled or covered by a bushing complying with 10.4.2. 10.4.2 A bushing that is relied upon for protection of wiring sha

44、ll be: a) Secured in place by mechanical means other than friction alone; b) Made of material other than natural rubber; and c) Of a construction that does not cause wire damage. JUNE 25, 2015 UL 1876 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION

45、 FROM UL 11 Terminal Support 11.1 A polymeric material that directly supports terminals and is not provided as layers of coil insulation shall be: a) Rated for temperatures of at least 105C (221F) and have a ammability rating of V-2 or better for the minimum material thickness provided or 1/16 inch

46、(1.6 mm), whichever is greater. b) Suitable for direct support of live parts with respect to hot-wire ignition, high-current-arc resistance to ignition, volume resistivity, and dielectric strength in accordance with the Standard for Polymeric Materials Use in Electrical Equipment Evaluations, UL 746

47、C. Exception No. 1: A polymeric material that supports only the isolated winding terminals need not comply with (b). Exception No. 2: A polymeric material subjected to the following need not to comply with the volume resistivity and dielectric strength requirements specied in (b). a) An additional d

48、ielectric voltage-withstand test conducted between adjacent hazardous circuit terminals on the transformer following the method and complying with the requirements described in the Transformer Dielectric Voltage-Withstand Test, Section 16; and b) Insulation resistance between adjacent hazardous circ

49、uit terminals with windings disconnected, in addition to those described in the Insulation Resistance Test, Section 18, that is found to be greater than 10 megohms; 12 Transformer Insulation 12.1 Insulation (excluding the magnet wire coating) between the parts specied below shall comply with 12.4 and with either the generic insulation material types and thicknesses specied in 12.5 or with the Insulating Materials Equivalence Test, Section 20 a) Hazardous circuit windings and dead-metal parts