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1、Subject 635 (197, 250, 471, 507, 745, 859, 923, 998, 1017, 1026, 1082, 1083, 1240, 1363, 1431, 1727, 2157, 2158, and 60950) (in reply, refer to Subject 635) TO: 1655 Scott Blvd. Santa Clara, CA 95050 September 27, 2004 Subscribers to ULs Standards Services for Insulating Bushings Commercial Electric
2、 Cooking Appliances Commercial Electric Personal Grooming Appliances Commercial Refrigerators and Freezers Electric Clothes Dryers Electric Clothes Washing Machines and Extractors Electric Commercial Clothes Drying Equipment Electric Fans Electric Household Cooking and Food Serving Appliances Househ
3、old Electric Coffee Makers and Brewing-Type Appliances Household Electric Personal Grooming Appliances Household Electric Skillets and Frying-Type Appliances Household Refrigerators and Freezers Humidifiers Information Technology Equipment Microwave Cooking Appliances Personal Hygiene and Health Car
4、e Appliances Portable Electric Tools Relocatable Power Taps Vacuum Cleaners, Blower Cleaners, and Household Floor Finishing Machines SUBJECT: Request for Comments on Proposed Requirements for the Second Edition of the Standard for Insulating Bushings, UL 635 PROPOSED EFFECTIVE DATE SUMMARY OF TOPICS
5、 This bulletin proposes the following changes in requirements: 1. Revision of the Scope by listing additional products that are not covered by the requirements of UL 635 2. Addition of requirements for flammability, temperature ratings, materials substitution, and molding considerations to Materials
6、, Section 5. 3. Clarify requirements for conditioning strain relief bushings during the Strain Relief Test. 4. Clarify the requirements for the Humidity Test. 5. Clarify the requirements for conducting the Elevated Temperature Test. COMMENTS DUE: November 22,2004 Copyright Underwriters Laboratories
7、Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/30/2006 04:15:38 MDTNo reproduction or networking permitted without license from IHS -,-,- SUBJECT 635 -2- SEPTEMBER 27,2004 Attached as Appendix A for your review and comment are proposed require
8、ments for UL 635. Attached as Appendix B for your review and comment are the impact statements and proposed effective date. Questions regarding interpretation of requirements should be directed to the responsible UL Staff. Please note that proposed requirements are of a tentative and early nature an
9、d are for review and comment only. Current requirements are to be used to judge a product until these requirements are published in final form. PRODUCTSANDINDUSTRIESAFFECTED BYTHE PROPOSAL UL requests your assistance in identifying other products or industries that might be affected by the requireme
10、nts contained in this bulletin. UL suggests that all suppliers or customers for these products and industries be made aware of these requirements prior to their proposed effective date. Also, please forward your suggestions to UL so that these products and industries may be identified in future bu I
11、 let ins. Comments should be made in writing and may be sent by fax to (408) 556-6045 or by mail to the attention of Derrick L. C. Martin at ULs Santa Clara office. Comments may also be sent via E-mail to Derrick.L.M. Please reference all correspondence to Subject 635. Note all comments received are
12、 public and may be circulated to others. If you respond by fax or E-mail, please include your full name and company name and address to ensure a reply. Unless specifically requested to do so, UL will not acknowledge comments indicating concurrence with these proposals. UNDERWRITERS LABORATORIES INC.
13、 REVIEWED BY: DERRICK L. C. MARTIN Project Manager Engineering Associate Standards Department SANTA CLARA OFFICE Phone: (408) 876-2565 Fax: (408) 556-6045 E-mail: Derrick.L.M http:/ TOM MAYERHOFER Principal Engineer - Electrical Insulation Systems and Materials NORTH BROOK OFF ICE Phone: (847) 664-2
14、903 Fax: (847) 313-2903 E-mail: Thomas.L.M Copyright O 2004 Underwriters Laboratories Inc. SR: RKM bul-635.2-20040927 Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/30/2006 04:15:38 MDTNo reproduction or net
15、working permitted without license from IHS -,-,- SUBJECT 635 -Al- SEPTEMBER 27,2004 APPENDIX A PROPOSED REQUIREMENTS FOR THE SECOND EDITION OF THE STANDARD FOR INSULATING BUSHINGS, UL 635 For your convenience in review, proposed additions to existing requirements are shown underlined and proposed de
16、letions are shown +me - 2. Insulatina bus hinas; - 3. Liauid-tiaht flexible cord fittinas; 0 Mesh arbs; - 5. Strain relief arbs; 6 Strain relief arbs for bus d rot) cab les; - 7. Strain relief arbs for flexible cords: and - 8. Strain relief with wire mesh cord arbs. 2. MATERIALS RATIONALE UL propose
17、s to reorganize the format of Section 5 by adding subsections for requirements for flammability, temperature ratings, materials substitution, and molding considerations. The intent of the proposal is to provide clarity to the current material requirements in UL 635. In addition, the proposal would c
18、larify the material substitution requirements as well as the extent to which the materials may or may not be modified during the molding process. The proposed revision of Section 5 includes the following changes: 1. Paragraphs 5.1, 5.3, and 5.4 have been re-designated as Paragraphs 5.1.1, 5.1.2, and
19、 5.1.3 respectively. The proposed Paragraphs 5.1 .I, 5.1.2, and 5.1.3 have been transferred to the proposed Subsection 5.1, titled “General.” 2. Paragraph 5.2 has been revised to include a reference to the IEC Standard for Test Flames - 50 W Horizontal and Vertical Flame Test Methods, 60695-11-10. P
20、aragraph 5.2 has been re-designated as Paragraph 5.2.2 and has been transferred to the proposed Subsection 5.2, titled “Flammability.” 3. The proposed temperature rating requirements would appear in UL 635 as Subsection 5.3; the proposed requirements for materials substitution would appear in the st
21、andard as Subsection 5.4, and the proposed requirements for molding considerations would appear in the standard as Subsection 5.5. The proposed requirements in Paragraph 5.2.1 and Subsections 5.3 - 5.5 are based on requirements from the Standard for Positioning Devices, UL 1565. UL determined that S
22、tandard UL 1565 was the most appropriate source for the proposed requirements because, like bushings, positioning devices are typically made from similar polymeric materials that are mechanically relied upon to maintain the relative position of insulated wires. PROPOSAL (CURRENT VERSION OF SECTION 5
23、) Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./7838506130 Not for Resale, 08/30/2006 04:15:38 MDTNo reproduction or networking permitted without license from IHS -,-,- SUBJECT 635 -A3- SEPTEMBER 27,2004 5 Materials 5.1 Ceramic material
24、s and some molded compositions such as phenolic and urea formaldehyde are capable of being used as materials for a separate insulating bushing. Vulcanized fiber is not prohibited from being used when the bushing is not less than 3/64 inch (1.2 mm) thick, and when it is formed and secured in place so
25、 that it is not adversely affected by conditions of typical moisture. Other materials, such as nylon, are capable of being used after a suitable investigation. See Humidity Test, Section 11, and Elevated Temperature Test, Section 12. 5.2 Materials employed in the construction of insulating bushings
26、shall be classified with a flammability rating of at least 94 HB as determined by the Standard for Safety for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL 94. 5.3 Wood, hot-molded shellac, tar compositions, or rubber are not to be used as materials for a separa
27、te insulating bushing. 5.4 The wall thickness of an insulating bushing shall not be less than 3/64 inch (1.2 mm) unless a thickness has been determined to be capable of being used as a result of an investigation (see reference to vulcanized fiber in 5.1). This requirement does not preclude the use o
28、f narrow slots or openings in the wall of an insulating bushing when the intended cable, flexible cord, or insulated wire is not capable of being pressed into such slots or openings. (PROPOSED VERSION OF SECTION 5) 5 Materials 5.1 General 5.1.1 Ceramic materials and some molded compositions such as
29、phenolic and urea formaldehyde are capable of being used as materials for a separate insulating bushing. Vulcanized fiber is not prohibited from being used when the bushing is not less than 3/64 inch (1.2 mm) thick, and when it is formed and secured in place so that it is not adversely affected by c
30、onditions of typical moisture. Other materials, such as nylon, are capable of being used after a suitable investigation. See Humidity Test, Section 11, and Elevated Temperature Test, Section 12. 5.1.2 Wood, hot-molded shellac, tar compositions, or rubber shall not to be used as materials for a separ
31、ate insulating bushing. 5.1.3 The wall thickness of an insulating bushing shall not be less than 3/64 inch (1.2 mm) unless a thickness has been determined to be capable of being used as a result of an investigation. See reference to vulcanized fiber in 5.1 .I. This requirement does not preclude the
32、use of narrow slots or openings in the wall of an insulating bushing when the intended cable, flexible cord, or insulated wire is not capable of being pressed into such slots or openings. Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwestern Div./78
33、38506130 Not for Resale, 08/30/2006 04:15:38 MDTNo reproduction or networking permitted without license from IHS -,-,- SUBJECT 635 -A4- SEPTEMBER 27,2004 5.2 Flammability 5.2.1 Materials employed in the construction of insulating bushings shall be classified with a flammability rating of at least HB
34、 as determined by the Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL 94 or IEC 60695-1 1-10, Test Flames - 50 W Horizontal and Vertical Flame Test Methods. 5.3 Temperature Rating 5.3.1 The temperature rating of the device, as indicated in 10.1, 12.3,
35、 and 15.4, is to be based on the mechanical-without-impact relative thermal index (RTI - Strength) of the material used in the device. The relative thermal index shall be determined in accordance with the Standard for Polymeric Materials - Long Term Property Evaluations, UL 746B. Note: The relative
36、thermal index of a material is an indication of the materials ability to retain a particular property (such as physical or electrical) when exposed to an elevated temperature for an extended period of time. For each material, a number of relative thermal indices are established, each related to a sp
37、ecific property, and specific thickness of the material. 5.3.2 The temperature rating of a polymeric device shall not exceed the relative thermal index of the material that is selected for the device, in the devices minimum critical thickness. 5.4 Substitution of Materials 5.4.1 Another polymeric ma
38、terial shall be allowed to be substituted in a device having met the requirements of this Standard only when all of the following conditions are met and compliance is determined through appropriate investigation: a) There is an identical generic description (for example: Type 66, 30 percent glass fi
39、lled, FR type, polyamide). b) Tensile strength of materials, determined in accordance with the Standard for Polymeric Materials - Short Term Property Evaluations, UL 746A or IS0 527-1, Plastics - Determination of Tensile Properties - Part 1 : General Principles, and IS0 527-2, Plastics - Determinati
40、on of Tensile Properties - Part 2: Test Conditions for Moulding and Extrusion Plastics, shall be compared, and shall indicate that the substitute material has a strength of at least 95 percent of that of the original material. The tensile strengths used in this comparison shall be generated by eithe
41、r: 1) A previous investigation or 2) Side-by-side testing of both materials. c) The materials relative thermal indices shall be used for the temperature rating of the device as specified in 5.3.1. Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=Army Northwester
42、n Div./7838506130 Not for Resale, 08/30/2006 04:15:38 MDTNo reproduction or networking permitted without license from IHS -,-,- SUBJECT 635 -A5- SEPTEMBER 27,2004 5.5 Molding Considerations 5.5.1 Except as indicated in (a) and (b), polymeric materials used to mold or fabricate devices covered by thi
43、s Standard shall be made from materials that are 100 percent virgin and unmodified by the molder: a) Devices made from thermoplastic materials are limited to 25 percent regrind by weight of the same material, unless the results of a separate investigation indicate acceptable performance for the mate
44、rial or the specific device. The Standard for Polymeric Materials - Fabricated Parts, UL 746D, includes guidelines to be considered in such a separate investigation. b) Devices covered by this Standard shall be allowed to employ colorants, flame retardants, fillers, mold-release lubricants, color co
45、ncentrates, dyestuff, chemical blowing agents or reinforcements in conjunction with the polymeric material, when the additive or concentrate is tested and found not to adversely affect the critical properties of the material. An additive or concentrate of unknown performance shall not be used. The S
46、tandard for Polymeric Materials - Fabricated Parts, UL 746D, provides guidance for the use of specific additives that may be used in the molding process without need for separate investigation. 5.5.2 Devices shall not employ materials that have been blended together unless one of the following condi
47、tions have been met: a) When two materials have already been individually considered acceptable for an application, and are both found to be generically similar, are both produced by the same manufacturer, and are both designated HB in the minimum part thickness when tested in accordance with the St
48、andard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL 94 or IEC 60695-11-10, Test Flames - 50 W Horizontal and Vertical Flame Test Methods, these materials may be dry blended in any proportion by the manufacturer without further testing. b) When two materials
49、 have already been individually considered acceptable for an application and are both found to be generically similar, are both produced by the same manufacturer, each is designated V-O, V-I, or V-2 in the minimum part thickness when tested in accordance with the Standard for Tests for Flammability of Plastic Mate