1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 551 Transformer-Type Arc-Welding MachinesUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR
2、FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Transformer-Type Arc-Welding Machines, UL 551 Eighth Edition, Dated April 24, 2009 Summary of Topics This revision to UL 551 is being issued to remove the reference to the withdrawal date of UL 873 and to addr
3、ess universal upkeep of UL Standards for Safety. These revisions are considered to be non-substantive and not subject to ULs STP process. Text that has been changed in any manner or impacted by ULs electronic publishing system is marked with a vertical line in the margin. Changes in requirements are
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8、st any loss, expense, liability, damage, claim, or judgment (including reasonable attorneys fees) resulting from any error or deviation introduced while purchaser is storing an electronic Standard on the purchasers computer system. The requirements in this Standard are now in effect, except for thos
9、e paragraphs, sections, tables, gures, and/or other elements of the Standard having future effective dates as indicated in the note following the affected item. The prior text for requirements that have been revised and that have a future effective date are located after the Standard, and are preced
10、ed by a SUPERSEDED REQUIREMENTS notice. NOVEMBER 19, 2013 UL 551 tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL NOVEMBER 19, 2013 UL 551 tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUT
11、ION WITHOUT PERMISSION FROM UL APRIL 24, 2009 (Title Page Reprinted: November 19, 2013) 1 UL 551 Standard for Transformer-Type Arc-Welding Machines First Edition September, 1937 Second Edition October, 1952 Third Edition April, 1972 Fourth Edition July, 1977 Fifth Edition May, 1981 Sixth Edition Jan
12、uary, 1987 Seventh Edition January, 1994 Eighth Edition April 24, 2009 This ANSI/UL Standard for Safety consists of the Eighth Edition including revisions through November 19, 2013. The most recent designation of ANSI/UL 551 as a Reaffirmed American National Standard (ANS) occurred on October 29, 20
13、13. ANSI approval for a standard does not include the Cover Page, Transmittal Pages, Title Page, or effective date information. 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 Coll
14、aborative 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 ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole a
15、nd exclusive property of UL. COPYRIGHT 2013 UNDERWRITERS LABORATORIES INC. ANSI/UL 551-2009 (R2013)UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL APRIL 24, 2009 TRANSFORMER-TYPE ARC-WELDING MACHINES - UL 551 2 No Text on This PageUL COPYRIG
16、HTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .5 2 Components 5 3 Units of Measurement .5 4 References .6 5 Terminology 6 CONSTRUCTION 6 General 6 7 Frame and Enclosure 6 8 Accessibility of Live Parts .10 9 Protection A
17、gainst Corrosion 11 10 Supply Connections .11 10.1 General .11 10.2 Cords and plugs .12 10.3 Strain relief, bushings, and entrance holes 13 10.4 Wiring terminals and leads 14 11 Wire-Bending Space 16 12 Grounding .19 13 Spacings 20 14 Mechanical Assembly .22 15 Internal Wiring 22 16 Current-Carrying
18、 Parts 23 17 Electrical Insulating Materials .23 18 Capacitors .24 19 Fans 24 20 Overload Protection .25 21 Receptacles 26 22 Switches and Control Devices 26 23 Transformers .27 PERFORMANCE 24 General 27 25 Leakage Current Test .28 26 Leakage Current Test Following Humidity Conditioning 30 27 Output
19、 Test 31 27.1 Open-circuit voltage 31 27.2 Rated current 31 27.3 Secondary current 31 28 Input Test 32 29 Short-Circuit Current Test 32 30 Temperature Test .33 31 Dielectric Voltage-Withstand Test .36 32 Overload Test on Switches and Controls 37 33 Endurance Test on Switches and Controls .37 34 Diel
20、ectric Voltage-Withstand Test on Switches and Controls .38 35 Short Circuit Test on Capacitors 38 APRIL 24, 2009 TRANSFORMER-TYPE ARC-WELDING MACHINES - UL 551 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 36 Abnormal Operation Test 39 37
21、 Stalled Fan Abnormal Operation Test .39 38 Compression and Torsion Tests 40 38.1 General .40 38.2 Compression test .40 38.3 Torsion test 40 39 Strain Relief Test .40 40 Permanence of Marking .41 40.1 General .41 40.2 Oven-aging test 41 40.3 Immersion Test 42 40.4 Standard-atmosphere test .42 40.5 U
22、nusual-condition exposure test .42 MANUFACTURING AND PRODUCTION TESTS 41 Grounding Continuity 42 RATING 42 Details .43 MARKING 43 Details .44 INSTRUCTIONS 44 Instruction Manual 47 APPENDIX A Standards for ComponentsA1 APRIL 24, 2009 TRANSFORMER-TYPE ARC-WELDING MACHINES - UL 551 4UL COPYRIGHTED MATE
23、RIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scope 1.1 These requirements cover limited duty welding and cutting power sources, wire feeders, torches, and electrode holders that are intended for use by a layperson in a nonindustrial setting i
24、n accordance with the National Electrical Code, NFPA 70. Products covered by these requirements include only those welding products rated 600 volts or less, and are commonly known as hobby welders. 1.1 effective July 15, 2009 1.2 These requirements do not cover motor-generator sets or rectier- or re
25、sistance-type welding machines. These requirements do not cover industrial or professional use welders. 1.2 effective July 15, 2009 2 Components 2.1 Except as indicated in this clause, a component of a product covered by this standard shall comply with the requirements for that component. See the St
26、andards for Components appendix for a list of standards covering components generally used in the products covered by this standard. 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 t
27、he 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 components are incomplete in construction features or restricted in performance capabilit
28、ies. 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. 3 Units of Measurement 3.1 Values stated without parentheses are the requirement. Values in parentheses are explan
29、atory or approximate information. JULY 15, 2009 TRANSFORMER-TYPE ARC-WELDING MACHINES - UL 551 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 4 References 4.1 Any undated reference to a code or standard appearing in the requirements of thi
30、s standard shall be interpreted as referring to the latest edition of that code or standard. 5 Terminology 5.1 In the following text, a requirement that applies only to a particular type of product is so identied by a specic reference in that requirement to the type or types of products involved. Ab
31、sence of such specic reference or use of the term product indicates that the requirement applies to all types of products unless the context indicates otherwise. CONSTRUCTION 6 General 6.1 An enclosure, an opening, a frame, a guard, a knob, a handle, or the like shall not be sufficiently sharp to ca
32、use a risk of injury to persons during normal maintenance or use. Exception: A sharp edge that must be exposed to enable the product to perform its intended function. 6.2 A welding lead or electrode holder that is attached to a product shall be acceptable for the purpose. 7 Frame and Enclosure 7.1 A
33、 product shall be formed and assembled so that it will have the strength and rigidity necessary to resist the abuses to which it may be subjected, without increasing the risk of re, electric shock, or injury to persons due to total or partial collapse with resulting reduction of spacings, loosening
34、or displacement of parts, or other serious defects. 7.2 A product shall be provided with a case or cabinet that encloses all live parts. Exception No. 1: A exible supply cord or cable and welding leads need not be enclosed. Exception No. 2: Ungrounded secondary output terminals for the connection of
35、 welding leads, tap jacks, or similar parts connected to the secondary circuit need not be enclosed if they are: a) Limited in voltage as specied in 27.1.1; and b) Protected so as to reduce the risk of unintentional contact. 7.3 The protection referred to in Exception No. 2 to 7.2 will usually be af
36、forded if: a) Jacks are of the dead-front type, b) An uninsulated live part is recessed for a distance not less than half the minimum dimension of the opening behind which the live part is located, c) A hinged cover is provided over the terminals with smooth-edged slots or openings for the cable, or
37、 APRIL 24, 2009 TRANSFORMER-TYPE ARC-WELDING MACHINES - UL 551 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL d) In a product with a marked duty cycle more than 20 percent, an uninsulated live part, including the secondary terminals in the
38、 case of stud connections, is recessed beyond the plane of the opening. 7.4 An enclosure shall be made of cast metal, iron, steel, aluminum, copper, or brass. Exception: Other material that has been investigated and found to be acceptable for the purpose may be used. 7.5 Among the factors to conside
39、r in determining the acceptability of an enclosure are its: a) Mechanical strength, b) Resistance to impact, c) Moisture-absorptive properties, d) Combustibility, e) Resistance to corrosion, f) Resistance to distortion at temperatures to which the enclosure may be subjected under conditions of norma
40、l or abnormal use, and g) Resistance to ignition from electrical sources. For a nonmetallic enclosure, all of these factors are considered with respect to thermal aging. 7.6 The thickness of a cast-metal enclosure shall be as specied in Table 7.1. Table 7.1 Thickness of castmetal for enclosures Dime
41、nsions of location of area involved Minimum thickness, Inch (mm) Cast metal other than die-cast Die-cast metal Area of 24 square inches (154.8 cm 2 )o r less and having no dimension greater than 6 inches (152.4 mm) 1/8 (3.2) 1/16 a (1.6) Area greater than 24 square inches (154.8 cm 2 ) or having any
42、 dimension greater than 6 inches (152.4 mm) 1/8 (3.2) 3/32 (2.4) At a threaded conduit hole 1/4 (6.4) 1/4 (6.4) At an unthreaded conduit hole 1/8 (3.2) 1/8 (3.2) a The area limitation for metal 1/16 inch (1.6 mm) thick may be obtained by the provision of acceptable reinforcing ribs subdividing a lar
43、ger area. APRIL 24, 2009 TRANSFORMER-TYPE ARC-WELDING MACHINES - UL 551 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 7.7 Sheet metal to which a wiring system is to be connected in the eld shall have a thickness not less than 0.053 inch (
44、1.35 mm) if uncoated steel, not less than 0.056 inch (1.42 mm) if galvanized steel, and not less than 0.075 inch (1.91 mm) if nonferrous. 7.8 Other than as specied in 7.7, a sheet-metal enclosure shall not be thinner than specied in Table 7.2 or 7.3, as applicable. Exception: The minimum thickness o
45、f a reinforced enclosure without supporting frame may be less than specied in Tables 7.2 and 7.3 but not less than 0.020 inch (0.51 mm) for uncoated steel, 0.023 inch (0.58 mm) for coated steel, brass, aluminum, or copper if when subjected to compression and torsion forces, its strength and rigidity
46、 are shown to be not less than the corresponding properties of an enclosure of the same maximum length and width having the required thickness of metal. See Compression and Torsion Tests, Section 38. 7.9 With reference to Tables 7.2 and 7.3, a supporting frame is a structure of angle or channel or a
47、 folded rigid section of sheet metal that is rigidly attached to and has essentially the same outside dimensions as the enclosure surface. The frame also has the necessary torsional rigidity to resist the bending moments that may be applied to the surface of the enclosure when it is deected. A struc
48、ture that is as rigid as one built with a frame of angles or channels is considered to have equivalent reinforcing. 7.10 Construction considered to be without supporting frame includes: a) A single sheet with single formed anges formed edges, b) A single sheet that is corrugated or ribbed, c) An enc
49、losure surface loosely attached to a frame for example, with spring clips, or d) An enclosure surface having an unsupported edge. Table 7.2 Thickness of sheet metal for electrical enclosures, carbon steel or stainless steel Without supporting frame a With supporting frame or equivalent reinforcing b Minimum thickness Inch (mm) Maximum width, c Maximum length, d Maximum width, c Maximum length, d Inches (cm) Inches (cm) Inches (cm) Inches (cm) Uncoated Metal coated 4.0 (10.2) Not limited 6.25 (15.9)
