UL 551
Standard for Transformer-Type Arc-Welding Machines

DETAILS
Edition Number:8SCC Approved:--
Edition Date:2009-04-24DOD Approved: --
Price Code:BANSI Approved: 2018-01-08
Type:ulstd

  • SCOPE

    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 in 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 revised effective July 15, 2009

    1.2 These requirements do not cover motor-generator sets or rectifier- or resistance-type welding machines. These requirements do not cover industrial or professional use welders.


    1.2 revised effective July 15, 2009

  • TABLE OF CONTENTS
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    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 Components
          • 3 Units of Measurement
          • 4 References
          • 5 Terminology
        • CONSTRUCTION
          • 6 General
          • 7 Frame and Enclosure
          • 8 Accessibility of Live Parts
          • 9 Protection Against Corrosion
          • 10 Supply Connections
            • 10.1 General
            • 10.2 Cords and plugs
            • 10.3 Strain relief, bushings, and entrance holes
            • 10.4 Wiring terminals and leads
          • 11 Wire-Bending Space
          • 12 Grounding
          • 13 Spacings
          • 14 Mechanical Assembly
          • 15 Internal Wiring
          • 16 Current-Carrying Parts
          • 17 Electrical Insulating Materials
          • 18 Capacitors
          • 19 Fans
          • 20 Overload Protection
          • 21 Receptacles
          • 22 Switches and Control Devices
          • 23 Transformers
        • PERFORMANCE
          • 24 General
          • 25 Leakage Current Test
          • 26 Leakage Current Test Following Humidity Conditioning
          • 27 Output Test
            • 27.1 Open-circuit voltage
            • 27.2 Rated current
            • 27.3 Secondary current
          • 28 Input Test
          • 29 Short-Circuit Current Test
          • 30 Temperature Test
          • 31 Dielectric Voltage-Withstand Test
          • 32 Overload Test on Switches and Controls
          • 33 Endurance Test on Switches and Controls
          • 34 Dielectric Voltage-Withstand Test on Switches and Controls
          • 35 Short Circuit Test on Capacitors
          • 36 Abnormal Operation Test
          • 37 Stalled Fan Abnormal Operation Test
          • 38 Compression and Torsion Tests
            • 38.1 General
            • 38.2 Compression test
            • 38.3 Torsion test
          • 39 Strain Relief Test
          • 40 Permanence of Marking
            • 40.1 General
            • 40.2 Oven-aging test
            • 40.3 Immersion Test
            • 40.4 Standard-atmosphere test
            • 40.5 Unusual-condition exposure test
        • MANUFACTURING AND PRODUCTION TESTS
          • 41 Grounding Continuity
        • RATING
          • 42 Details
        • MARKING
          • 43 Details
        • INSTRUCTIONS
          • 44 Instruction Manual
    • APPENDIX A