UL 5085-3
Low Voltage Transformers - Part 3: Class 2 and Class 3 Transformers

DETAILS
Edition Number:1SCC Approved:--
Edition Date:2006-04-17DOD Approved: --
Price Code:DANSI Approved: 2012-11-30
Type:ulcsa

  • SCOPE

    1 Scope

    1.1 As noted in Low Voltage Transformers – Part 1: General Requirements, UL 5085-1, or CSA C22.2 No. 66.1,  Low Voltage Transformers – Part 1: General Requirements, the requirements in Part 3 cover Class 2 transformers for use with Class 2 circuits in accordance with the National Electrical Code, ANSI/NFPA 70, or the Canadian Electrical Code, Part I, CSA C22.1. They are intended for connection to essentially sinusoidal supply sources.

    Advisory Note: For transformers intended for use in the United States, these requirements also cover Class 3 transformers for use with Class 3 circuits in accordance with the National Electrical Code, ANSI/NFPA 70, unless otherwise specified in this standard. See Annex d for Class 3 requirements.

    1.3 In addition to the items specified in Clause 1.3 of Part 1, the requirements of Part 3 do not cover:

    a)    Power supplies (a transformer provided with a rectifier is considered a power supply);

    b)    Toy transformers;

    c)    Cord and plug connected transformers other than Class 3;

    d)    Direct plug-in transformers;

    e)    Transformers intended for use in audio, radio, or television type appliances; or

    f)     Other special types of transformers covered in requirements for other electrical devices or appliances.

    Advisory Note: The requirements of Part 3 do not cover transformers intended for use in the United States having a nominal primary rating of more than 600 V and transformers having overvoltage taps rated over 660 V.

    1.7 This part is intended to be used in conjunction with Part 1. The numbering of the clauses in Part 3 corresponds to the numbered clauses in Part 1. The requirements in Part 1 apply unless modified by Part 3.

    1.8 A Class 2 transformer that includes a separate current-limiting impedance such as a resistor or a positive temperature coefficient device (PTC) is covered by these requirements.

    1.9 A Class 2 transformer that includes a resonance regulating circuit is covered by these requirements.

  • TABLE OF CONTENTS
    Expand All

    • Cover
    • Transmittal
    • UL Harmonized Standard Title Page
    • Table of Contents
      • PART 3: CLASS 2 AND CLASS 3 TRANSFORMERS
        • 1 Scope
        • 4 Construction
        • 6 Enclosure
          • 6.1 General
        • 8 Connections
          • 8.2 Wiring terminals
          • 8.5 Leads
        • 11 Spacings and Insulation
          • 11.2 Insulating material for mounting of low voltage live parts
          • 11.3 Coil insulation
          • 11.4 Insulation in lieu of spacings
          • 11.5 Spacings
          • 11.6 Separation of internal wiring circuits
        • 12 Switches, Protective Devices, and Wiring Devices
          • 12.3 Protective devices
          • 12.4 Separate current-limiting impedances
          • 12.5 Overtemperature protective devices
        • 17 Markings
          • 17.1 General
          • 17.3 Ratings
          • 17.4 Details
        • 18 Tests
        • 27 Open Circuit Secondary Voltage Test
        • 28 Output Current and Power Test
          • 28.1 Maximum current output of inherently limited transformers
          • 28.2 Maximum current of non-inherently limited transformers
          • 28.3 Maximum power of non-inherently limited transformers
        • 29 Calibration Test of Overcurrent Protective Devices
        • 30 Rated Secondary Current Test
        • 31 Rated Output Heating Test
        • 32 Dielectric Voltage-Withstand Test
          • 32.1 General
          • 32.2 Induced potential
        • 33 Overload Heating Test
          • 33.1 General
          • 33.2 Procedure
        • 34 Dielectric Voltage-Withstand After Overload Heating Test
        • 35 Overload Test of Overcurrent or Overtemperature Protective Devices
        • 36 Endurance Test of Automatically Reset Overtemperature Protective Devices
        • 37 Strain Relief Test
    • Annex A (Informative)
    • Annex C (Informative)
    • Annex D (Normative)