UL 1434
Standard for Thermistor-Type Devices

DETAILS
Edition Number:1SCC Approved:--
Edition Date:1998-04-03DOD Approved: --
Price Code:BANSI Approved: --
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements apply to discrete thermistor-type devices constructed of ceramic or polymeric semiconductor material.


    1.1 revised effective April 3, 2000

    1.2 These thermistors are intended for use as:

    a)    Self-limiting devices such as heaters;

    b)    Control devices such as current limiters and inrush-current limiters; or

    c)    Sensing devices.


    1.2 revised effective April 3, 2000

    1.3 These requirements apply to positive temperature coefficient (PTC) and negative temperature coefficient (NTC) type devices.


    1.3 revised effective April 3, 2000

    1.4 Control devices, such as current limiters are not intended to replace current interrupting devices such as fuses, but are intended to provide a level of overcurrent protection complying with the end-use equipment requirements.


    1.4 revised effective April 3, 2000

    1.5 These requirements do not apply to heating cables, such as self-regulating pipe heating cable, that are constructed with thermistor-type material.


    1.5 revised effective April 3, 2000

    1.6 Deleted August 30, 2002

  • TABLE OF CONTENTS
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    • Cover
    • Transmittal
    • Table of Contents
    • UL Foreword
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 General
            • 2.1 Components
            • 2.2 Undated references
            • 2.3 Units of measurement
          • 3 Glossary
        • CONSTRUCTION
          • 4 General
          • 5 Protection Against Corrosion
          • 6 Insulating Material
          • 7 Spacings
            • 7.1 Line-voltage circuits
            • 7.2 Low-voltage and isolated-limited-energy secondary circuits
          • 8 Alternative Spacings – Clearances and Creepage Distances
          • 9 Live Parts
        • PERFORMANCE – PTC THERMISTORS
          • 10 General
          • 11 Calibration Tests
            • 11.1 General
            • 11.2 R/T measurement for PTC thermistors - all types
            • 11.3 R/T measurement for PTC heaters
            • 11.4 Hold current (I) test for PTC current limiters
            • 11.5 Time-to-trip test for PTC current limiters
            • 11.6 Surface temperature test
          • 12 Aging Test
          • 13 Heat-Cold-Humidity Cycling Test
          • 14 Overload Test
          • 15 Endurance Test
          • 16 Cold Operational Cycling Test
          • 17 Cold Thermal Cycling Test
          • 18 Limited Short-Circuit Test
            • 18.1 General
            • 18.2 Primary circuit applications
            • 18.3 Other than primary circuit applications
          • 19 Thermal Runaway Test
          • 20 Dielectric Voltage-Withstand Test (For Insulated Thermistors Only)
        • PERFORMANCE – NTC THERMISTORS
          • 21 General
          • 22 Calibration Tests
            • 22.1 General
            • 22.2 R/T measurement for NTC thermistors
            • 22.3 Surface temperature test (inrush-current limiting only)
            • 22.4 Resistance (R) and beta value (B) test for NTC thermistors
          • 23 Aging Test
          • 24 Heat-Cold-Humidity Cycling Test
          • 25 Overload Test
          • 26 Endurance Test
          • 27 Cold Operational Cycling Test
          • 28 Cold Thermal Cycling Test
          • 29 Dielectric Voltage-Withstand Test (For Insulated Thermistors Only)
        • MANUFACTURING AND PRODUCTION TESTS
          • 30 General
        • RATING
          • 31 General
        • MARKING
          • 32 General
    • APPENDIX A