UL 991
Standard for Tests for Safety-Related Controls Employing Solid-State Devices

DETAILS
Edition Number:3SCC Approved:--
Edition Date:2004-10-22DOD Approved: --
Price Code:AANSI Approved: --
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements apply to controls that employ solid-state devices and are intended for specified safety-related protective functions.

    1.2 These requirements address the potential risks unique to the electronic nature of a control. Equipment or components employing an electronic feature shall also comply with the basic construction and performance requirements contained in the applicable end-product or component standard. These requirements are intended to supplement applicable end-product or component standards and are not intended to serve as the sole basis for investigating the risks of fire, electric shock, or injury to persons associated with a control.

    1.3 These requirements do not cover controls covered by end-product standards in which an electronic control investigation is specified.

    1.4 Sections 9 – 22 contain standardized test methods for investigating the performance of an electronic control when subjected to particular environmental stresses. The suitability of each test to a given control shall be determined by the end-product standard(s). Determination shall include an assessment of:

    a)    Whether the control will be exposed to a particular environmental stress in its application, and

    b)    Whether the response of the control to a particular environmental stress is relevant to its intended safety-related protective function in its application.

  • TABLE OF CONTENTS
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    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 Components
          • 3 Units of Measurement
          • 4 Undated References
          • 5 Glossary
        • INVESTIGATION
          • 6 General
          • 7 Failure-Mode and Effect Analysis (FMEA)
          • 8 Electrical Supervision
        • ENVIRONMENTAL STRESS TESTS
          • 9 General
          • 10 Overvoltage and Undervoltage Tests
          • 11 Power Supply Voltage Dips and Short Interruption Test
            • 11.1 General
            • 11.2 Test voltage levels
            • 11.3 Test Conditions
            • 11.4 Test procedure
          • 12 Transient Overvoltage Test
          • 13 Voltage Variation Test
            • 13.1 General
            • 13.2 Test duration and procedure
          • 14 Electromagnetic Susceptibility Tests
            • 14.1 General
            • 14.2 Electrical fast transient/burst test
            • 14.3 Electrical fast transient/burst generator
            • 14.4 Test levels
            • 14.5 Test procedure
            • 14.6 Test conditions
            • 14.7 Signal circuit fast transient test
            • 14.8 Radiated EMI test
            • 14.9 Digital equipment modulation interference test
            • 14.10 Keying interference test
          • 15 Electrostatic Discharge Test
            • 15.1 General
            • 15.2 Test methods
            • 15.3 Electrostatic discharge probe
            • 15.4 Discharge test
            • 15.5 Electric field test
            • 15.6 Magnetic field test
          • 16 Composite Operational and Thermal Cycling Test
          • 17 Test for Effects of Shipping and Storage
          • 18 Thermal Cycling Test
          • 19 Humidity Test
          • 20 Dust Test
          • 21 Vibration Test
            • 21.1 General
            • 21.2 Mounting
            • 21.3 Vibration characteristics
          • 22 Jarring Test
        • COMPUTATIONAL INVESTIGATION AND DEMONSTRATED METHOD
          • 23 General
          • 24 Computational Investigation
            • 24.1 General
            • 24.2 Preliminary procedure
            • 24.3 Parts stress method
            • 24.4 Operational test
          • 25 Demonstrated Method
            • 25.1 General
            • 25.2 Test method
        • POWER CYCLING TESTS
          • 26 General
          • 27 Overload Test
          • 28 Endurance Test
        • FOLLOW-UP PROGRAM
          • 29 General
        • RATING
          • 30 General
        • MARKING
          • 31 General
    • FOLLOW-UP PROGRAM