UL 9540-2023 Standard for Safety of Energy Storage Systems and Devices

28 June 2023, Canada-United States Joint National Standard ANSI/CAN/UL 9540 : 2023 Energy Storage System and Equipment Safety Standard Third Edition Released.

The standard update lasted more than a year, after many revisions and votes, and finally formally adopted a number of amendments. Main contents of this standard update as follows:

1. Revisions to Marking Criteria and Inclusion of AC and DC ESS Concepts.

   The concept of AC energy storage system and DC energy storage system is added to better match the different applications of energy storage system.

2. ESS capacity limits based on large-scale fire testing.
   The capacity limit of the ESS has been revised to increase the upper capacity limit based on the results of the large-scale fire test, the UL 9540A test.
3. Explosion protection for electrochemical ESS.
   Add explosion protection requirements to align with NFPA 855 and other relevant codes.
4. Addressing noise levels of ESS.
   The noise level of the ESS shall be limited to less than 85 dBA during operation.
5. Clarification of Impulse waveform in 29.2.
   Clarify the Impulse size in section 29.2.
6. Updates to Informative Appendix E.
   Update and refine Appendix E tables to be consistent with the NFPA 855.
7. Additional criteria for thermal ESS.
   Increase the structural and testing requirements for thermal energy storage systems to better evaluate the unique hazards associated with these systems.
8. Revisions to Appendix D to align with the new UL 1973 Alternative Approach for Evaluating Valve Regulated or Vented Lead Acid or Nickel Cadmium Batteries Annex.
   Appendix D has been revised to be consistent with the alternative evaluation method for valve-regulated or vented lead-acid or nickel-cadmium batteries in the new UL 1973 appendix.
9. Revisions to replace UL 508C with UL 61800-5-1.
   UL 508C revision is replaced by UL 61800-5-1.
10. Revisions to replace UL 60950-1 with UL 62368-1.
    UL 60950-1 revision is replaced by UL 62368-1.
11. Addition of UL 1778/CSA C22.2 No. 107.3 to the list of power conversion/battery charger standards referenced in 24.1.1.
    Added UL 1778/CSA C22.2 No. 107.3 to the list of power converter/battery charger standards.
12. Clarification of material and Enclosure Tests for smaller ESS.
    Clarification of housing material requirements and test requirements for small ESS
13. Use of Representative Subassemblies for Testing.
    Clarify the prerequisites for testing with representative subassemblies.
14. Revisions for flywheel ESS throughout the Standard.
    Some of the structural and test requirements for flywheel ESS have been revised to better assess the hazards of flywheel ESS technology.
15. External Warning Communication System Criteria.
    For lithium-ion battery ESS with an energy of 500kWh or more, an external warning communication system requirement is added.
16. Revisions to address hazardous fluids and liquid coolant system hazards.
    ESS containing liquids, including those with liquid cooling systems, should be equipped with leak detection to prevent potentially hazardous situations.
17. New Appendix G for Direct Injection Clean Agent Cooling Systems.
    Add Appendix G direct injection cleaner cooling system requirements, the effectiveness of the system needs to be determined by UL 9540A testing.
18. Revisions for remote software updates.

    For ESS with possible remote software updates, the requirements for related remote software updates have been revised.