Tokyo MOU: Safety risks in emergency power supply testing

Eda Zenic -

In July 2024, the Tokyo MOU issued a safety bulletin regarding the safety risks of emergency power supply testing.

The purpose of this safety bulletin is to raise awareness about the potential risks associated with the testing of automatic emergency power sources and their connection to the emergency switchboard using simulated blackout methods. This is crucial for ensuring compliance with SOLAS (International Convention for the Safety of Life at Sea) Chapter II-1, Regulations 42 and 43.

This safety update is for:

  • Ship Operators and Shipmasters
  • Classification Societies, Maritime Administrations, their officers, investigators and technical advisors Emergency Power Supply Testing

Key Observations:

  • Simulated Blackout Testing Issues:
    • Numerous ships have been observed by Port State Control Officers (PSCOs) to successfully demonstrate emergency generator functionality using simulated blackout tests.
    • However, these tests do not always replicate real blackout conditions, leading to failures in actual emergencies.

Common Testing Practices:

  • Ships often use "Sequence Test" or "Routine Test Switch (RTS)" to simulate blackouts during routine maintenance.
  • These methods do not test the actual circuitry, relays, and printed circuit boards that would be engaged during a real blackout.

Identified Risks:

  • False Sense of Security:
    • Simulated tests can give ship engineers a false sense of preparedness, as the emergency systems might not perform as required during real emergencies.
    • This discrepancy poses significant risks to the safety of the ship, its crew, and the environment.

Regulatory Compliance:

  • SOLAS Ch. II-1 Reg. 42.3.1.2 / 43.3.1.2:
    • Emergency power sources must start automatically upon main power failure and connect to the emergency switchboard.
  • SOLAS Ch. II-1 Reg. 42.7 / 43.7:
    • Requires periodic testing of the complete emergency system, including automatic starting arrangements.

Recommendations:

ISM Management Companies:

  • Design and Wiring:
    • Ensure testing devices like the "Sequential test" selector and "Routine Test Switch" (RTS) use the actual circuit paths to meet SOLAS requirements. This ensures comprehensive testing.
  • Update Procedures:
    • Revise Company Safety Management Procedures (SMS) to include controlled blackout tests. For example, perform tests by opening the Main Control Room (MCR) bus-tie circuit breaker under normal operational conditions.
  • Awareness:
    • Understand the limitations of the "Sequential test" selector and RTS, as they may not fully meet SOLAS testing requirements.

Flag State Authorities, Classification Societies, and ISM Recognized Organizations:

  • Routine Inspections:
    • During inspections, ensure emergency generator functionality is tested using both simulated and controlled blackout methods.
    • Address discrepancies where tests are satisfactory in simulated scenarios but fail in controlled blackouts.
  • Approve Modifications:
    • Any necessary modifications to ensure proper testing should be approved by the relevant Classification Society or Recognized Organization.
  • Documentation:
    • Amendments to testing procedures should be documented within the ship’s safety management and preventive maintenance systems.