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Updated Mar 2, 2022

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HSE issue safety notice for industrial UPS systems

The Health and Safety Executive (HSE) has issued a safety notice in relation to the maintenance of industrial uninterruptible power supply (UPS) systems.

This safety notice is aimed at:

  • operators of industrial UPS systems (excluding non-maintainable UPS systems and diesel rotatory UPS systems powered by flywheel and diesel generator);
  • designers, manufacturers, importers and suppliers with responsibilities for providing information for maintenance (and all necessary revisions) of industrial UPS systems; and
  • contractors providing services that include maintenance of industrial UPS systems.

Several dangerous occurrences have now been investigated by the HSE after the failure of industrial UPS systems at onshore major hazard establishments. Failures of these industrial UPS systems usually resulted in a loss of power to industrial control systems, emergency shutdown systems and emergency mitigation systems.

In some cases, instances have led to local fires within the system, caused by failures of capacitors or batteries with smoke, excessive heat resulting in failure of the static switch and a failure to provide emergency power via a second UPS.

There have been other incidents caused by outdated firmware and component failures that have led to unplanned shutdown of a chemical processing plant, which subsequently on start-up led to an unplanned release of toxic substances into the environment, and additional demands on other safety related systems.

In all of these cases the HSE identified that information prescribed in some original equipment manufacturer's (OEM’s) standard operating and maintenance instructions relating to industrial UPS systems did not provide adequate information to allow the continued safe and reliable operation of the industrial UPS systems prior to the incident, or for their intended design life.

The HSE have set out required actions for:

  • designers, manufacturers, importers and suppliers;
  • end users and maintenance contractors; and
  • major hazard establishments,

who will potentially be affected by this issue. 

For more information, see the:


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