Last reviewed 22 March 2022

Information prescribed in some original equipment manufacturer's (OEM’s) standard operating and maintenance instructions relating to industrial uninterruptible power supply (UPS) systems may not be adequate to ensure the continued safe and reliable operation for the intended design life.

The Health and Safety Executive (HSE) has carried out several investigations into dangerous occurrences that resulted from a failure of industrial UPS systems at onshore major hazard establishments.

It has now issued a safety notice. This requires designers, manufacturers, importers and suppliers to review the information for maintenance (including inspection) which they provide with their current range of industrial UPS systems to ensure that it satisfies legal requirements.

They should review information for maintenance provided historically to all end users of their industrial UPS systems and determine if they need to provide more up to date information, resulting from experience in use, design modifications, limitations on use or anything else that gives risk to a serious risk to health and safety.

The failure of these industrial UPS systems typically resulted in a loss of power to industrial control systems, emergency shutdown systems and emergency mitigation systems. Some of these incidents have led to localised fires within industrial UPS systems due to failures of either 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.

Other incidents due to component failures and outdated firmware have led to unplanned shutdown of a chemical processing plant which subsequently on start-up led to an unplanned release of toxic substances into the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 demand placed upon other safety-related systems.