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What happened?

The Health and Safety Executive (HSE) has recently carried out several investigations into dangerous occurrences that resulted from a failure of industrial uninterruptible power supply (UPS) systems.

These industrial UPS systems were supplied by various manufacturers. 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.

What was the issue?

The HSE investigations identified in all cases that the information for maintenance included in the original equipment manufacturer's (OEM’s) operating and maintenance instructions did not provide adequate information to allow the continued safe and reliable operation of the industrial UPS systems prior to the incident.

For example, some components had much shorter life expectancies than initially predicted (e.g. batteries, filter capacitors, cooling fans) and did not last the expected life cycle of the UPS system, but were not detailed to be replaced at suitable intervals within the operation and maintenance (O&M) manuals of the equipment. In addition, end users are not made aware of any design changes or limitations on use that have a safety implication. For example, firmware upgrades might become essential to ensure continued reliability.

What needs to be done?

• University College London (UCL) has a number of UPS systems at various locations across the campus. The condition of these installations should be assessed to ensure they are fit for purpose and present no danger.
• The latest revision of information for maintenance from the original equipment manufacturer (OEM) should be acquired for all UPS systems at UCL
• A review of the relevant operation and maintenance (O&M) manuals shall be carried out to ensure they are still current/relevant for the UPS system they represent
• A detailed and up to date schedule of all industrial UPS systems and other emergency back-up systems located in UCL premises should be produced.
• A review of the current maintenance procedures and frequency of maintenance for these systems should be conducted. The review should also examine how issues are raised, rectified and recorded.

Full information on this safety alert can be found on the .