UPS Maintenance Checklist

4/28/2023

This article has been updated in 2023 to reflect current information.

Simply providing an uninterruptible power system (UPS) does not necessarily ensure an institutional or commercial facility’s equipment is protected from power-supply fluctuations and distortions. Maintenance and engineering managers must factor in regular testing and maintenance of a facility’s UPS to ensure it remains in peak operating condition, protects critical systems, and keeps them reliably operating as designed.

Regular equipment testing should be part of a facility’s UPS maintenance schedule. Such a schedule might include the following elements:

Quarterly:

• Visually inspect equipment for loose connections, burned insulation or any other signs of wear.

Semiannually:

• Visually check for liquid contamination from batteries and capacitors.

• Clean and vacuum UPS equipment enclosures.

• Check HVAC equipment and performance related to temperature and humidity.

Annually:

• Conduct thermal scans on electrical connections to ensure all are tight and not generating heat, which is the first and sometimes only indication of a problem. A non-evasive diagnostic tool helps technicians identify hot spots invisible to the human eye. Technicians should retorque if thermal scan provides evidence of a loose connection
• Provide a complete operational test of the system, including a monitored battery-rundown test to determine if any battery strings or cells are near the end of their useful lives.

Biannually:

• Test UPS transfer switches, circuit breakers and maintenance bypasses.

If a generator is part of the building’s emergency-power system and feeds the UPS, it also will need to be tested monthly or quarterly. Most facilities have a generator-maintenance schedule in place in which testing frequency is defined.

A UPS typically is sized to carry the load for a short period of time. Longer outages require backup-power generation to maintain critical services. Each facility is unique, and managers need to develop a maintenance schedule to suit each site’s specific needs.