UPS preventive maintenance checklist
A UPS maintenance plan has three layers. At every visit: read the event log, measure every battery block, check input, output and bypass readings, and inspect fans, filters and connections. Once a year at least: a full mechanical review of the UPS and battery cabinets and an infrared scan of the electrical connections. At the manufacturer's wear-part dates: replace capacitors and fans. Critical sites visit more often, and the visit frequency is set per unit, not per building.
Key facts
- Visit frequency: at least annual (Eaton) [1]; at least twice a year for critical sites (Vertiv) [2]
- Battery readings: internal ohmic measurement each quarter, per IEEE 1188 as quoted by EnerSys[3]
- Infrared thermography: every 12 months for most equipment under NFPA 70B[4]
- Capacitors and fans: Eaton recommends replacing power-train capacitors around 7 years of operation [5], fans at the same time [6]
- Canadian framework: CSA Z463 sets maintenance requirements for electrical systems[7]
Every visit
- Download and read the event and alarm log before resetting anything
- Record input, output and bypass voltage and current on each phase, and the load per phase
- Measure every battery block: float voltage, temperature and internal resistance against its baseline [8]
- Inspect battery terminals and connectors; check torque where the manufacturer specifies it
- Check fans for noise and airflow, and clean or replace air filters
- Look for heat damage: discoloured terminals, swollen capacitors, damaged insulation
- Confirm the network card’s alerts reach the monitoring system
- Compare the load with the capacity left after removing the largest module, to confirm N+1 still holds
Once a year at least
- Full mechanical review of the UPS and battery cabinets [1]
- Transfer to static bypass and back, under a written method for the live load
- Infrared scan of UPS input, output, bypass and battery connections under load [4]
- Firmware version and settings recorded and compared with the manufacturer’s current release
- Review of the battery string’s age against its expected life, with the replacement budgeted ahead
At wear-part dates
- Eaton power-train capacitors, at about 7 years of operation [5]
- Fans, together with the capacitors [6]
- The battery string, at 80% of rated capacity or before [9]
When a test is needed
- A full-discharge capacity test when the runtime has to be proven [10]
- A load bank test after installation, major repair or a change of load
Standards cited
- IEEE 1188 (as quoted by EnerSys)
- NFPA 70B (committee report)
- CSA Z463
Common questions
How often should a UPS have preventive maintenance?
At least once a year, as Eaton recommends [1], and twice a year for critical sites, which Vertiv's service data supports [2].
What does a UPS maintenance checklist include?
The event log, electrical readings per phase, a reading of every battery block against its baseline, fans, filters and connections, a bypass transfer test, and an annual infrared scan.
How often should UPS batteries be checked?
At every visit, with an internal ohmic reading of each block every quarter per IEEE 1188 as EnerSys quotes it [3].
When should UPS capacitors be replaced?
On the manufacturer's schedule: Eaton recommends replacing power-train capacitors around 7 years of operation [5].
Sources
- Eaton, Top five preventive maintenance services for UPS health, page body
- Vertiv, The Effect of Regular, Skilled Preventive Maintenance and Remote Monitoring on Critical Power System Reliability, conclusion
- EnerSys, Safety, Storage, Operating and Maintenance Manual, VRLA Battery Systems (US-VR-OM-002), maintenance section
- National Fire Protection Association, NFPA 70B (2023 edition) second revision committee report, Table 9.2.2 Maintenance Intervals
- Eaton, Straight talk about capacitors in your UPS (WP153009EN), capacitor service life section
- Eaton, UPS fan replacement FAQs (SA161007EN), FAQ
- CSA Group, CSA Z463:24 Maintenance of electrical systems, Preface/Scope
- EnerSys, PowerSafe SBS XL Installation, Operation and Maintenance Manual, maintenance section
- CSB Energy Technology, VRLA Battery User Manual (Operation and Handling, Rev Dec 2024), failure modes table
- EnerSys, PowerSafe SBS XL Installation, Operation and Maintenance Manual, capacity testing
Updated