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UPS preventive maintenance is a scheduled visit that inspects, measures and cleans the UPS and its batteries, replaces what has worn, and records readings against the last visit, so failures are found while they are still small. Here is what a visit covers and how often it should happen.
A visit checks the parts that wear and the conditions that wear them: batteries, capacitors, fans and filters, power supplies, internal connections, the environment around the UPS, and the alarm and event history. Eaton names the five components that most need it (batteries, capacitors, air filters, component connections and redundant power supplies), and its aging-UPS paper names the conditions that destroy them: dirt and dust, humidity and heat. A good visit therefore measures, it does not just look: temperatures, voltages, currents, ohmic readings and the alarm log are written down and compared with the last visit.
| What happens | What is recorded |
|---|---|
| Review the alarm and event log, firmware and configuration | Alarms since the last visit and what caused them |
| Inspect the room: temperature, humidity, airflow, dust | Readings and anything that shortens component life |
| Inspect and clean filters, fans and vents | Filter condition and fan operation |
| Measure input, output and bypass electrical values | Voltages, currents and load per phase |
| Read every battery block: voltage, ohmic value, terminal temperature | Per-block readings against the baseline |
| Scan connections and cabinets for heat | Hot spots and their temperatures |
| Check and tighten terminals where the maker requires it | Connections checked and their condition |
| Check components against their service life | Dates for capacitor, fan and battery replacement |
| Confirm alarms, status and transfer readiness before leaving | Final status and the open items |
Because most UPS failures start as a slow change nobody measured. Vertiv's analysis of its field data found that UPS receiving two preventive maintenance visits a year had a mean time between failures 23 times higher than units with none, and that monitoring the battery strings more than doubled MTBF again. Eaton's aging-UPS paper adds that UPS failures account for one-fourth of unplanned data-centre outages. A visit is cheap next to the outage it prevents.
Most critical sites plan two full visits a year, with lighter checks in between, adjusted to what the maker's manual for the model requires. Eaton's guidance gives the rhythm for the parts that change fastest: air filters every month, a thermal scan for hot spots every three months, and a complete mechanical review of the UPS and battery cabinets every year. C&D's battery manual sets a similar ladder for the batteries: float voltage and current monthly, ohmic readings and terminal temperatures quarterly, individual cell voltages twice a year, and connection checks every year. Vertiv's APM2 manual requires battery and wiring terminals to be inspected and tightened at least once a year.
The schedule belongs in a maintenance contract, so it happens whether or not someone remembers; see UPS maintenance contracts.
Air filters, fans, capacitors and batteries, in roughly that order. Eaton's aging-UPS paper gives average figures: air filters about 1 year, fans a recommended replacement at 7 years, capacitors outside power modules at 7 years, and VRLA batteries at 4 years on average; electronics such as power modules and control boards at 10 years. Vertiv's EXM2 manual makes the same point in general terms: parts that wear should be inspected regularly and replaced during their estimated life. A maintenance report that tracks those dates turns a surprise failure into a planned job; see modernization and replacement planning.
We maintain three-phase UPS from the main makers, in data centres, server rooms and industrial sites, working to each maker's procedures for the model. For brand-specific service pages and the full list of services, see data-centre UPS service; for model-level references, the three-phase UPS preventive maintenance reference covers each family's published intervals.
It depends on the UPS size, the number of modules and battery strings, and whether the work needs the load on bypass. The written method states the expected duration before the visit.
Some tasks do, such as work inside power cabinets; many readings do not. The method says which steps need bypass and how the load is protected while it is.
Not by default. It is scheduled at commissioning, after repairs, or when the UPS has not been proven at load for a long time; see load bank testing.
The report says so, with the components involved and the options: replace parts, refresh the electronics, or plan a replacement UPS.
Sources, checked 2026-10-04:
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