Choosing a UPS comes down to four separate decisions. Use this guide to prepare your requirement, then ask an APS engineer to confirm it on site.
1. Load
List every device the UPS will power and note its wattage from the nameplate or datasheet. If only amps are given: watts = volts × amps (230 V for single-phase). Add them up.
2. Capacity
Convert watts to kVA using the UPS power factor (kVA = watts ÷ (power factor × 1000)), then keep your load at about 70–80% of the UPS rating. Example: a 1,220 W load on a unity-power-factor UPS needs about 1.6 kW, so a 2 kVA unit fits.
3. Runtime
Backup time depends on the battery bank — battery Ah and the number of batteries — not on the kVA rating. Tell us how many minutes you need at your load and we will size the batteries.
4. Expansion
Plan for growth and redundancy. An N+1 design or a modular UPS such as the Liebert APM Plus lets you add power modules later without replacing the system.
Which UPS category fits the site?
| Single-phase online UPS | Three-phase online UPS | Large and modular UPS | |
|---|---|---|---|
| Capacity | 600 VA – 20 kVA | 10 – 80 kW | 50 – 1,200 kW |
| Example models | Liebert ITON CX, ITA2, GXT MT+ | Liebert ITA2 5–30 kVA, S600E / S600D, EXS | Liebert APM Plus, EXM2, EXL S1, HiPulse U |
| Typical sites | Offices, clinics, retail, network and server racks | Hospitals, labs, factories, larger server rooms | Data centres, hospital campuses, process plants |
| Form factor | Tower or rack | Tower; isolation-transformer options | Modular frames for N+1 growth |
Capacity ranges are the Vertiv models listed on apstechsystems.com. Confirm the exact model with an APS engineer.
Quarterly maintenance checklist
- Visual and cleaning — dust removal, fans and vents, signs of heat or damage
- Connections — tighten terminals; thermal check for hot spots
- Batteries — voltage, condition and a backup-time check
- Alarms and logs — review event history and active alarms
- Load and bypass — measured load against rating; bypass readiness
- Report — findings, actions taken and recommended next steps
Read more
- How to calculate UPS kVA for your load
- Modular UPS vs tower UPS: which to choose?
- What is an online UPS?
- UPS Annual Maintenance Contract (AMC)
Get your UPS sized
Share your equipment list, required backup time and site location. 📞 +91 99489 10784 / +91 99483 72888 · ✉️ info@apstechsystems.com