Online UPS & Battery Calculator (1Φ / 1Φ)
Headroom: ×1.25 for electronics, ×2.0–3.0 for motors/inrush.
Why Online (Double-Conversion) UPS for Offices?
Online UPS keeps the inverter running 24/7. Input AC → rectifier → DC bus → inverter → clean output AC. Transfer time is effectively 0 ms, voltage and frequency regulation are tight, and the load is isolated from sags, surges, brownouts, and generator noise. This is ideal for servers, storage, VoIP, medical/lab instruments, and sensitive IT rooms where continuity and power quality matter.
Typical Benefits
- Zero transfer time — no glitches during switchover.
- Excellent voltage/frequency regulation, low THD output.
- Superior performance on generators and “dirty” mains.
- Plays nicely with Active-PFC PSUs, AV gear, lab instruments.
Trade-offs
- Lower efficiency vs line-interactive (more heat, fan noise).
- Higher cost and larger size.
- Battery strings must be sized carefully for runtime.
Single-Phase In / Single-Phase Out
This calculator assumes 1Φ input and 1Φ output (common in offices). It sizes the UPS VA class, DC bus (series count), and battery capacity using Peukert’s law with chemistry-specific parameters.
Sizing Quick Steps
- List loads (W) and add headroom (×1.25 electronics, ×2.0–3.0 motors/inrush).
- Compute VA = P′ / PF (online PF ≈ 0.9–1.0).
- Pick the next standard VA class; map to DC bus voltage (12/24/36/48/96 V).
- Use Peukert to size Ah per string, choose battery capacity and number of parallel strings.
- Check predicted runtime and C-rate per string; adjust as needed.