Offline Topology
In an offline (also called standby) UPS, the connected load is fed directly from utility under normal mains conditions and the inverter sits idle, drawing minimal power. When the UPS detects a power event — outage, deep sag, or out-of-spec frequency — it transfers the load to inverter feed in a small but non-zero window (typically 4–10 ms). Because the load is on raw mains most of the time, the unit does not condition the waveform and offers no protection from sub-trip-threshold sags or surges.
The trade-off versus line-interactive and online double-conversion is simple: lowest cost, highest steady-state efficiency, and no continuous waveform protection. Suitable for short hold-up of non-critical PC-class loads where the goal is “save the document and shut down cleanly,” not “run through extended outages.”
Implemented by
- iPlug — Riello’s entry-level offline UPS at 600 / 800 VA
Connections
- iPlug — implements_feature, source: https://standbysystems.co.za/ups_products/iplug-600-800va/
- Line-Interactive — relates (next-tier-up alternative), source_status: inferred
- Online Double-Conversion — relates (highest-protection alternative), source_status: inferred