In online UPS system incoming power is converted to direct current (DC) and then converted back to AC. This AC-DC/DC- AC design ensures an increased degree of isolation of the load from the irregularities on the main supply.
Line-interactive UPS systems provide both power conditioning and battery backup. This technology is particularly effective in areas where outages are rare, but power fluctuations are common. Line-interactive UPS systems support a wide range of input voltage fluctuations before switching to battery backup.
Offline/standby ups is a cost-effective choice. Better offline UPS systems switch to battery fast enough to prevent power anomalies and ride out short outages. An offline UPS protects against most spikes, but doesn’t maintain perfect power during minor sags and surges.