Line-interactive UPS (VI – Voltage Independent)

This topology operates in a similar way to an Offline UPS, but with the addition of a built in voltage stabiliser. The voltage stabiliser ensures that the output voltage from the UPS stays within a predetermined window, regardless of fluctuations in voltage from the incoming mains supply. This offers a greater level of protection fo sensitive equipment that have pre-set voltage parameters. In the event of a power failure, or variation of the mains supply

outside of the pre-set window, power is transferred to the inverter by the static switch. Changeover time for this topology is approximately 2-8ms.

Advantages

• Offers voltage stabilisation
• Lower cost than online double conversion UPS
• Quicker transfer time compared to offline UPS
• Extended runtime options
• Communication Cards available
• High Efficiency
• Protects against more power anomalies than offline UP

Disadvantages

• Still involves a changeover gap when transferring to inverter
• Only available up to 5kVA
• Protects against less power anomalies than online UP