A line interactive UPS is a Voltage Independent (VI) uninterruptible power supply as defined by BS EN 62040. The UPS has a built-in automatic voltage regulator (AVR) or automatic voltage stabiliser (AVS) to respond to sags, surges and brownouts, an EMC/Transient filter for spikes and electrical noise and an inverter which will generate a sinewave or pseudo sinewave output when the mains power supply fails.