What is the difference between 500VA online and line interactive uninterruptible power supplies?

nline 500VA UPS are also referred to as double-conversion or even triple-conversion UPS systems. This refers to the AC-DC-AC or AC-DC-DC-AC operation of the UPS as it converts the mains AC (alternating current) into DC direct current via the rectifier charger assembly and then converts the DC back to AC via the online inverter. The inverter generates a digital sinewave without a break in supply whether powered from the mains power supply or battery set. In a line interactive UPS an automatic voltage regulator (AVR) powers the load when mains power is present and an inverter ‘cuts-in’ during a power outage. The break in supply is minimal (2-4milliseconds) and most modern switch mode power supplies (SMPS) – used to power electronics, computers, servers and network devices – can work with a line interactive UPS. The principle benefit of an on-line UPS, aside from its superior waveform and no-break supply, is a built-in automatic bypass. If the UPS has an internal fault or is overloaded the connected load is automatically transferred to the mains power supply without a break in supply.