What is a UPS System?

An Uninterruptible Power Supply (UPS) is a system to automatically provide battery backup to connected loads when the mains power supplies fails or fluctuates. When mains power is present, a UPS system should provide power protection from typical mains borne pollution including: sags, surges, brownouts, spikes and electrical noise. The UPS charges its battery. When the mains power supply breaks momentarily (power outage) or for a longer duration (blackout) the battery provides power to the inverter section which converts the DC power from the battery into an AC waveform to power the load. When the mains power is restored, the battery is recharged. The load should not see any interruption in output supply from the UPS system when transferring between mains and battery power. This will depend on the type of UPS topology chosen: offline UPS (standby system), line interactive UPS or online UPS (double conversion) system.