They can even be completely different than the input, so this system is technically classified as voltage and frequency independent (VFI). The output voltage and frequency are completely isolated from, and independent of, the input voltage and frequency. In a double conversion UPS, power flows continuously through the rectifier and then through the inverter to the ITE. The UPS must also still deliver AC to the ITE, so DC power must be converted back to AC through a device known as an inverter. For any UPS, incoming utility power is alternating current (AC), which is also what is required by most information technology equipment (ITE).īatteries, on the other hand, are direct current (DC) devices, so all battery-type UPSes must convert - or rectify - the incoming AC power to DC to charge the batteries. The most commonly used type of UPS is also the most effective, generally called a full-time or full double conversion UPS. However, kinetic energy can also be stored in heavy, rotating flywheels or energy can be stored as fuel.

For simplicity the examples and illustrations in this article will be based on that technology. Rechargeable batteries are the most common. The differences among UPS systems lies in the technology that enables them to do their jobs.Įnergy can be stored in different ways. The more energy stored, the longer power can be maintained, with practical limitations that will be discussed later.

As long as utility power is flowing, it also replenishes and maintains the energy storage. Robert McFarlane, Shen Milsom & Wilke LLCĪn uninterruptible power supply (UPS) is a device that allows a computer to keep running for at least a short time when incoming power is interrupted.

Battery notifier when ac power is lost