What is a UPS
An 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. As long as utility power is flowing, it also replenishes and maintains the energy storage. The more energy stored, the longer power can be maintained, with practical limitations that will be discussed later. The differences among UPS systems lies in the technology that enables them to do their jobs.
Energy can be stored in different ways. Rechargeable batteries are the most common. For simplicity the examples and illustrations in this article will be based on that technology. However, kinetic energy can also be stored in heavy, rotating flywheels or energy can be stored as fuel.
What are the different types of UPSes?
The most commonly used type of UPS is also the most effective, generally called a full-time or full double conversion UPS. For any UPS, incoming utility power is alternating current (AC), which is also what is required by most information technology equipment (ITE).