UPS fundamentals

What is a UPS?

UPS stands for Uninterruptible Power Supply

As the words suggest it is a source of mains power, either 240VAC single phase or 415VAC 3-phase which is designed not to be interrupted or stopped. A UPS sits between an incoming utility power supply and equipment to be powered.  They are designed and implemented in such a way that if the external power supply feeding the UPS were to fail, the UPS output will continue to deliver clean reliable power to the equipment until external power is restored.

Is it important?

This is vitally important in maintaining the constant operation of equipment used by organisations which provide services to customers in the public domain or to clients in life sustaining environments. This is also important if the infrastructure of a business demands that crucial and critical equipment remain powered at all times. The UPS systems can supply the power to keep this vital infrastructure running and ensure that the business operation is not compromised to the extent that productivity and profitability is affected.

How does it work?

The UPS takes in normal mains power and uses this to charge banks of batteries. These batteries in turn power an inverter which creates an output power identical to the input power but does not turn off or momentarily break if the input power is lost. The charged batteries power the inverter until the input power returns or until another source of power is fed to the UPS. The duration that the inverter runs purely on the batteries will depend on the size of the batteries and how much power is needed.

Is it reliable?

UPS systems are designed to fall back, or bypass, to the incoming power in the unlikely event that they fail. For absolute reliability, one UPS can be connected in parallel with another UPS to provide a fully redundant system.  Each UPS can have a dedicated power supply and battery supply and can be designed that in the event of one failing then the entire load can be sustained by one system alone.