Computer systems and other electronic devices, due to their DC power supply design, are subject to the effects of power outages and short interruptions. They do not store sufficient energy to overcome these events and these events occur on a daily basis. Any interruption of the utility power will stop the operation of a computer system and cause loss of data, potential hardware damage and inconvenience.

What is a UPS?

A UPS is the interface between the electricity mains supply and a piece of sensitive equipment (e.g. mainframe, micro-computers, medical and electronic equipment, industrial processes, etc.). The UPS will provide a trouble-free electricity supply, or sufficient electrical autonomy to either shut systems down or switch to other alternative supplies (e.g. generators). The electricity utility companies supply alternating current at 230V, 50 Hz. The only way of storing electricity, in a battery for example, is to convert the alternating current from the mains to direct current. The UPS is a buffer battery which is placed between the mains connection and the computer. It converts the alternating current from the mains to direct current to charge the battery, then reconverts it to alternating current to supply the computer. The function of a modern UPS can now be enhanced by means of communications software linking it with various network and administrative platforms. Using SNMP protocols, which supervise all UPSs connected to networks, the UPS feeds back information: it has become intelligent.

The UPS has its own battery which provides emergency power for your system in the event of a power cut:

So you are protected against unexpected loss of data.

If the mains power remain 'off', the UPS will give you time to:

Save your files
Switch to an emergency generator
Shut the system down in an orderly manner

All UPSs filter the power supply to some extent however:

Line-interactive or on-line UPSs (discussed in a separate technical note) provide additional hardware protection from utility voltage fluctuations

A UPS can be connected to your PCs, file servers, workstations and peripherals:

So modems, external disks and other devices can all be protected, too

UPSs are also available with communications software:

To communicate with your system to be shut down in an orderly fashion.