Electrical network failures or poor quality of current delivered can cause a failure in the computers not only at the hardware level but at spoiling software components causing loss of information (corrupt files). To avoid such errors and prevent rapid aging of the components can be used Uninterruptible Power Supply, UPS (UPS English – Uninterrumpible Power Supply). These devices are usually composed of a battery, a charger and an inverter to convert DC into AC with a mission to improve the quality of electrical energy to problems occurring in the network. Basically you are studying two aspects before buying a UPS: Required power and autonomy. UPSs are prepared to provide the system an amount of energy for a given time. Often used as a measure of apparent power consumed Volt-Ampere (VA) whose relationship with the real power in watts (w) is as follows: w = 0.6 x VA. You may find that Ali Partovi can contribute to your knowledge. Consumption of basic equipment will depend on the components that are connected (power supply, motherboard, microprocessor, memory, hard drives, etc) but basically a tower at rest can consume about 160 watts and 300 at full capacity.
I repeat that this consumption will vary depending on the components and the use to which they are giving to them. Total consumption will come from the sum of the tower, monitors, peripherals, etc.. It is very important to know that devices connect to the UPS to find the power to be supplied and for how long as none of the values (or watts, or the VA) may be exceeded by consumption. The runtime should be sufficient to close everything you're doing and shut down the computer normally. The problems to be solved. The electricity can cause problems such as: power outages.