What is Uninterruptible power supply (UPS)
UPS is an electrical machine that provides emergency power to appliances for a short duration of time when power supply fails. It does this backup with the aid of internal batteries installed in the UPS.The primary purpose of UPS is for data protection in the effect of sudden power interruption or outright failure. For instance, it prevents computer or server from restarting or shutting down when power surges, sags or out rightly fails, which may result to loss of valuable and unretrievable data.
Some UPS also provide voltage regulation at the output such that even when the supply is unregulated, a smoothened output is delivered to the load. So in this case, UPS also serves the purpose of a voltage stabilizer.UPS also helps to give longevity to the equipment it is protecting, as it helps to cushion the damaging effects of erratic power conditions on the equipment it protects.
TYPES OF UPS
Basically, there are two broad types of UPS, Standby/offline UPS and online UPS. There are other types like line interactive, Delta conversion, Ferro-resonance and so on, but I will limit my discussion only to these two basic types common in homes and offices.
This type of UPS cannot guarantee data safety as it uses relay for switching. It runs constantly on mains (power supply) and switches to battery mode only when the voltage rises or falls below pre-determined value. Data may be lost during this short switching period. This type of UPS is available below 1KVA.
This type of UPS is used for equipment that are very sensitive to power fluctuations, such as servers, routers, switches and personal computers. For this type of UPS, no switching actually takes place since the batteries are always connected to the inverter. This type of UPS is recommended for data safety. Although the initial cost of this UPS may be higher than its offline counterpart, the maintenance cost is lower due to longer battery life.
Another advantage of this type of UPS is in its ability to provide electrical firewall between the incoming utility power and sensitive equipment. It can adapt to varying input frequency range such that the output frequency can be maintained within the acceptable window.