A UPS is a device used to protect computers and electronic equipment in the event of a significant loss or reduction of the primary power source. To achieve this, the UPS houses several batteries that take action when a loss or reduction in available power is detected. In this case, the control is transferred to the batteries and, via an inverter, the DC voltage of the batteries is converted into AC.
A UPS is not only useful in case of simple power outages: sometimes power spikes can occur that can damage our equipment: from computers, to TVs, to any device connected to the mains at that time. With an uninterruptible power supply, this danger is averted.
Standard parts of a UPS system
A UPS is basically a system that uses batteries to power a local electrical network, in the event that the power supply is compromised; therefore there are always several batteries, and a battery charger.
Since batteries use direct current and our input power is alternating current, it is necessary to convert direct current to alternating current using an inverter.
Finally, we need a way to switch from incoming AC power to battery power. For this, we use something called “transfer switch“.
A UPS provides second level surge protection, and should therefore be used in conjunction with an appropriate surge protective device (SPD), to extend the life of the UPS and connected equipment.
The different types of UPS
1. UPS in Standby (Offline)
This is the most common, the one you would normally use for a personal computer, for example.
The UPS in Standby waits for the moment to take action and, once a power failure occurs, it activates.
2. Line Interactive UPS
This type of UPS is typically found in small business infrastructures – it is very similar to a Standby UPS, but with the added ability to automatically regulate the voltage. This means that it monitors the input power, and can intervene if it detects that the voltage is a little too low, or a spike causes it to rise too high. In practice it can add or subtract energy to the grid, dynamically.
3. Online UPS (Double Conversion)
This type of UPS is very efficient, as the main power source is not the incoming power, but the battery itself. So when a power failure occurs, there is no transfer switch to close. While the input power is on, the batteries simply charge.
This UPS is also called “double conversion UPS” because it converts the input AC power to DC, then the inverter converts it back to AC for the output.
These are the most common types of UPS available. Of course, there are other types that suit a particular function, but they are for more specialized needs.
The 10 best UPS on the market
Below we have finally selected the 10 best UPS on the market according to our personal judgment, based on their objective characteristics, as well as on the reviews that have been released.