It always has its battery charged and waiting for a power interruption. As soon as a voltage deficit is detected, it changes the power supply from the network to the battery. This transition can last for a few hundredths of a second, which for most devices is not dangerous. This type of U.P.S. is also the cheapest but has the disadvantage of the transition. It is not suitable for sensitive or expensive devices.

These U.P.S. have the same function as offline U.P.S. with an additional advantage. They have an integrated transformer that adjusts the voltage of the current, providing your device with a constant flow. Only in the event of a power interruption, where the transition occurs, there is a disconnection from the network in order to connect the device to the U.P.S. battery. Due to this advantage, these are more expensive.

In this case, the U.P.S. works continuously adjusting the network voltage to the predetermined battery voltage. In this way, the device is continuously supplied with a constant voltage and in the event of a power interruption, there will be no need for time to transition from the network to the battery. They are the safest U.P.S. and for this reason they are also the most expensive.