Advantageously, the online, double-conversion uninterruptible power supply may be designed in a way that the override input when activated turns off the inverter. In other words, advantageously the inverter is turned off when the signal causing the bypass switch held open is received. In this way, the energy of the fault arc can be reduced even more as the inverter can be turned off very fast (e.g. in around 2 ms or even faster). For this reason, the control unit of the online, double-conversion UPS can be connected to the inverter (particularly to the gate inputs or base inputs of switching transistors of the inverter) and may force the inverter (i.e. its switching transistors) to the non-conductive state.

In yet another beneficial embodiment, the rectifier can be turned off when the signal causing the bypass switch held open is received instead of the inverter or in addition to the inverter. This is true if the rectifier is an active rectifier comprising transistors. If there is a battery being connected to the output of the rectifier and to the input of the inverter, also the battery may be disconnected from the inverter when said signal is received. This is particularly true if just the rectifier (and not the inverter) is turned off when said signal is received. Accordingly, the control unit of the online, double-conversion uninterruptible power supply can be connected to the rectifier (particularly to the gate inputs or base inputs of transistors of the rectifier) and may force the rectifier (i.e. its transistors) to the non-conductive state. The control unit of the online, double-conversion UPS can also be connected to a battery switch between the battery and the rectifier and the inverter, which battery switch may be forced to its non-conductive state.