The energy of the fault arc A can be reduced even more, if the inverter 4 is turned off when the signal causing the bypass switch held 6 open is received. The reason is that the inverter 4 can be turned off very fast (e.g. in around 2 ms or even faster). Accordingly, the control unit 7 may be connected to the inverter 4 (particularly to the gate inputs or base inputs of switching transistors of the inverter 4) and force the inverter 4 (i.e. its switching transistors) to the non-conductive state when said signal is received.

Alternatively or in addition, the rectifier 3 can be turned off when the signal causing the bypass switch 6 held open is received if the rectifier 3 is an active rectifier comprising transistors. If there is no battery 8 being connected to the output of the rectifier 3 and to the input of the inverter 4, it is sufficient to turn off the rectifier 3 (and/or the inverter 4). If there is a battery 8 being connected to the output of the rectifier 3 and to the input of the inverter 4, also the battery 8 may be disconnected from the inverter 4 when said signal is received. This is particularly true if just the rectifier 3 (and not the inverter 4) is turned off when said signal is received.