The invention relates to a power supply system (3) intended to supply power to an electrical load (C), the system comprising: two input terminals, namely a negative terminal and a positive terminal, connected to a supply mains (A) delivering an AC voltage; an input capacitor (C1) connected to one of the terminals of the system; a rectifier module (33) for generating a DC voltage on a DC bus from the AC voltage; a bus capacitor (Cb) connected between a positive line (31) and a negative line (32) of the DC bus, and upstream of the input capacitor (C1), two normally-on bidirectional semiconductor transistors (T1, T2) connected in series, fabricated in a wide-bandgap material and able to operate in current-limiting mode.