A centrifugal separator has a rotary drum that is adapted to receive a product that can be separated into a light phase, a heavy phase, and solid sediments, a first outlet for the light phase, a closing device that opens and closes a second outlet for the heavy phase. The closing device has an electromagnetic actuator having a ferromagnetic element whereon a closing plug is mounted. The electromagnetic actuator has an electromagnetic coil that creates a magnetic field so as to attract the ferromagnetic element. A spring is connected to the closing plug so as to urge the closing plug to a closed position. The closing plug, the ferromagnetic element and the spring are connected to the rotary drum.