Assembly containing a damping device and an electrical protection device, said device making it possible to damp the movement of the rotary control shaft of at least one mobile contact (4, 5, 6) in said electrical protection device, said device comprising, per phase, a mobile contact (4, 5, 6) which can adopt at least two positions, respectively a closed position in which said mobile contact is in contact with the corresponding fixed contact (1, 2, 3, 8, 9, 10), and an open position in which the two, respectively fixed and mobile contacts are separated, the mobile contact(s) being driven by the aforementioned rotary shaft which is controlled by the mechanism of the device, said device comprising: - an arm assembly which is mobile in translation relative to the frame, and comprising two shafts (29, 30) which confine a damper fitted between the two shafts (29, 30), and being able to receive by means of these two shafts impacts in two opposite directions during the translation of the mobile assembly; and - means for connecting mechanically the arm assembly and the aforementioned shaft, such as to damp by translation of the arm assembly all the movements of the shaft which are controlled by the mechanism, during each change of position of the device, characterised in that said device comprises a disc which is integral in rotation with the aforementioned shaft, and comprises at least one groove portion (11a, 11b, 11c), each groove portion (11a, 11b, 11c) having a length corresponding to the course in rotation of the shaft, between a position of opening and a position of closure of two respectively, fixed (1, 2, 3, 8, 9, 10) and mobile (4, 5, 6) contacts, each groove portion (11a, 11b, 11c) comprising at its two opposite ends a surface which forms a stop element, these stop elements coming into contact with a stop shaft which is integral with the aforementioned mobile assembly during the displacement of the shaft from an opening position to a closure position and conversely, the impact which is transmitted during the contact driving the mobile assembly in translation, such as to damp the movement of the shaft by compression of the damper between one or the other of the so-called second and third shafts and a fixed shaft which is integral with the frame. - an arm assembly which is mobile in translation relative to the frame, and comprising two shafts (29, 30) which confine a damper fitted between the two shafts (29, 30), and being able to receive by means of these two shafts impacts in two opposite directions during the translation of the mobile assembly; and - means for connecting mechanically the arm assembly and the aforementioned shaft, such as to damp by translation of the arm assembly all the movements of the shaft which are controlled by the mechanism, during each change of position of the device, characterised in that said device comprises a disc which is integral in rotation with the aforementioned shaft, and comprises at least one groove portion (11a, 11b, 11c), each groove portion (11a, 11b, 11c) having a length corresponding to the course in rotation of the shaft, between a position of opening and a position of closure of two respectively, fixed (1, 2, 3, 8, 9, 10) and mobile (4, 5, 6) contacts, each groove portion (11a, 11b, 11c) comprising at its two opposite ends a surface which forms a stop element, these stop elements coming into contact with a stop shaft which is integral with the aforementioned mobile assembly during the displacement of the shaft from an opening position to a closure position and conversely, the impact which is transmitted during the contact driving the mobile assembly in translation, such as to damp the movement of the shaft by compression of the damper between one or the other of the so-called second and third shafts and a fixed shaft which is integral with the frame.