The control device for a separator includes: a drainage pump powered by a first electric motor and an aspiration pump powered by a second electric motor. It further includes: sensor elements of known type for detecting operating parameters of the separator, such as pressure of liquid in outlet, ambient temperature, motor temperature, and for providing command signals which are proportional to the operating parameters and which command the inverters which upon receiving the command signals modify a frequency of the electrical supply current to the first electric motor and to the second electric motor.