A centrifugal separator for cleaning gas containing contaminants includes a stationary casing enclosing a separation space through which a gas flow is permitted, a gas inlet extending through the stationary casing and permitting supply of the gas to be cleaned, a rotating member including a plurality of separation members arranged in said separation space and being arranged to rotate around an axis of rotation, a gas outlet configured to permit discharge of cleaned gas and including an outlet opening through a wall of the stationary casing, a drainage outlet configured to permit discharge of liquid impurities separated from the gas to be cleaned and an electrical motor for rotating the rotating member. The centrifugal separator further includes a control unit configured to control the operation of the electrical motor and to drive the electrical motor in at least two different operational modes and to further switch between operational modes depending at least on information of at least one measured internal parameter of the electrical motor.