The invention relates to a multistage compressor unit which comprises at least two different compressor elements (1 and 2) driven by means of separate electric motors (3, 4) with an adjustable speed, whereby the outlet (8) of a compressor element (1) of one stage connected to the inlet (10) of a successive compressor element (2) of a successive stage, characterized in that the electric motors (2, 4) are identical and therefore have approximately one and the same nominal capacity, whereas between each motor (3, 4) and the compressor element (1, 2) driven thereby, a gear transmission (13, 14) is provided.
A high-pressure multi-stage centrifugal compressor is provided containing at least three compressor elements which are arranged in series as compressor stages, and at least two electric motors to drive these compressor elements. At least one compressor element forms a low-pressure stage which is driven by an electric motor. At least two compressor elements form high-pressure stages, and are arranged in series and driven by one and the same second electric motor.
