Abstract: A modular system for the control of at least one compression system for the compression a fluid medium, said compression system comprising compressors (C1-C7) and their controllers (A1-A7) for the compression of the fluid medium, secondary treatment devices for the treatment of the medium delivered from the compressors, and piping systems (17-19, 23) for conducting the fluid medium to a place of consumption (16, 22), said control system comprising a control unit (3) containing a data processing system (34) for controlling the compression system, a user interface (35) including a display associated with it and transmission means for the transmission of control data between the control unit, the controllers and pressure sensors. The transmission means consist of data communication buses, preferably serial communication buses (30-32) and a data communication port unit (33) serving to connect the bus to the control unit (34). The controllers and pressure sensors are connected to common data communication buses.

Abstract: The invention relates to the use of variable speed control of the cooling fan on a variable speed oil-injected screw compressor. A screw compressor (11) comprises at least one stage of compression, each with a pair of rotors, variable speed compressor drive means (12), an oil reclaimer (13) from the compressed air and cooling apparatus (17) for cooling the oil extracted from the compressed air. The cooling apparatus comprises a heat exchange device and a fan (18) driven by a motor (19) which can be run at different speeds.