1. Remote control system for motor groups ( 22 ) for extractor fans ( 21 ), in particular for industrial and kitchen extractor fans, characterised in that the motor group itself ( 22 ), provided dismounted from the extractor fan ( 21 ), can also be installed inside at least one protective casing ( 10 ) separate and distant from the structure of the extractor fan ( 21 ), said motor group ( 22 ) being electrically connected to the extractor fan ( 21 ), for the control of the suction speed of the group ( 22 ), by means of suitable multi-way connectors ( 17, 30 ), and said extractor fan ( 21 ) being connected to the mains through a first connector block ( 27 ), so as to connect various interchangeable motor groups ( 22 ) to the extractor fan ( 21 ).