QF - turbogenerator, S - water cooling (if it is SN, it means in water, indicating that the generator cooling method is water, hydrogen and hydrogen) , 140 - is the rated power of the generator, in units of MW, 2 - the number of magnetic poles of the generator.
In fact, generator cooling methods can be divided into air cooling, hydrogen cooling (there are two methods of external cooling and internal cooling) and water cooling (internal cooling). Different combinations can also be formed, such as: water-hydrogen-hydrogen, i.e. stator winding is water cooled, rotor winding is hydrogen cooled, stator core is cooled by hydrogen, water-water-hydrogen, i.e. the stator winding and the rotor winding are water cooled and the stator core is water cooledi to hydrogen.