Abstract: The present invention relates to an arrangement in a bulb generator (G), comprising a generator housing (1, 10, 110, 210, 310, 410) arranged in a water flow for letting turbine water flow there along and towards the turbine (4), which arrangement comprises means for removing surplus heat generated during operation of the generator, which mean comprise elements which are assembled as flow channels for coolant and/or heated generator air for indirect or direct cooling of the generator air, and for the purpose of providing a cooling system which to a large degree is independent of the quality of the river water or turbine water, and which also comprises elements which are non-costly as regards manufacturing and assembly, it is according to the present invention suggested that said means (111; 411) comprise, as known per se, extruded elements, especially elements which either comprise channels or by assembly define channels (112; 412) for circulating coolant, especially circulating air, or any other appropriate c