In one aspect, an arrangement for cooling of an electrical machine is provided. A rotor and a stator include an air-gap arranged between the rotor and the stator. The rotor and the stator include a circulation arrangement to allow the circulation of air for cooling-purposes of the rotor and of the stator. The rotor and the stator are encapsulated by a shell which is formed to allow the flow of hot air from the rotor and the stator to a heat-exchanger. The shell is formed to allow the flow of cool air from the heat-exchanger back to the rotor and the stator for cooling-purposes. The shell includes a number of corners, while each corner is used to gather the hot air before it is guided to the heat-exchanger.