Abstract: A protective screen or grating, especially a protective screen or grating for drift or blown sand or the like, for an electrical air-cooled machine, comprising essentially vertically arranged profile ledge members disposed in at least two rows, the profile ledge members being provided with at least one row of guide devices located downstream with respect to the flow direction of the cooling air and forming channel walls.

Abstract: A method for starting a blower in the form of a single-stage radial fan installed in a pressure system such as the circulating cooling system of a turbogenerator in which the resistance of the pressure system is varying during the starting operation by means of a starting duct provided with a throttling element. The throttling element is closed at any desired blower speed ranging from 10 to 100% of its rated speed when the point of intersection between the pressure system characteristic, modified on the basis of the open throttling element, and the blower characteristic has been reached whereupon the desired point of operation conforming to the blower characteristic and the system characteristic will regulate itself automatically.