Patent ID: 7345561

Claim:
A frequency converter, for construction site devices operated with an electrical current having a higher frequency than line frequency, the frequency converter comprising: a converter device for converting the electrical current frequency; and a housing that surrounds the converter device, the housing comprising a converter receptacle that surrounds a board chamber for the converter device, a housing segment that is connected to the converter receptacle, that is isolated from the converter receptacle that acts as a cooling area, inside which there are situated cooling air ducts and a fan that is suitable for conveying cooling air through the cooling air ducts, and in the cooling area, 1) an external, first annular profile, and 2) additional annular profiles are oriented to one another in relation to the axis of the first annular profile in such a way that the annular profiles surround each other with a distance from one another, transverse to a main axial direction of the housing, so as to form at least two annular chambers that act as cooling air ducts; wherein the annular profiles are situated inside the first annular profile end with an axial spacing from the separating wall of the converter receptacle so as to form an air deflection area that acts as a cooling air duct, wherein the cooling area has a transformer chamber, adjacent to the cooling air ducts, for accomodating an isolating transformer for producing an output voltage that differs from a line voltage.