Spark protected alternator

Abstract

An explosion-proof type rotating electrical machine having excellent cooling and brush powder discharge capabilities. A drive shaft of a rotor is provided with slip rings for supplying current to a field coil, which is energized through brushes capable of activating the field coil by contacting with the slip rings. The brush compartment incorporated with the brushes and slip rings and the outside of the rotating electrical machine are connected with each other through an air suction path, the brush compartment and an inside space of the rotating electrical machine are connected with each other through an air blowing path, in which a flame stifling wire net is provided. When operating the rotating electrical machine in a flammable gas atmosphere, sparks generated due to a contact failure between the brushes and the slip rings ignite the flammable gas filled in the brush compartment to produce flames, the flames then reach the flame stifling wire net by a blowing cool air sucked from the air suction port, where the flames are cooled and extinguished by the flame stifling wire net. Brush powders are discharged to the outside of the brush compartment from the air blowing path by the cooling air.