US Patent 11303182 Internal pressure reduction device and explosion-proof electric machine

An explosion-proof electrical machine and, more specifically, to an electrical machine comprising an internal pressure reduction device. The internal pressure reduction device comprises a base for installation in a region of the casing below the connection box, a base being configured to receive a plurality of volume filling pieces; wherein the base comprises a bottom part and a part of wall which is extended by at least a part of the periphery of the bottom part. The base may further comprise at least one engaging means for each piece of the plurality of volume filling pieces.