A prosthetic system having a microprocessor-controlled socket evacuation device, and a method of retaining a prosthesis on the residual limb of an amputee using such an evacuation device are described herein. The evacuation device can include an electrically powered vacuum pump. The evacuation device can be operated in a manner that automatically adjusts the socket vacuum level to correspond to a determined activity level of a user. The microprocessor control can also limit operation of the evacuation device to certain determined portions of a user's gait cycle.
