Abstract: A motor operator for switchgear for use in mains power distribution systems comprising a closed cabinet (5) with an operating shaft (53) protruding there from said operating shaft being rotatable at least between two positions and has a coupling part (2). The motor operator (6,7) comprises a housing mountable on the external surface of the switchgear cabinet. A rotatable connection shaft (51) is connected to an electric motor via a drive mechanism, and has a first coupling part (52) to fit with the coupling part (2) of the switchgear in a non-rotational interlocking manner, and further has a second coupling part (54) extending from the housing to operate the contact of the switch manually and, for which purpose, the motor operator has a release mechanism releasing the connection shaft. The motor and the drive mechanism is designed as an electro-mechanical actuator with a rear mounting (23) for mounting the actuator in the housing of the motor operator and ?.