The electric motor generates a torque, which is transmitted by a shaft connected to the valve stem. This rotates the ball valve. To achieve the required torque, a system of gears is connected to the electric motor shaft. The torque capacity is an important specification for selecting an actuator. It must be higher than the required torque (breakaway torque) to turn the ball valve by a certain percentage often specified by the ball valve manufacturer. The breakaway torque is the minimum torque required to turn the ball valve usually in the fully closed or fully open static positions.
