What is the final acceleration step for a DC hoist motor?

The final acceleration step for a DC hoist motor involves weakening the shunt motor. In DC shunt motors, the field winding is connected in parallel with the armature winding, which allows the motor to operate at a relatively constant speed. As load is applied and acceleration is needed, the field strength can be reduced by weakening the field current, thus facilitating a higher armature current. This adjustment helps in achieving smoother acceleration by providing the motor with the necessary torque to overcome inertia without causing an excessive drop in speed or current, thereby allowing for a controlled increase in speed during the final acceleration phase.

In contrast, the other options refer to various aspects of motor operation that do not specifically pertain to the final steps of acceleration. Increasing the motor load would typically slow down the motor and complicate acceleration, adjusting the frequency supply is primarily relevant to AC motors, and enhancing brush contact does not directly influence the specific control of acceleration in the context of a DC hoist motor.