Abstract : Addressing the shortcomings of reduced-voltage starting in the traveling mechanism of hoisting machinery, this paper proposes and designs a port ship loader traveling control system using variable frequency speed regulation, providing insights for the transformation and upgrading of control systems for various operating mechanisms of large equipment. Keywords : Ship loader; Control system; Variable frequency drive Since its commissioning, the traveling system of the ship loader at Rizhao Port Coal Terminal has experienced significant problems: severe vibration during startup and shutdown, asynchronous operation of the 10 traveling motors, and high noise and severe vibration during continuous travel, introducing instability into production. 1 Causes of the Fault 1.1 Causes of Severe Vibration During Ship Loader Startup The original system design used a self-contained transformer reduced-voltage starting method. The motor's startup, shutdown, and forward/reverse control were implemented through relay logic. Therefore, when the motor starts, the entire voltage is gradually applied to the stator windings of the motor, resulting in a large starting current (4-7 times the rated current) and a large starting torque, causing severe shaking of the ship loader during startup. For motors that are frequently started, excessive starting current will cause the motor to overheat, affecting its lifespan. Simultaneously, the motor windings (especially at the ends) will deform under the driving force, potentially causing a short circuit and burning out the motor. Excessive starting current will also increase the voltage drop in the circuit, resulting in a significant decrease in grid voltage and affecting the operation of other asynchronous motors connected to the same grid, sometimes even causing them to stop or be unable to start under load. Because motor characteristics are not entirely the same, the starting torque produced by applying the same voltage to different motors is not equal, making the shaking of the ship loader more severe during startup. 1.2 Reasons for Severe Shaking When the Ship Loader Stops When the motor stops, all voltage is lost at once, without a controllable gradual voltage reduction process, making the ship loader's movement and stopping abrupt, causing severe shaking. [b][align=center]For more details, please click: Application of Frequency Converters in the Retrofitting of Ship Loader Movement Control System[/align][/b]