The breakdown of transmission shaft in the main drive system is due to too high roll torque.Overpower protection mode of motor current does not reflect the true dynamic character of roll torque.

• 轧制力矩过大是轧机主传动系统传动轴断裂的主要原因,传统的电机电流过载保护方式不能真实反映轧机主传动系统扭矩的动力学特性。