| 摘要 |
PURPOSE:To prevent the damage of a mill due to start as a section to be crushed is left as it is solidified by turning the mill at low speed when the mill is started, detecting the angle of rotation and currents of a motor and comparing the angle of rotation and currents detected with the relationship of the angle of rotation and currents preset. CONSTITUTION:An ultra-low speed reference SL is output to a drive 2 by an ultra-low speed command generating circuit 7 on start, and the angle of rotation thetaand current value (i) of a motor are input to a comparison arithmetic circuit 6. When a material to be crushed is solidified in a mill at that time, solidification in the mill of the material to be crushed is regarded when the current value (i) is made larger than the relationship of current-rotational angle set to the comparison arithmetic circuit 6 because currents are increased with the augmentation of the angle of rotation, and a stoppage command TRIP is output to the drive 2 from the comparison arithmetic circuit 6. When the current value (i) is made smaller than current-rotational angle preset, operation is continued, and the motor is controlled by an external speed reference SREF. The solidification of the material to be crushed in the mill at the time of start can be confirmed without monitoring the mill at a field. |
