To provide a means of saving an electric power consumption by carrying out a constant-velocity drive at a predetermined rotation number relating to the rotation number of a cage-type induction motor driving a rotary blade of a crusher in crushing a crushing material, and by carrying out a variable speed drive at a lower rotation number than the predetermined rotation number in case of not crushing the crushing material.
The device comprises the cage-type induction motor 1 driving the rotary blade of the crusher, a current comparator 5 comparing a load current output from a load current detector 4 detecting the load current, and a setting current previously set, and a change-over controller 6 switching a rotation speed of the cage-type induction motor 1. When the variable speed drive is carried out by an inverter controller 3, if the load current is larger than the setting current, the switch to the constant-velocity drive by a constant-velocity drive controller 2 is carried out at once, and when the constant-velocity drive is carried out by the constant-velocity drive controller 2, if the load current is smaller than the setting current, the switch to the variable speed drive by the inverter controller 3 is carried out after the predetermined time to cut waste of the electric power consumption.
KUBOTA FUTOSHI
Tomoyasu Sakaguchi
Hiroki Naito
Next Patent: RECYCLING METHOD OF WASTE CABLE