VFD for ball mill
For a long period, the chemical, cement, ceramic industries and so on normally adopt the ball mill to grind the raw materials. Usually, the decompression start-up mode is employed. The high starting current has great shocks to the equipment and power grid. Meanwhile, in working frequency, it is easily to over grid the materials. The required grinding circle is long, with low grinding efficiency and high unit product consumption. This promotes people to study and develop the ball mill system with smooth start, high grinding efficiency, high output and low consumption. This is exactly the VFD control system.
II. Working principle of the ball mill
The ball mill is mainly constituted by cylindrical barrel, end cap, bearing and transmission big gear ring and other components. The ore grinding operation is conducted in the tubular structure of the ball mill. When the grinding medium in the barrel is lifted to a certain height as the barrel revolves, the medium will fall because of gravity. The ore in the barrel will suffer from violent shocks of the medium. On the other hand, because the grinding medium revolves and rotates along the axis in the barrel, the extrusion machine and grinding force will be generated between the mediums and in the contact area between the medium and the barrel, so as to grind the ore.
III. The advantages of improved ball mill
- The VFD start is the soft start, which has avoided the start-up impulse current in the working frequency. Meanwhile, it will protect the equipment.
- It can operate as the set multi-stage PLC which is set automatically. The operation mode of multi-stage speed can reduce the input current in the status of lower than the working frequency. Under the conditions of satisfying the technological requirements of the equipment, different operating frequency and operating time are set at different time periods, thus having a good energy-save effect. The electricity saving rate can usually reach 7-18%. In addition, it has the halt memory function and elimination memory function.
- The rich protective functions of VFD, such as overflow, overvoltage, overload, phase loss, overheat and so on reduce the breakdown rate of the equipment.
- After entering into the grinding stage of the later period, the operating speed of the motor has reduced. The noise sent by the ball mill has been reduced greatly than the time period in the full-speed operation in working frequency, thus improving the working environment of the operators. It is beneficial for environmental protection and the health of the employees.
IV. Basic parameter setting of ATO VFD
|Function code||Name||Set value||Remark|
|P0.03||Operating command channel||1||Terminal operation|
|P0.09||Torque rising||3.0||Set the torque properly|
|P0.17||Acceleration time||50||Set according to the field condition|
|P3.26||Multistage frequency 1||48||Set according to technological requirement|
|P3.27||Multistage frequency 2||45|
|P3.28||Multistage frequency 3||42|
|P3.29||Multistage frequency 4||46|
|P2.05||Halt mode||1||Free halt|
||Selection of the simple PLC operating mode||1111
||The stage and frequency in storage power off|
|Continue to operate from the stage frequency in breakoff moment|
|Halt after single cycle, time unit: minute|
|P8.01||Stage 1 setting||0 0 0||set according to the technological requirement|
|P8.02||Stage 1 operating time||130|
|P8.03||Stage 2 setting||0 0 0|
|P8.04||Stage 2 operating time||280|
|P8.05||Stage 3 setting||0 0 0|
|P8.06||Stage 3 operating time||250|
|P8.07||Stage 4 setting||0 0 0|
|P8.08||Stage 4 operating time||260|
|P4.01||Function selection of the input terminal X2||17||External reset input|
|P5.09||Malfunction automatic recovery times||10||Times|
Note: The parameters in the unused multi-stage speed, simple PLC stage are all set to be zero.