Frequency control of plate feeders
1 Problem Limestone crusher was selected to use a 2PF-1212 impact crusher for primary crushing. The feeding system uses a WBZ1500×12000 plate feeder and the motor is model Y225M-4. Because the feeder cannot adjust the line speed of the system, when the feeding is excessive, the feeding can only be stopped by stopping the motor, which brings certain difficulties to the control of the feeding amount, especially in rainy weather, and the material has a large viscosity. Motors often start and stop with heavy loads, which have a large impact on the motor and transmission system. In addition, the interval feeding is not easy to control the uniformity of the feeding, and has a great influence on the size of the broken-out material, and it is difficult to meet the production requirements.
2 system transformation and debugging Consider the crushing system requirements, the inverter can not only control the motor speed operation, but also can provide enough torque output. For this reason, among the many inverter brands, we have chosen ACS600 series inverters manufactured by ABB, whose main features are as follows:
1) The direct torque (DTC) control technology has changed the control mode of traditional vector-type inverters. Without speed feedback at zero speed, the full-torque torque output characteristics can be achieved, and the dynamic response is fast and stable. Control, starting torque up to 200% of rated torque, can withstand 150% of the overload l minutes.
2) Provide all-round protection for the motor, including overvoltage, overcurrent, phase loss, and motor stall and temperature rise protection. At the same time, the motor can be soft-started to make the equipment run smoothly, thereby prolonging the service life of the equipment and reducing vibration. Impact and noise, providing a good working environment.
Through tests, it was found that when the plate feeder is running normally, the three-phase average current is only 30A (rated current 84.6A), and the motor selection is obviously larger. After project demonstration, the use of frequency converter is fully able to achieve better results.
Inverter installation and wiring are relatively simple. Under normal circumstances, simply connect the inverter in series with the motor main circuit cable. For the convenience of operation, a 10kΩ speed adjustment potentiometer and a digital display tachometer can be added to the console, while the original start and stop control loop does not need to be changed.
Combined with the current state of the crushing system, in order to prevent subsequent crushing of no-load operation and low-frequency operation, higher harmonics cause the motor winding heating and other unfavorable factors to occur, the frequency lower limit is set to 10Hz (speed 300r/min), the upper limit is 50Hz (rotation speed 1470r/min), through the pointer potentiometer, according to the actual needs of production, any adjustment.
3 Effect of transformation 1) Wide range of speed control The feed control realizes stepless speed regulation, and the amount of feeding can be adjusted in time according to the actual incoming material and subsequent crushing conditions, and the expected effect of continuous and uniform feeding is achieved.
2) The motor starts without impact damage When the three-phase AC asynchronous motor adopts the direct starting mode, the starting current is about 5 to 7 times of the rated current. After the technical reform, the starting current is less than 1.7 times of the rated current, and the intermittent feeding mode of frequently starting and stopping the motor is eliminated, the operation status of the equipment is greatly improved, and the equipment maintenance workload of the on-site workers is reduced.
3) The power-saving effect is significant through more than two months of operation. In normal operation, the motor operating frequency is 20-40 Hz, the average power network current is 8-15 A, and the energy-saving rate is over 40%.
Jiangsu Tianpeng Company Telephone
1 Problem Limestone crusher was selected to use a 2PF-1212 impact crusher for primary crushing. The feeding system uses a WBZ1500×12000 plate feeder and the motor is model Y225M-4. Because the feeder cannot adjust the line speed of the system, when the feeding is excessive, the feeding can only be stopped by stopping the motor, which brings certain difficulties to the control of the feeding amount, especially in rainy weather, and the material has a large viscosity. Motors often start and stop with heavy loads, which have a large impact on the motor and transmission system. In addition, the interval feeding is not easy to control the uniformity of the feeding, and has a great influence on the size of the broken-out material, and it is difficult to meet the production requirements.
2 system transformation and debugging Consider the crushing system requirements, the inverter can not only control the motor speed operation, but also can provide enough torque output. For this reason, among the many inverter brands, we have chosen ACS600 series inverters manufactured by ABB, whose main features are as follows:
1) The direct torque (DTC) control technology has changed the control mode of traditional vector-type inverters. Without speed feedback at zero speed, the full-torque torque output characteristics can be achieved, and the dynamic response is fast and stable. Control, starting torque up to 200% of rated torque, can withstand 150% of the overload l minutes.
2) Provide all-round protection for the motor, including overvoltage, overcurrent, phase loss, and motor stall and temperature rise protection. At the same time, the motor can be soft-started to make the equipment run smoothly, thereby prolonging the service life of the equipment and reducing vibration. Impact and noise, providing a good working environment.
Through tests, it was found that when the plate feeder is running normally, the three-phase average current is only 30A (rated current 84.6A), and the motor selection is obviously larger. After project demonstration, the use of frequency converter is fully able to achieve better results.
Inverter installation and wiring are relatively simple. Under normal circumstances, simply connect the inverter in series with the motor main circuit cable. For the convenience of operation, a 10kΩ speed adjustment potentiometer and a digital display tachometer can be added to the console, while the original start and stop control loop does not need to be changed.
Combined with the current state of the crushing system, in order to prevent subsequent crushing of no-load operation and low-frequency operation, higher harmonics cause the motor winding heating and other unfavorable factors to occur, the frequency lower limit is set to 10Hz (speed 300r/min), the upper limit is 50Hz (rotation speed 1470r/min), through the pointer potentiometer, according to the actual needs of production, any adjustment.
3 Effect of transformation 1) Wide range of speed control The feed control realizes stepless speed regulation, and the amount of feeding can be adjusted in time according to the actual incoming material and subsequent crushing conditions, and the expected effect of continuous and uniform feeding is achieved.
2) The motor starts without impact damage When the three-phase AC asynchronous motor adopts the direct starting mode, the starting current is about 5 to 7 times of the rated current. After the technical reform, the starting current is less than 1.7 times of the rated current, and the intermittent feeding mode of frequently starting and stopping the motor is eliminated, the operation status of the equipment is greatly improved, and the equipment maintenance workload of the on-site workers is reduced.
3) The power-saving effect is significant through more than two months of operation. In normal operation, the motor operating frequency is 20-40 Hz, the average power network current is 8-15 A, and the energy-saving rate is over 40%.
Jiangsu Tianpeng Company Telephone
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