Application of frequency conversion control technology in plate feeder
Application of frequency conversion control technology in plate feeder
Foreword:
The heavy-duty plate feeder adopts a frequency converter to control the control of two motors, with a production capacity of 4500t/h. It is introduced in detail from the principle of frequency conversion and installation and maintenance of the equipment. The energy-saving effect of the system is remarkable.
1 Inverter control principle and equipment selection
1.1 Working principle of the inverter The main circuit of the inverter consists of three parts, which is the power conversion part of the voltage regulation power supply of the asynchronous motor. The inverter mainly converts the alternating current into direct current by the rectifying unit, and the filtering unit realizes the smooth filtering of the waveform, and then The filtered DC power is reinverted into an alternating current by the inverter circuit. The control unit on the inverter completes the control of the main circuit, the drive unit, the detection unit, the micro processing unit, etc. to realize the speed control of the inverter. The inverter is to convert the 50Hz power frequency power supply into AC power of various frequencies to realize the speed regulation. The frequency conversion can smoothly change the motor speed and maintain a limited slip rate. The transmission system composed of the AC frequency converter and the motor has greatly improved in terms of controllability, rapidity, reliability and the like. Therefore, it has high efficiency, wide range and high precision speed regulation performance.
1.2 Inverter Selection This system uses two inverters to drive two motors. According to the production capacity of 4500t/h, the two-90kW motor is required to be driven by the plate feeder motor. When selecting the inverter, it should be slightly higher than the motor capacity, leaving a certain margin. Especially when one inverter drives two motors to run, usually one motor starts first and the second motor starts up. At this time, the additional running motor will generate a large starting current, and the short-time overload capacity of the inverter should be 150%, so the choice of the inverter is actually the process of optimizing the motor. The plate feeder is a constant torque load. The rated current of the inverter must be greater than the rated current of the motor. The inverter can be used in the environment of -10 °C to +45 °C without derating. The whole system of the inverter device is tested before leaving the factory. To ensure the reliability of the entire system. According to the requirements of on-site plate feeder control, under the premise of meeting production, it is preferred to select a general-purpose inverter. According to the field load characteristics, find the ABB inverter selection manual and determine the model number is ACS-800-04 -0320-3+P901. The main parameters are: rated voltage 400V, rated current Itt.max=521A, no overload application Pcont.max=250kW Light overload application IN=516A, PN=250kW, heat dissipation 7200W.
2 Inverter installation application
2.1 On-site installation
1 Installation requirements and methods. The inverter is required to be installed in a ventilated and dry room. The air temperature is not higher than +45 °C and the minimum is not lower than -10 °C. Due to the harsh environment of the installation place of the plate feeder, the dust is large, the humidity is high, and the vibration is large. The vibration will stress the components inside the inverter. Dust and moisture will affect the life and performance of the inverter components and become the cause of the failure. Therefore, the inverter is installed in the power distribution room above the motor 30m. The frequency converter adopts the form of suction at the top of the cabinet, and must be installed vertically, and the fan is at the top to reserve enough heat dissipation space, so that a large amount of heat generated by the inverter can be dissipated to achieve the purpose of cooling.
2 line connection. Since the position of the plate feeder motor is far from the position where the inverter is installed, in order to compensate for the influence of the long-line distributed capacitance, a reactor is connected at the output end of the inverter to improve the overcurrent and overvoltage of the inverter and suppress the electromagnetic of the inverter. Radiated interference and motor voltage resonance. In addition, according to the actual situation, the on-site and the central control room are required to adjust the speed of the motor. A set of potentiometers and frequency display tables are installed in the field and the central control room, and finally the inverter control terminals are connected.
2.2 Instructions for use
1 First, confirm that the main distribution transformer cabinet is powered to the inverter cabinet. When the main distribution transformer cabinet has power to the power distribution cabinet, the power-off indicator on the inverter cabinet lights up.
2 Operation to send power to the inverter, there is 380V power on and off button on the door. When the button is pressed, the 380V power on indicator lights up, and the 380V power off indicator is off, indicating that the inverter has got Electric, and the remote control box also has a 380V power-on indicator light, and the 24V control power supply indicator lights up, can operate normally.
3 When the inverter power is turned on, the inverter stop indicator lights up, indicating that the 24V low-voltage control power supply has also been powered. If it is not lit, please check if the 380V/24V switching power supply in the lower cabinet is powered or damaged.
4 If the above are normal, first confirm the operation authority, the inverter cabinet and the remote control box have a selection switch. When both are in the inverter room control, the local control indicator lights up. When the remote control is performed, the remote control is performed. The remote control lights on the box and the inverter cabinet illuminate, and which indicator lights up in order to have operating rights in the corresponding location. 5 After all the above operations are successful, the indicators on the two operation panels will be lit, and the motor can be started normally in the corresponding operation permission. There is a start and stop button on the panel, and there is a corresponding start and stop. The indicator light is on, and the corresponding speed control knob can adjust the belt speed by itself.
2.3 Test run
After the no-load test run is qualified, the load test is carried out for 8 hours. The load test requires step-by-step loading of the gears, and each gear runs for 2 hours. Load operation requirements of all gears: stable operation, stable temperature rise of full load operation ≤ 30 °C, in order to prevent sudden mine discharge from hitting the chain plate assembly, avoid starting the unit at the highest state of the accumulation, for which the height of the material is required for the machine Keep it at 1~1.5m, feed it after stable operation, and put it into normal production after passing the test run.
2.4 The effect of the inverter
The plate feeder has realized a smooth start by reducing the starting current, and greatly reduces the impact on the variable frequency motor and the mechanical equipment of the plate feeder. Since the plate feeder is always running below the rated speed, the service life of the equipment is significantly improved. The reduction in maintenance can greatly increase the start-up rate of the waste stone tape system and reduce the risk of production stoppage. When using a slip motor, when the speed of the iron plate is zero, the main motor does not stop and always maintains its rated speed.
3 Conclusion
For most enterprises, electricity tariffs are the last cost controlled by enterprises. They focus on energy-saving mechanisms and the application of advanced technologies to minimize energy consumption, that is, to protect the environment and create economic benefits for enterprises. Practice has proved that the application of the frequency converter on the plate feeder is successful. After one year, the variable frequency drive system can operate reliably and stably, effectively ensuring the rated torque of the motor at low speed, high efficiency, low failure rate, and satisfying the production. The process requirements reduce equipment maintenance costs and the economic benefits are obvious.
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