Talking about the Use of Frequency inverter
With the rapid development of power electronics technology, high-power rectifier device manufacturing process has been progressing, the frequency inverter’s controllable power is also developed to 15, and some even to 1700kW. In all walks of life frequency converter is widely used, Such as our building materials industry, the furnace grate cooler feeder ingredients system. Classifier fan water pump tower water supply equipment such as speed. Application of frequency control technology, has applied in the rotary kiln feeder stacker reclaimer and other equipment, the economic benefits are very significant.
Frequency Inverter selection Many brands and types of frequency frequency inverter is very important to choose the right, and now popular on the market and a lot of product line, in addition to a common basic functions, there are many unique auxiliary functions and parameters, first of all Understand the price and product quality, followed by in-depth understanding of the technical characteristics of the frequency inverter, in accordance with the control object requirements to select the appropriate frequency converter, from the cost point of view on the function enough on the line, rather than function as possible, from the following aspects Control frequency The frequency changer according to its control mode difference may divide into the general type and the engineering type two big categories. General Purpose Branching and Exhibition. Too low power, technology has been, and development. In a disguised form of the exhibition to use the old, selling ignorant of the use of any sister-made, change clothes, but a fan, the use of yeast large passenger off in the 61i, to meet the speed requirements of the process, frequency control The scope of speed control are in the range above, and in the ceramic cement production process, the speed range within the range can be fully meet the requirements.
But at low speed, due to air gap flux, decline, it is difficult to meet the constant power requirements, general-purpose frequency converter using a given closed-loop control, the dynamic response speed is relatively slow. Engineering-type frequency inverter in its internal automatic detection through the compensation part of the automatic limit, low-speed operation in the device can also maintain a good torque characteristics, can achieve a true sense of the closed-loop control. Engineering frequency inverter is usually a kind of control.
Installed in the form of fixed wall-mounted, power and more in the following 37kW. Book type, the power from 0.2 37 to allow a relatively small footprint, the installation can be closely packed Chassis type, power 45 200 need additional circuit and the overall chassis occupies a larger space. Cabinet type, the control power of 45 1500 in addition to the characteristics of the installed machine with the cabinet, compared with more space. Selection can be based on controlled motor power and on-site installation conditions to choose the appropriate type.
Voltage and protection class and speed range The frequency converter voltage level 10230, there are 575,660,690 grade, degree of protection class 54, should be made according to the specific circumstances of the appropriate choice, from the speed range and requirements , The frequency changer has the frequency control, the velocity modulation scope velocity modulation scope 140000000, we generally selects the FC way to be allowed to meet the production request.
Like a small power inverter is equipped with a braking resistor, the system inertia or braking time is not very short, you can not add an external resistor on the inertia of the larger and require frequent braking or braking time requirements of the external system Dynamic resistance or braking unit.
Inverter installation In the installation process, the technical support is the first ambient temperature does not exceed 4, pay attention to moisture, to ensure the installation of ventilation heat dissipation, especially the external braking resistor and brake unit, and fully consider the interference, such as limestone broken feed fan Water pump back to the brick kiln raw mill and other speed control links, inverter installation is relatively dispersed, the interference between each other does not affect the normal use, and in some production processes such as raw clinker ingredients system requires multiple inverters installed in the electricity Control room with a control panel, because the inverter itself is a strong source of interference, the work of sub-harmonic, mutual interference between the control equipment and other instruments, affecting the normal operation of the system, and control system signal transmission and more Low voltage, 5, DC side of the system work properly. In the same cabinet with the contactor solenoid valve and other coils should be connected to the surge absorber, the absorber wiring can not exceed 20, otherwise it will play the role of the antenna, interference from the power frequency network can be connected to the line reactor to be suppressed, But also to prevent the inverter on the power grid caused by harmonic pollution.
Proved by the practice, the production site conditions are better, in addition to strict requirements on the interference source shielding, the control signal transmission should be used in current 420, the production site conditions are poor, in addition to shielded cable must be used as sampling and inverter Control signal connection, and the signal line shielding network to do a separate special grounding, which can effectively suppress interference.
If the inverter is too far away from the motor, the parasitic capacitance between the motor and the inverter is too large, and the parasitic capacitance between the motor and inverter is too large. When the inverter turns on, the speed will be too high. Large peak current, the drive condition deteriorated, and even burn the switch. At the same time, the voltage drop of the long wire is also large, reducing the motor terminal voltage, resulting in an increase in stator current. To solve this problem, in terms of increasing the wire cross-sectional area, to ensure that the line voltage drop of 2 or less, and should be installed converter output reactor, used to compensate for long-distance wire generated distributed capacitance charging current. For the selection of output reactors, refer to the instruction manual provided by the manufacturer.
In the implementation of these measures is still unavoidable interference and affect the normal use of the system should consider replacing the other brands and models of the inverter.
Inverter parameter setting and debugging Do the parameter setting and debugging of the inverter, it is the fundamental guarantee measures for the normal operation of the equipment. Many questions appearing on the spot are often asked to set the parameters, but have nothing to do with the equipment itself. Reasonable and correct setting of the importance of the parameters, the parameters of the country before the electromechanical set to read the product manual.
The basic parameters of the basic parameters, including the motor nameplate rated power voltage on the speed of the cheek rate of foam and start braking and control methods. It should be noted that the input voltage to be selected according to the unit power supply situation, the most output frequency according to the production process requirements, good other parameters set the inverter as there are dozens to hundreds of parameters can be set, the actual use of large Most of the factory settings can be used only for a few special settings can meet the production requirements. If stern start is required, the start-up parameter must be set. The two parameters can be set to raise the torque, which is valid only at start-up and superimposed with the continuous lift. The sum of the points is limited to 250 or less, when the buccal rate reaches the set value, start lifting end, so you can meet the equipment start-up requirements.
After the initial operation parameters of the equipment are set, enter the initial operation phase, carefully check the line to ensure the correctness of the wiring, do not allow the equipment to be reversed to check, phase sequence. In order to ensure safety, it is recommended to use the keyboard to manually control the slow start, and view, equipment operation and output current, reasonable starting and braking torque and other parameters to adjust, and gradually accelerated to the rated speed, normal operation before into the automatic Way to complete the test run.
Conclusion These are my factory in the transformation process, the use of a large number of inverters summed up the meager experience, we rely on significant economic results to solve many other ways to start and scheduling difficult to solve the problem, there is a very practical value, with very optimistic Prospects.
