Frequency converter supporting equipment supplier: The main indicators for measuring the performance of a universal frequency converter include: starting torque, control mode, torque control accuracy, speed control accuracy, speed control mode, control signal type, frequency jump function, carrier frequency, multi-stage speed setting, communication interface, etc. The correct selection of frequency converters plays a crucial role in the normal operation of the electrical control system of mechanical equipment. When selecting a frequency converter, the first step is to understand the type of mechanical equipment, load torque characteristics, starting torque, speed range, static speed accuracy, and requirements of the operating environment, and then decide which control method and protective structure of the frequency converter to use is the most suitable. The so-called suitability is a statement made on the premise of meeting the requirements of actual process production and usage scenarios in mechanical equipment, achieving the best cost-effectiveness for the application of frequency converters.
1. The appropriate frequency converter should be selected based on the characteristics of the load.
2. When selecting a frequency converter, the actual motor current value should be used as the basis for selecting the frequency converter, and the rated power of the motor can only be used as a reference. Secondly, it should be fully considered that the output of the frequency converter contains high-order harmonics, which can cause the power factor and efficiency of the motor to deteriorate.
3. If the frequency converter needs to operate with a long cable, it should be amplified by one gear or an output reactor should be installed at the output end of the frequency converter.
4. When a frequency converter is used to control several motors in parallel, it is necessary to consider that the total length of the cables from the frequency converter to the motors is within the allowable range of the frequency converter.
5. For some special application scenarios, such as high ambient temperature, high switching frequency, high altitude, etc., this may cause the frequency converter to reduce its capacity, and the frequency converter needs to be amplified by one level for selection.
6. When choosing a frequency converter for high-speed motors, it should be slightly larger than the frequency converter for ordinary motors.
7. When using a frequency converter for a variable pole motor, full attention should be paid to selecting the capacity of the frequency converter so that its maximum rated current is below the rated output current of the frequency converter.
8. When driving explosion-proof motors, the frequency converter does not have explosion-proof structures and should be placed outside of hazardous areas.
9. When using a frequency converter to drive a gear reduction motor, the range of use is limited by the lubrication method of the rotating parts of the gear. Do not exceed the maximum allowable speed.
10. When using a frequency converter to drive a wound rotor asynchronous motor, most of the existing motors are utilized. It is easy to cause overcurrent tripping due to ripple current, so a frequency converter with slightly larger capacity than usual should be selected.
11. When driving a synchronous motor with a frequency converter, the output capacity is reduced by 10% to 20% compared to a power frequency source.
12. For loads with large torque fluctuations such as compressors and vibration machines, as well as peak loads such as hydraulic pumps, it is necessary to understand the power frequency operation and choose a frequency converter with a rated output current greater than its maximum current.
13. When using a frequency converter to control a Roots blower, due to its high starting current, it is important to pay attention to whether the capacity of the frequency converter is large enough when selecting it.
14. When choosing a frequency converter, it is important to pay attention to whether its protection level matches the situation on site.
15. Single phase motors are not suitable for frequency converter drive.
If only the high reliability of the inverter body is present, but the selection and capacity matching of the inverter are not appropriate, and the resulting variable frequency speed regulation system cannot achieve high reliability or even operate, how can we ensure the normal and efficient operation of the variable frequency adjustment system?
We need to ensure that the capacity of the frequency converter matches. Firstly, select the appropriate type of frequency converter based on the nature of the load. The general principle is to match the nature of the load characteristics with the characteristics of the frequency converter.
(1) Constant torque production equipment - Within the speed range, the load torque remains basically constant. A frequency converter with constant torque performance should be selected. Its overload capacity is maintained at 150% of the rated current for 1 minute.
(2) Square torque production equipment - Within the speed range, the load torque is proportional to the square of the speed, that is, M ∝ n2. Centrifugal fans and water pumps are typical representatives of this. A frequency converter with M ∝ n2 characteristics has a smaller overload capacity, with 110% -120% rated current overloaded for 1 minute,
(3) Constant power load production equipment - within the speed range, low speed and high torque; High rotational speed and low torque. Typical equipment such as machine tools and winding mechanisms.