Frequency Screw Air Compressor

Frequency Screw Air Compressor

Precautions for frequency conversion transformation of screw air compressor

Precautions for frequency conversion transformation of screw air compressor

  • 2021-10-15

According to incomplete statistics, 60% of my country's electric energy is consumed by fans and pumps widely used in various industries, while air compressors account for about 15% of the 60%. One can imagine how big its annual consumption is. Since the air compressor is a general-purpose equipment with a complex structure, it has a long running time and is equipped with a large motor power, which reduces the power consumption of the air compressor and improves the economic operation of the air compressor, which is of certain significance to energy saving. Therefore, the frequency conversion transformation of air compressors has become an energy-saving trend for most air compressor users.

10 points for attention of screw air machine frequency conversion transformation:

1. When carrying out frequency conversion transformation, you should pay attention to keep the integrity of the original equipment main circuit and control circuit as much as possible, and the less changes to the circuit, the better; this is beneficial to the air compressor when the frequency converter fails or is overhauled. It can be easily changed back to the original control mode, which ensures that the air compressor can run in both variable frequency and industrial frequency conditions, and also makes it unnecessary to rewrite the PLC program during the transformation.

2. The start signal of the inverter is controlled by the delta connection AC contactor, which means that the inverter does not start and has no output in the star state.

3. The setting time of the time relay must be greater than or equal to the startup time of the inverter, which ensures that the inverter starts without load and frequency conversion.

4. Use the inverter's lower limit frequency to delay stop function.

5. The lower limit operating frequency of the inverter should generally be set at 35 Hz or above. If the Hz number is too low, the oil and air separator may not be able to effectively separate the oil and air and cause oil leakage from the air compressor. However, it is necessary to consider setting the lower limit frequency value according to the actual situation, because different air compressors have different mechanical matching wear and efficiency, and the lower limit frequency of non-oil leakage is not necessarily the same.

6. It is recommended to select a frequency converter with a power level one level higher than that of the air compressor to avoid frequent tripping of the air compressor during startup.

7. In order to effectively filter the high-order harmonic components in the output current of the inverter and reduce the electromagnetic interference caused by high-order harmonics, it is recommended to use an output AC reactor, which can also reduce the noise of the motor.

8. The installation position of the pressure sensor on the pipeline should be as close as possible to the air compressor, not after the filter or valve, and remember that no valve components can be installed on the pipeline between the pressure sensor and the air compressor to prevent the filter from clogging Or after the valve is closed, the air compressor will not stop and may explode. The original pressure shutdown protection switch of the air compressor should also be retained.

9. According to the requirements of the production process, after the frequency conversion transformation, the air supply pressure of the compressed air supply system is appropriately reduced, and the original high-pressure variable-flow air supply is changed to the variable-frequency constant-pressure variable-flow air supply mode.

10. The designed system should have two sets of control loops: frequency conversion and industrial frequency, to ensure that the abnormal trip protection of frequency conversion does not affect production

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