Frequency conversion screw air compressor will also be loaded and unloaded frequently? How?

Compared with the power frequency, the gas consumption of the frequency conversion compressor is adjustable, the start is smooth, and the gas supply pressure will be more stable compared with the power frequency, but sometimes the frequency conversion compressor, such as the power frequency compressor, will load and unload frequently.

According to the analysis of this phenomenon, it is found that frequent loading and unloading usually occur in the following situations:

01. The set values of air supply pressure and unloading pressure are too close

When the compressor reaches the air supply pressure, if the air consumption suddenly decreases and the frequency converter has no time to control the motor deceleration, the air production will be too large, resulting in unloading.

terms of settlement:

Set the difference between the air supply pressure and the unloading pressure larger, usually the difference is ≥ 0.05Mpa

02. When the motor operates at a constant frequency, the panel displays the fluctuation of pressure up and down

terms of settlement:

Change a pressure sensor.

03. The user’s gas consumption is unstable, which will suddenly increase and reduce a lot of gas consumption.

At this time, the air supply pressure will change. The frequency converter controls the motor to change the output air volume to maintain the stability of the air supply pressure. However, the speed change of the motor has speed. When this speed can not keep up with the gas consumption change speed at the gas consumption end, it will cause the pressure fluctuation of the machine, and then loading and unloading may occur.

terms of settlement:

(1) Users should not suddenly use multiple gas consuming devices, and can turn on the gas consuming devices one by one.

(2) Speed up the frequency conversion speed of the frequency converter to increase the change speed of the output gas volume to adapt to the change of gas consumption.

(3) Cushion with a large capacity air tank.

04. The user’s gas consumption is too small

Generally, the frequency conversion range of permanent magnet frequency conversion compressor is 30% ~ 100%, and that of asynchronous frequency conversion compressor is 50% ~ 100%. When the user’s air consumption is less than the lower limit output air volume of the compressor and the air volume reaches the set air supply pressure, the frequency converter will control the motor to reduce the frequency to the lower limit output air volume of the lower limit frequency to output the compressed gas. However, because the air consumption is too small, the air supply pressure will continue to rise until the unloading pressure and the machine is unloaded. Then the air supply pressure drops, and when the pressure drops below the loading pressure, the machine reloads.


When the machine with small gas consumption is unloaded, should the compressor enter the sleep state, or how long after unloading?

When the machine is unloaded, the gas consumption end is also using gas, but once the compressor enters the sleep state, the compressor will no longer produce gas. At this time, the air supply pressure will drop. After it drops to the loading pressure, the machine will load. There will be a situation here, that is, when the machine restarts from the sleep state, the user’s pressure is still decreasing, and the air supply pressure is likely to be lower than the loading pressure, or even far lower than the loading pressure, resulting in low air supply pressure or huge fluctuation of air supply pressure.

Therefore, it is recommended that the time to enter the sleep state after unloading should not be too short.

Post time: Dec-13-2021