Permanent magnet variable frequency air compressor tripping phenomenon

1. Start under pressure. Check the pressure gauge of the oil and gas barrel of the air compressor. If there is pressure, it is preliminarily judged that there is pressure in the air compressor system, which causes the air compressor to start with pressure, causing the starting current to be too high, and the air switch trips to protect the unit. The reason for this situation is usually due to the failure of the minimum pressure valve or the blockage of the pressure relief system. It may be that the pressure gauge is faulty, which misleads the maintenance personnel; the maintenance personnel can judge by checking the pressure of the oil and gas barrel; the method is very simple, open the pressure relief valve in the permanent magnet variable frequency air compressor system, when the pressure relief valve is opened, If the pressure gauge of the oil and gas barrel still shows pressure, then the pressure gauge is faulty, otherwise, it is under pressure.

2. The resistance of the air compressor head is too large. The air compressor is overloaded, which will also cause the air switch to trip. The overload of the air compressor is usually due to the excessive resistance of the head of the air compressor, which causes the starting current of the air compressor to be too large, causing the air switch to trip. Therefore, the role of lubricating oil in the screw compressor is very important. Its role is mainly manifested in four aspects: cooling, lubrication, sealing, and noise reduction. The quality of the oil and the amount of oil directly affect the quality of the air compressor. The normal operation of the air compressor and the service life of the air compressor, especially the impact on the nose part of the air compressor is obvious. There are three main situations that cause the resistance of the machine head to increase: (1) the viscosity of the lubricating oil is high; (2) the coking of the machine head; (3) Too much lubricating oil in the machine head will also lead to increased resistance. After the permanent magnet variable frequency air compressor was stopped, the oil cut-off valve was not closed in time, and a large amount of lubricating oil entered the machine head, resulting in a relatively large starting resistance when the air compressor was restarted.

The processing methods are:

• Manually crank the air compressor to check whether the head and motor can rotate freely, so as to judge whether the resistance increases. When the ambient temperature decreases, the viscosity of the oil increases, and the resistance also increases, the starting current of the motor becomes larger, and the starting time of the air compressor is prolonged. The ambient temperature at that time can be determined according to the exhaust gas temperature. Prolong the start-up time of the motor on the air switch under guaranteed use conditions, in order to meet the extension of the start-up time of the air compressor when the oil viscosity increases, to ensure the normal start-up of the air compressor, do not extend too much, too long affect other electrical equipment.

• Oil coking in the machine head is a phenomenon that often occurs in screw air compressors when the oil quality is poor or the temperature is high. Due to the coking of the machine head, the frictional resistance increases, the load of the unit increases, and the current increases. In severe cases, the screw and the rotor are bonded together by oil coke, and the unit cannot rotate freely.

• The function of the oil cut-off valve is to cut off the oil injection pipe in time when the air compressor is shut down, so as to prevent the residual pressure in the oil and gas barrel from pressing a large amount of lubricating oil into the machine head, resulting in too much lubricating oil in the machine head. The direct way to solve the problem of excessive lubricating oil in the machine head is to open the machine head, release part of the lubricating oil in the machine head, and repair or replace the oil cut-off valve at the same time.

Sollant Group-Professional Compressed Gas Solutions Provider