The air compressor tripping we refer to in daily life refers to the air compressor overload, the protector is disconnected, and the air compressor stops working. After the protector trips, it takes a long time to recover, which makes the air compressor unable to be used normally, and thus delays production.
The Wolfcon R&D team has been working hard to further improve the stability of the air compressor and reduce the possibility of air compressor tripping through various R&D improvements. For example, the use of high-quality imported spare parts and the continuous optimization and improvement of the overall heat dissipation system of the air compressor make the heat dissipation effect of the air compressor better. We all know that there are many reasons that can cause air compressor tripping. The most common one is high temperature tripping, and Wolfcon permanent magnet variable frequency air compressor uses a centrifugal fan, which has better heat dissipation effect. In addition, there are some uncommon reasons for the air compressor tripping, but these uncommon factors will make it difficult for the staff to overhaul. Therefore, for maintenance personnel who are not familiar with the structure and principle of the air compressor, it will be a headache to encounter such problems. So when encountering such problems, it is recommended that engineers use the "elimination method" to eliminate the causes of the failure one by one. Let's talk about the simple "elimination method" below
1. Start with pressure
First, when the air compressor trips, check the pressure gauge of the air compressor oil and gas tank. If there is pressure, it can be preliminarily judged that there is pressure in the air compressor system, which causes the air compressor to start with pressure, resulting in excessive starting current, and the air switch trips to protect the unit. The reason for this situation is usually due to the failure of the small pressure valve or the blockage of the pressure relief system.
Of course, it is also possible that the pressure gauge is faulty and misleads the maintenance personnel; the maintenance personnel can judge by checking the pressure of the oil and gas tank; the method is very simple, open the pressure relief valve in the air compressor system, when the pressure relief valve is opened, the pressure gauge of the oil and gas tank still shows pressure, that is, the pressure gauge is faulty, otherwise, it is under pressure;
2. Excessive resistance of the air compressor head
Overloading the air compressor during use will also cause the air switch to trip. Air compressor overload is usually caused by excessive resistance of the air compressor head, resulting in excessive starting current of the air compressor, causing the air switch to trip.
Therefore, the role of lubricating oil in screw compressors is crucial. 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 normal operation and service life of the air compressor, especially the air compressor head. There are three main situations that lead to increased resistance in the air compressor head:
(1) High viscosity of lubricating oil.
(2) Coking of the air compressor head; coking of the air compressor head causes the friction resistance of the air compressor rotor to increase during operation, and the current of the air compressor increases accordingly;
(3) Excessive amount of lubricating oil in the air compressor head will also cause increased resistance. After the air compressor is shut down, the oil shut-off valve is not closed in time, and a large amount of lubricating oil enters the air compressor head, resulting in a large starting resistance when the air compressor is restarted;
The treatment methods are:
(1) Check whether the air compressor head and motor can rotate freely by manually turning the air compressor to determine whether the resistance has increased. When the ambient temperature decreases, the viscosity of the oil increases, the resistance also increases, the starting current of the motor increases, and the starting time of the air compressor is extended. The ambient temperature at that time can be determined based on the exhaust temperature.
Slightly extend the motor starting time on the air switch while ensuring safety to meet the extension of the air compressor starting time when the oil viscosity increases to ensure the normal starting of the air compressor. Do not extend it too much, as it will affect other electrical equipment.
(2) Oil coking in the head is a common phenomenon in screw air compressors when the oil quality is poor or the temperature is high. Due to coking of the head, the friction resistance increases, the load of the unit increases, and the current increases. In severe cases, the screw and the rotor are bonded together by the oil coke, and the unit cannot rotate freely.
(3) The function of the oil cut-off valve is to cut off the oil filling pipe in time when the air compressor is shut down to prevent the residual pressure in the oil and gas barrel from pressing a large amount of lubricating oil into the head, resulting in excessive lubricating oil in the head. The most direct way to solve the problem of too much lubricating oil in the machine head is to open the machine head, release some of the lubricating oil in the machine head, and repair or replace the oil cut-off valve.
3. Electrical device failure
The star-delta switch failure causes the air compressor to trip immediately after starting. During the use of the air switch, it will also be affected by the vibration of the air compressor, resulting in a shorter set start time, or even a trip at the moment of starting.
The failure of the inverter will also cause the air compressor to trip. The instability of current and voltage, high temperature of the inverter, etc. will cause the air compressor to trip.
It is more complicated to determine whether it is an electrical failure, and it has certain dangers. Therefore, I will not go into details here. Please find a professional after-sales staff to detect it.
4. Unloading valve failure
Function of air compressor unloading valve: When the gas consumption changes, the intake valve adjusts the opening degree of the valve body through the control system to match the gas consumption. It is a valve (solenoid valve) that controls the intake and non-intake of the air compressor.
The most intuitive way to judge whether the unloading valve is closed is to remove the air filter, and you can clearly see whether the air intake baffle of the unloading valve is in a closed state or an open state. If the air intake baffle is stuck due to mechanical impurities, the unit can be opened smoothly after cleaning; if the air intake baffle is stuck on the guide rod, grind the guide rod with sandpaper and apply a small amount of grease on the guide rod; if the unloading valve is seriously damaged, the unloading valve needs to be replaced.
There is another fault that is difficult to find, which is the early opening of the unloading valve. Before the air compressor is started, the unloading valve is in a closed state. When the air compressor is started, the unloading valve opens slowly. However, if the opening time is a few seconds earlier than the preset time, it will cause the starting current of the air compressor to increase and the air compressor to trip. To find this fault, maintenance personnel must master the start time of the air compressor.
5. Lubricating oil causes high temperature tripping
The temperature-controlled bypass valve controls the on-off of the valve core through a temperature-sensing probe, and determines that the opening temperature of the temperature-controlled bypass valve is within 70±10℃; after long-term use, the accuracy of the probe decreases and it cannot operate at the normal temperature point, so that the hot lubricating oil coming out of the air compressor body returns directly to the air compressor body without passing through the cooler, and the temperature of the air compressor also rises, which is difficult to control, triggering a high temperature tripping;
There is another situation, when the lubricating oil with impurities passes through the temperature-controlled bypass valve, it blocks the valve core, so that the valve core cannot be completely closed, and part of the lubricating oil returns directly to the air compressor body without passing through the cooler, resulting in poor cooling effect of the entire air compressor, triggering a high temperature tripping.
Therefore, when the lubricating oil of the air compressor fails and deteriorates, please replace the lubricating oil in time. Do not use inferior lubricating oil.