In the daily use of air compressors, various problems often occur. By learning from others to repair and diagnose the reasons for air compressor failures, you can accumulate experience, and when the air compressor fails, it will be easier to determine the fault.
Below is a collection of common air compressor faults and maintenance ideas for everyone to learn together.
1. Air compressor overtemperature alarm and shutdown
The air compressor has an overtemperature alarm and shuts down. After trying to restart, it only works for a short time, and the temperature rises instantly, exceeding 100℃, and the alarm shuts down. This type of fault does not occur very frequently, 2 to 3 times a day.
No circuit break was found when measuring the thermocouple with a multimeter, and no problem was found when checking the digital temperature controller.
After replacing a digital temperature controller, the fault phenomenon remains.
The thermocouple was removed for inspection, and it was found that the nodes of the thermocouple had signs of open welding. When measuring the thermocouple with a multimeter, the nodes of the thermocouple were touched with the other hand, and the multimeter showed a momentary circuit break.
After replacing the new thermocouple, the air compressor is normal.
2. The air compressor rotates normally but there is no pressure
There are generally two reasons for this kind of fault: one is pipeline leakage, and the other is intake system failure. There are often two possible reasons for the intake system failure, namely:
The air filter is seriously dirty and blocked;
The intake valve is not open;
Referring to the working principle and electrical principle analysis of the twin-screw air compressor, only when the solenoid valve loses power or leaks internally can the intake valve be closed.
After inspection, the two reasons of pipeline leakage and filter element blockage were ruled out.
When the compressor of the twin-screw air compressor is working, listen carefully to the exhaust sound of the solenoid valve. Remove the solenoid valve for inspection and find that there is dirt inside. The valve core is not in place and the pressure is released, causing the intake valve to fail to open, the compressor has no air intake, and no pressure is generated.
Clean the solenoid valve and the air compressor will operate normally.
3. Time relay damage failure
After the air compressor pressure reaches the upper limit of 0.8MPa, the full load indicator light is on, and the pressure number displayed on the pressure gauge begins to fall, but the compressor motor still does not stop, and the exhaust solenoid valve has been activated. When the air pressure drops to the lower limit of 0.5MPa, it can produce gas again.
At that time, the voltage at the pressure switch was normal. According to the principle, it may be that the time relay does not work, the time delay normally closed point cannot be disconnected, the compressor motor contactor coil cannot be powered off, and the motor will not stop.
Remove the time relay and test it with power on, and it is found that the power supply does not enter the time relay;
Use a multimeter to measure the power supply pin of the time relay for a short circuit, and check that the solder joint on the circuit board on the inside of the pin is open;
After re-soldering the solder joint, everything is normal after the installation test;
4. The pressure reaches the upper limit instantly at startup
When the air compressor test is started, the pressure gauge shows that the pressure reaches the upper limit instantly, indicating that the compressed air produced by the compressor cannot be discharged.
A careful inspection found that the pressure-maintaining valve was stuck, which may be due to the low temperature at the time and the pressure-maintaining valve was frozen.
The pressure-maintaining valve was disassembled and checked for no abnormality. After reassembly and test run, the air compressor no longer had the phenomenon of pressure holding.
5. Exhaust temperature is too high
The fault phenomenon is that during operation, the machine trips and stops automatically, and the exhaust high temperature indicator light is on. After checking, the lubricating oil level meets the requirements and the lubricating oil quality is good.
Remove the temperature sensor resistor and measure the resistance value. There is a deviation between the resistance value and the corresponding value of the ambient temperature.
Replace the sensor resistor and restart the machine. The fault still exists.
Further inspection found that the cooling air volume of the heat exchanger of the unit's aftercooler is significantly less than the normal operating air volume.
After disassembling the aftercooler, it was found that oil and dirt accumulated in the heat sink. After cleaning, rinsing and drying, the machine returned to normal.
6. Unable to operate at full load
After the air compressor is started, the pressure is maintained at about 0.4MPa, and there is no loading or unloading action.
Stop and check the AC contactor of the loading and unloading valve control circuit in the distribution box. The action is sensitive and reliable. Further inspection of the circuit shows no abnormality.
After replacing the pressure switch and restarting the machine, the unit began to load, but the above fault occurred again after unloading.
After analysis, the loading and unloading solenoid valves failed to work, and the manufacturer's technicians required the replacement of the solenoid valves.
After disassembly, it was found that the cavity at the connection of the solenoid coil plug-in of the solenoid valve was full of oil. After cleaning and testing, the machine returned to normal.
7. Oil injection failure
During the operation of the air compressor, it was found that the lubricating oil was sprayed from the refueling port. The staff cut off the power supply in time, but the lubricating oil continued to spray in a mist for 3 minutes.
After the oil injection stopped, it was found that the seal ring of the refueling port had been severely deformed and the temperature of the screw cavity was very high.
After the unit cooled naturally, the oil drain valve was opened to drain the lubricating oil. The oil quality was checked and the maintenance record showed that the lubricating oil had been used for a total of 3060 hours, which was within the service life.
Further investigation revealed that a group of fuses in the control circuit of the cooling fan of the aftercooler were burned out. After replacing the fuse, 15L of lubricating oil was added and the machine returned to normal.