Why can't the air compressor start immediately after shutdown

The air compressor cannot be started immediately after shutdown, which may be caused by the following reasons:

1. electrical problems

1. power issues:

   • unstable or low voltage: The supply voltage of the screw air compressor is too low, and the undervoltage of the power supply will cause the motor to fail to start normally. When the motor power supply voltage fluctuates within ± 10% of the rated voltage, the motor can work normally; if it is less than 10% of the rated voltage, the motor will be difficult to start and may generate heat severely. Factors such as abnormal grid voltage, transformer overload, long power line distance or small cross-sectional area may cause low power supply voltage.
   • Circuit fault: Check whether the power supply is connected normally, whether the fuse is blown, whether the circuit is short-circuited or poor contact. If the circuit fails, it will affect the start and stop control of the air compressor.

2. Motor fault:

   • motor phase-missing operation: This is the main cause of motor winding burnout. The lack of phase may be due to the high-voltage phase loss in the transformer, the internal disconnection of the power line, the burning of the switch terminal, the poor contact of the switch contact, the poor contact of the contactor contact, the burning of the motor terminal, or the single-phase disconnection in the motor winding, etc. Caused.
   • Single-phase motor starting capacitor damaged: The starting capacitor is connected in series in the starting coil circuit. The damage of the capacitor will cause the motor to fail to start.
   • Motor winding inter-turn short circuit: This will reduce the starting torque of the motor and cause difficulty in starting the motor.

3. Control failure:

   • PLC control fault: The program may have wrong codes, garbled codes, or failure of the element circuit due to electrostatic failure.
   • Contactor or frequency converter fault: internal components contact, poor work, or electric shock melting, "arc" phenomenon, resulting in equipment can not start.
   • Sensor fault: The pressure sensor or temperature sensor may have poor contact, reverse wiring or even damage, causing the device to fail to receive the correct start signal.

2. mechanical problems

1. mechanical blockage:

   • insufficient lubricant or foreign matter stuck: If the lubricant of the air compressor is not enough, or the head is stuck with foreign matter, it will cause the motor to lock up and over-current, and the current will be too large to start.
   • Oil quality problem after long-term shutdown: After long-term shutdown, the oil may become viscous, causing the body to heat up instantly when starting, and even causing the body to malfunction. Therefore, it is recommended to replace the oil filter before starting the machine with long-term shutdown or oil filter.

2. Motor bearing jam:

   • the main reason is insufficient lubricating oil or excessive impurities entering the bearing.

3. unidirectional magnetic pull:

   • it may be due to severe bearing wear or uneven end caps on both sides, resulting in uneven air gap between the stator and rotor. In this case, the magnetic field density is lower in the region of the large gap and higher in the region of the small gap. When the motor is energized, the rotor will be "sucked" into the area with high magnetic field density and small gap, making the motor unable to start and run.

3. operational issues

1. not following the correct process to start:

   • when the air compressor is stopped for a long time and then started, do not press the start button directly, because the machine head is easy to be stuck due to lack of oil. The correct way is to start by inching, that is, press the start key to run for about 5 seconds and then press the emergency stop button at an interval of about half a minute (for permanent magnet frequency conversion, press emergency stop after the end of the pre-operation time during inching), and repeat the above steps for not less than 2 times before starting normally.

2. Improper setting:

   • improper setting or damage of pressure switch: The pressure switch is set too high or damaged, which will cause the air compressor to fail to receive the correct start signal.
   • Overload protector tripping: If the air compressor is overloaded, the overload protector may trip to prevent the air compressor from starting. At this time, it is necessary to check whether there is overload, and reset the overload protector after troubleshooting.

3. The outlet switch is not open:

   • when starting, if the outlet switch is not turned on, the air compressor cannot start normally.

4. other factors

• air line blocked: If too much moisture or dense matter accumulates in the air pipe, it will block the air circulation and affect the normal operation of the air compressor. At this time, it is necessary to clean the pipeline and install the filter.
• Failure of safety valve: When the air compressor is overloaded, the safety valve may fail, causing the machine to fail to start normally.

In summary, the air compressor can not be started immediately after the shutdown for a variety of reasons, involving electrical, mechanical, operation and other aspects. Therefore, when encountering such problems, it is necessary to investigate the possible causes one by one and take corresponding solutions. If it cannot be solved by itself, it is recommended to contact professional air compressor maintenance personnel for inspection and repair.