Failure analysis of the motor of oil-free air compressor
Views : 687
Author : Runningway
Update time : 2021-03-09 14:08:53
Analysis of the reasons for the damage of the air compressor motor: The damage of the water-cooled screw air compressor motor is due to various and comprehensive in-depth investigations into the air compressor and the production site. It is also related to the failure factors of the specific operation of the air compressor itself. The analysis summarizes the main points as follows: The reason for the damage of the air compressor motor is in addition to the common fault factors with other motor power equipment.
Air compressor working condition requirements: the mechanical operation of the air compressor. In the occasion of non-professional monitoring operation, the electrical control is relatively simple (especially the low-power type), generally a single unit works independently. Failure to deal with the occurrence of failures in a timely manner, relatively speaking, the repeated expansion rate of failures has increased. The start and stop of the air compressor is usually directly driven by the air pressure automatic switch (air pressure relay) to directly drive the AC contactor to automatically control the motor. Most of the pneumatic automatic switches adopt a mechanical structure, which uses springs to compress and release energy to operate the contacts. Perhaps it is due to the congenital lack of the automatic air pressure switch or the influence of different reasons such as improper adjustment and machine vibration. In the process of controlling air pressure, two abnormal actions may occur from time to time:
1. The automatic air pressure switch refuses to move when the air pressure is over. The air pressure continues to rise, making the motor unable to operate normally. Causes the motor to run overloaded and overloaded. In severe cases, failure and blockage may occur.
2. The transient bounce phenomenon of the automatic air pressure switch of the mobile air compressor (especially when the air pressure is close to the upper limit or the lower limit critical state) simultaneously causes the AC contactor to generate synchronous bounce. As a result, the main contacts of the AC contactor are burnt out or sticked under frequent starting current impacts, causing shutdown or phase failure operation.
Automatic exhaust valve failure: Air compressors generally do not have automatic exhaust devices. Automatic exhaust and pressure reduction after shutdown, when the air pressure reaches the set pressure. Preset the next no-load start, and after the exhaust valve fails, the air pressure in the cylinder of the air compressor cannot be released, which is equal to the start of the motor with load, which may cause difficulty in starting or stall failure. Sudden power outage during operation: The air compressor with automatic gear control encounters a sudden power outage (such as mains power, self-provided power conversion) because the air pressure in the cylinder of the air compressor is too late to release and restart. When the motor is under heavy load starting, it is likely to form a locked-rotor fault. Too frequent starting: due to irregular peripheral air consumption, when the air consumption is large, the motor is forced to start frequently. The accumulation of heat surplus generated by the large current during starting is not easy to dissipate, which will cause the motor to overheat, which may cause the motor to burn out. Heavy load shutdown: Unlike other equipment, the shutdown of the air compressor is when it reaches the set upper limit and maximum pressure. The AC contactor acts in sections under heavy load and high current. At this time, the arcing spark is the most serious, which poses a great threat to the damage of the AC contactor. Due to the damage of the AC contactor, it will cause the nature of the power failure. Such as unbalance (phase loss) and other operating conditions. Mechanical failures of screw air compressors: air compressors are of uneven load nature, with high vibration and noise, mechanical failures such as obstruction of transmission components and wear and damage, which can easily cause motor overload (locked rotor, blockage, etc.)
Current Status of Air Compressor Motor Protection
The above-mentioned typical failure factors indicate. The maintenance device of the air compressor motor is still based on the thermal relay. Of course, the correct and reasonable maintenance of the air compressor motor is very urgent and necessary. But so far. As a traditional maintenance product, thermal relay has the advantages of simple structure, convenient use, low price, and certain inverse time characteristics. However, its working principle and performance characteristics determine its small function, large power consumption, low precision, rough setting, and easy Affected by the environment, poor repeatability, large errors and other deficiencies and defects. Reliable protection cannot be achieved for the malfunctions such as locked rotor and temporary overload during the motor starting process, so the actual protection requirements of the air compressor cannot be met. Therefore, maintenance failure is also an undeniable fact. The society is developing, science and technology are advancing, and backward products are being eliminated. Thermal relays have completed their historical missions.
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