What are the factors that cause motor damage？

What are the factors that cause motor damage？ What are the factors that cause damage to the compressor motor: 　　 1. Abnormal load and stall 　　 Motor load includes the load required to compress the gas and the load required to overcome mechanical friction. If the pressure ratio is too large or the pressure difference is too large, the compression process will be more difficult. The increased frictional resistance caused by the failure of lubrication and the motor stall in extreme cases will greatly increase the motor load. Lubrication failure and increased frictional resistance are the primary causes of abnormal loads. 　　Dilution of the lubricating oil, excessive heating of the lubricating oil, coking and deterioration of the lubricating oil, and lack of oil will destroy the normal lubrication and cause lubrication failure. Dilute the lubricating oil back to the liquid, which affects the formation of the normal oil film on the friction surface, and even wash away the original oil film, increasing friction and wear. 　　Overheating of the compressor will cause the lubricating oil to become thinner or even scorch at high temperature, affecting the formation of normal oil film. The oil return of the system is not good, the compressor lacks oil, and naturally cannot maintain normal lubrication. The crankshaft rotates at high speed and the connecting rod and piston move at high speed. The friction surface without oil film protection will quickly heat up. The local high temperature makes the lubricating oil evaporate or scorch quickly, making the lubrication of this part more difficult. It can cause serious local wear within a few seconds. 　　 2. Short circuit of winding caused by metal shavings 　　 The sources of metal shavings include copper pipe shavings left during construction, welding slag, metal shavings that fall off during compressor internal wear and parts damage (such as broken valve pieces). 　　 For hermetic compressors (including hermetic scroll compressors), these metal chips or debris will fall on the windings. For semi-hermetic compressors, some particles will flow in the system with gas and lubricating oil, and finally gather in the windings due to magnetism; and some metal chips (such as those caused by bearing wear and motor rotor and stator wear (bore sweeping)) It falls directly on the winding. It is only a matter of time before a short circuit occurs after metal chips have accumulated in the winding. 　　 3. Power supply phase loss and abnormal voltage 　　 Abnormal voltage and phase loss can easily destroy any motor. 　　 The power supply voltage variation range cannot exceed ±10% of the rated voltage. The voltage imbalance between the three phases cannot exceed 5%. High-power motors must be powered independently to prevent low voltages when other high-power equipment on the same line starts and runs. 　　 The motor power cord must be able to carry the rated current of the motor. If the compressor is running when a phase loss occurs, it will continue to run but will have a large load current. The motor winding will quickly overheat, and the compressor will be thermally protected under normal conditions. 　　 Fourth, insufficient cooling 　　 Compressors with higher power are generally return air cooled. The lower the evaporation temperature, the smaller the system mass flow. 　　When the evaporation temperature is very low (exceeds the manufacturer's regulations), the flow is not enough to cool the motor, and the motor will run at a higher temperature. Air-cooled compressors (generally no more than 10HP) have little dependence on the return air, but they have clear requirements on the compressor's ambient temperature and cooling air volume. 　　 A large amount of refrigerant leakage will also reduce the system mass flow, and the cooling of the motor will also be affected. Some unattended refrigeration equipment often finds that a large amount of refrigerant leaks only when the cooling effect is poor. 　　 The motor will be frequently protected after overheating. Some users do not check the cause in depth, or even short circuit the thermal protector. After a short time, the motor will burn out.