1. Oil shortage and insufficient lubrication of compressor
When the scroll compressor is working, a large amount of refrigerant gas is discharged and a small part of lubricating oil is carried away. Short time oil shortage of the compressor will cause abnormal wear of all relevant components inside the compressor, resulting in large vibration and noise; Long time oil shortage will cause overheating of internal related components, resulting in bearing sintering, shaft clamping, compressor built-in protection, exhaust or top temperature protection, over-current protection, power supply air switch tripping, abnormal compressor operating sound, excessive temperature of compressor chamber, etc.
reason:
1. The compressor starts and stops frequently for a long time.
2. The system contains air or moisture.
3. System return liquid or refrigerant migration dilutes lubricating oil.
4. The compressor reverses (in case of wrong phase sequence).
5. The refrigerant leakage of the system makes the compressor lubricating oil less.
6. There are other chemicals in the system, which will deteriorate the lubricating oil after chemical reaction with the lubricating oil.
2. Compressor liquid hammer
When a large amount of liquid returns from the scroll compressor, the liquid droplets will have a great impact on the vortex disk during the compression process, which may break the vortex disk; The viscosity of lubricating oil containing a large amount of liquid refrigerant is low, and it can not form enough oil film on the friction surface, resulting in rapid wear of moving parts inside the compressor; The refrigerant in the lubricating oil will boil when it is heated during transportation, affecting the normal transportation of lubricating oil. The fragments of the scroll disk after the liquid strike fall on the coil, damaging the coil insulation layer, which may result in current protection or the built-in protection of the compressor may not act.
reason:
Too much refrigerant is added, resulting in a large amount of liquid return in the system.
The internal fan does not rotate and the air volume is small, resulting in incomplete refrigerant evaporation.
When the power is off, the EXV valve remains open to a certain extent, causing a large amount of liquid return to the system.
Too much oil is added, resulting in system oil hammer (low pressure chamber compressor).
3. Compressor burned out at high temperature
The high temperature and overheating of the scroll compressor are characterized by exhaust or top temperature protection, excessive temperature of the compressor chamber, and high pressure protection. Long term high temperature overheating will not only reduce the insulation performance and reliability of the motor, but also shorten the life of the motor; Moreover, it will also reduce the lubricating capacity of the lubricating oil, and even cause the carbonization and acidolysis of the lubricating oil.
After acid hydrolysis, the lubricating oil will cause copper plating. After copper plating, the fine metal scraps generated by wear will be mixed in the lubricating oil, which on the one hand weakens the lubricating effect of the lubricating oil; On the other hand, small metal chips gather in the motor winding due to magnetism, forming a conductive circuit, causing partial discharge or coil short circuit.
reason:
The system vacuum is not enough.
Too little refrigerant is added or refrigerant leaks.
Ice blockage of the system air return pipe causes excessive exhaust or top temperature.
If the connecting pipe is too long or the pipe diameter is small, the system resistance will increase, resulting in the increase of exhaust temperature and pressure.
4. Compressor motor damaged
The damage of the scroll compressor motor is mainly manifested in the damage (short circuit) and open circuit of the stator winding insulation. After the winding is burnt, some phenomena or direct causes leading to the burning are covered up, making it difficult to analyze and investigate the causes afterwards. The faults are as follows: frequent closing or burning of the contactor, over-current protection or built-in protection of the compressor, tripping of the power switch, excessive temperature of the compressor chamber, etc.
reason:
The contact of the contactor is burnt or abnormal, such as phase loss and phase deviation.
The rated voltage of the power supply shall not exceed ± 10%.
The unbalance rate of three-phase voltage shall not exceed 3%.
The load current under unbalanced voltage is 4-10 times that under normal operation.
All the above reasons may cause the worn metal chips to damage the insulation layer of the coil and burn the motor.
Insufficient motor cooling, large refrigerant leakage or low evaporation pressure will reduce the system mass flow, making the motor unable to get good cooling.
