Compressor 9 types of faults and hazard analysis are all here! ! ! 1. Common faults of compressor — start with liquid Starting with fluid is a problem that easily occurs when the machine is stopped. During shutdown, the refrigerant will migrate from the system back to the compressor and deposit in the lubricant.
harm: Repeated migration of refrigerant will "wash" the oil film on the surface of mechanical parts; When the compressor starts with liquid, the lubricant will foam due to refrigerant evaporation, which will affect bearing lubrication, etc.
2.Common faults of the compressor-too much liquid returned Excessive refrigerant backflow is a problem that easily occurs in the operating state. It is the result of repeated excess refrigerant liquid migrating back to the compressor while the compressor is running. harm: The refrigerant liquid dilutes the lubricating oil, resulting in poor bearing lubrication.
Any system has the risk of excessive fluid return. Excessive fluid return may be caused by many different reasons, such as: Evaporator load is too small (excess liquid return often occurs under low load) Poor heat exchange efficiency of the heat exchanger (evaporator fan failure / too much oil in the evaporator, etc.) Defrost cycle Expansion valve selection is too large Expansion valve superheat control is unstable Superheat setting is low ... 3.Common faults of compressor-liquid return Liquid shock is the result of refrigerant liquid, or oil, or a mixture of refrigerant and oil, entering the vortex compression chamber. The abnormal force generated by the compressor fluid can cause damage to mechanical parts. Liquid strikes usually occur under liquid start conditions (excess refrigerant charge, large amounts of refrigerant migrate back to the compressor). For heat pump systems, liquid strikes usually appear in the defrost cycle.
The abnormal force generated by the compressor fluid can cause damage to the scroll (usually damage the scroll wall on the suction side), as well as damage to the cross slip ring. The liquid impact causes the mechanical parts to be damaged, and the generated metal debris enters the interior of the motor, which usually also causes the motor winding to short-circuit and burn.
4. Common failures of compressors-oil loss/oil shortage Loss of oil will cause insufficient oil in the compressor oil sump, and cannot guarantee the lubrication of bearings and other mechanical parts. This kind of fault phenomenon usually occurs in the case of poor oil return of the system, which will cause serious wear of all load bearing surfaces.
Poor oil return to the system can be caused by a variety of reasons: Compressor short cycle; Pipeline design causes oil to be trapped in the system and cannot be returned to the compressor; Refrigerant leakage; Long time low load or partial load operation; For long pipeline systems (pipe lengths greater than 20 meters), there is no proper oil supplement; The oil is trapped in the system due to other reasons, such as the clogged oil return hole of the steam, or the clogged filter, etc. 5. Common faults of compressors-high exhaust temperature The high discharge temperature is a failure caused by the actual operating conditions of the compressor exceeding the safe operating curve of the compressor. Due to the thermal expansion effect, the dynamic and static scrolls will squeeze each other under high exhaust temperature conditions, which will cause great contact stress. At the same time, due to the increase in temperature, the lubricating ability of the lubricating oil to the bearing will decrease. In addition, the motor stator may also be overheated and burned.
Typical causes of high exhaust temperature are usually: The actual operating conditions of the system exceed the safe operating range of the compressor, for example, the suction pressure is too low, or the discharge pressure is too high, or the pressure ratio is too large, or the suction superheat is too high, etc.; The system evacuation is not clean, there is air or other non-condensable gas; Poor heat exchange efficiency of the condenser, or failure of the condenser fan, or dirty fins of the condenser, etc.; The intake refrigerant flow rate is too low, it may be due to insufficient refrigerant charge, or the system is leaking, or the valve is not opened properly, etc.; 6. Common failures of compressors-high pressure ratio The high pressure ratio is a failure caused by the actual operating conditions of the compressor exceeding the safe operating curve of the compressor. Under the high pressure ratio, the extremely high pressure difference acts on the fixed scroll, which will cause damage to the top and side walls of the exhaust side of the scroll. The high pressure ratio can be the result of extremely low suction pressure, or extremely high discharge pressure, or a combination of both.
The increase in the pressure ratio will cause the exhaust temperature to increase synchronously, so the failure caused by the high pressure ratio is usually very similar to the failure caused by the high exhaust temperature. However, under extremely high compression ratios, the mechanical stress often causes more serious scroll mechanical damage.
7. Common faults of compressors-water, steam... System pollution is one of the main factors affecting the reliability of the system and the life of the compressor. This problem may cause a series of mechanical, electrical, and ice blockages in the compressor. Foreign pollutants are usually: Water (liquid in liquid state); Water vapor (not visible, high moisture content); Other incompatible materials, etc.
System contamination may be caused by system leaks. For example, evaporator leaks may cause chilled water to enter the system. In addition, many steps in the assembly process of the unit or the system maintenance process using the site may introduce dangerous foreign objects, and it is usually related to the control of cleanliness, such as: Insufficient system evacuation; The cleanliness of other components of the unit is poor; Poor refrigerant or lubricant quality is contaminated; Contamination of the system during the welding process, etc.
Refrigerant R22 is impure and mixed with unknown abnormal substances
8. Common faults of compressors-reverse Reversal is caused by the wrong phase sequence of the external power wiring. The reverse operation of the compressor will cause the temperature inside the low-pressure housing to rise (which may exceed 200°C) and cause the motor to overheat and burn. At the same time, the reverse rotation of the scroll will also cause mechanical damage to the scroll.
Long-term compressor reversal can cause a series of mechanical or electrical failures. Therefore, it is necessary to pay attention to whether the phase sequence is normal when the system is debugged. If an abnormal phenomenon occurs, the compressor may be in the reverse state: High and low pressure without pressure difference; The operating noise of the compressor is very abnormal, and there is obviously noise similar to metal friction; The temperature of the low-voltage housing rises quickly (the motor protector may trip).
9. Common faults of compressor-motor burned out Motor burning may be caused by a variety of reasons, the two main factors are: Mechanical failure Electrical failure. Most motor burns are caused by mechanical failures. In addition, electrical failure, such as abnormal power supply, is also the main cause of motor overheating and burning. 9.1. Foreign objects enter the stator of the motor and cause the short circuit of the enameled wire to burn: the foreign particles or metal debris generated by mechanical failures enter the motor and cause the short circuit of the enameled wire of the motor to burn. Potential reasons: Liquid impact (vortex cracking produces metal debris); Failures related to poor lubrication (metal debris from bearing wear); External foreign body pollution; Other mechanical damage; ... ...
9.2. Stator-rotor brooming causes the motor stator to burn out: during start-up or operation, the stator-rotor brooming will cause the motor to short-circuit and burn. Potential reasons: Main bearing wear due to poor lubrication (main bearing wear increases bearing clearance); The coaxiality of the rotor and stator is not good; … …
9.3 The motor stator winding coil is burned: Short circuit between motor windings ①; Short circuit between turns of motor winding ②; Short circuit at the stator slot exit ③; Short circuit in the stator slot ④; Coil short circuit ⑤; Short circuit at the lead terminal ⑥;
Potential reasons: Impurities and foreign objects damage the motor winding insulation layer; Peak voltage or surge current; Motor manufacturing defects; …; 9.4 The motor is evenly overheated and burned: The three-phase motor is evenly overheated and burned, which is usually caused by the excessively high stator current of the motor or insufficient cooling of the motor.
Potential reasons: Stalled, stuck cylinder; The voltage is too high or too low; Inspiratory pressure is too low; Motor overload; Compressors start and stop frequently in short cycle; …… 9.5. Three-phase voltage imbalance: Poor power connection; Unbalanced three-phase voltage of power supply;
Phase-deficient operation: star-shaped motors will cause two-phase windings to overheat and burn out under phase-deficient conditions, while one-phase windings are intact.
Potential reasons: The contactor contacts are poorly connected or stuck; The power connection is incorrect; … …；
