Analysis of common causes of overcurrent and burnout in refrigeration compressors

1、 Common causes of compressor overcurrent
（1） Poor heat dissipation of the external unit
External unit return and exhaust short circuit: The installation position of the external unit plays a key role in the heat dissipation effect. If the outdoor unit is installed in a closed balcony, narrow aisle, or poorly ventilated indoor area, and there are obstacles in front of the air outlet, it will cause a short circuit in the return and exhaust air. For example, in some old residential areas, users install outdoor units in the corners of balconies in order to save space, surrounded by debris, which makes it difficult for air to circulate properly and heat to be effectively dissipated, thereby affecting the normal operation of compressors and causing overcurrent problems

Low air volume and slow heat dissipation speed of the external unit: If the condenser of the external unit is severely blocked by dust or oil, or if the fan motor speed slows down, the fan capacitance decreases, or if the ambient temperature around the external unit is too high, the air volume of the external unit will decrease and the heat dissipation speed will slow down. Taking condenser dust accumulation as an example, during long-term use, a large amount of dust will accumulate on the surface of the condenser, like wrapping a layer of "cotton quilt" around the condenser, which hinders the dissipation of heat and requires the compressor to work harder to maintain the cooling effect, thereby increasing the current and causing overcurrent..

（2） External power supply voltage factor
Abnormal power supply voltage: Low or high power supply voltage can cause high working current of the compressor. In China, low voltage is quite common, especially during peak electricity consumption periods. When the power supply voltage (i.e. the voltage before startup) is too low, it is recommended that the user rewire. If the voltage is around 190V, it is possible to consider installing a voltage regulator, but if the voltage is too low, installing a voltage regulator may not achieve the desired effect.
（3） Refrigeration system malfunction
Mixing air into the refrigeration system: If air is mixed into the refrigeration system, it often accumulates in the upper part of the condenser because it cannot pass through the condenser's accumulator. To determine whether there is air in the system, it is generally possible to observe the fluctuation of system pressure. If there is air in the system, it should be evacuated and fluorinated again to ensure the normal operation of the refrigeration system.
（4） High shell/internal temperature
Poor lubrication of compressor: If the height difference between indoor and outdoor units is greater than 5 meters but no oil return bend is made, or only one oil return bend is made on one pipe, the system will not be able to return oil smoothly. Due to lack of lubrication, the temperature of the compressor will gradually rise during operation, ultimately leading to overheating and tripping. For example, in some high-rise buildings, due to improper installation, there is a large height difference between indoor and outdoor units and inadequate oil return measures, resulting in poor lubrication of the compressor and frequent overheating and tripping.

Excessive impurities and moisture in the system: Excessive impurities and moisture in the system can cause the lubricating oil to deteriorate, carbonize, and fail to exert normal lubrication effects, resulting in a sharp rise in compressor temperature and overheating tripping. This situation usually occurs on machines that have been repaired or have been in use for a long time. Check the substance in the system, if it appears black, then the situation must exist. At this point, nitrogen should be used to clean the system, replace the compressor and capillary components, and evacuate and fluorinate again.
（5） Poor cooling effect of compressor
When the fluorine in the system is too low, the temperature of the compressor during operation will be very high. High temperature coils mainly rely on refrigerant suction for cooling. If there is too little fluorine, the system flow rate will be small, leading to an increase in suction superheat. In addition, the low suction flow rate of the compressor greatly reduces the cooling efficiency, and prolonged operation can lead to thermal protection of the compressor.

Shanghai KUB Refrigeration Equipment Co., Ltd.

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