Reason 3 for causing excessive operating current of the compressor in the high and low temperature test chamber: lack of refrigeration oil in the compressor
Today, we will continue to explain the third reason for the overcurrent of the compressor in the high and low temperature test chamber. Firstly, the compressor lacks refrigeration oil;
1、 High shell/internal temperature:
1. Poor lubrication of the compressor in the high and low temperature test chamber: If the height difference between indoor and outdoor units is greater than 5 meters, no oil return bend is made, or only an oil return bend is made on one pipe, the system cannot return oil smoothly. The compressor gradually rises in temperature during operation due to lack of lubrication, which later leads to overheating and tripping. For example, when the outdoor unit is located below and in heating operation, the gaseous working fluid flows inward in the coarse tube, while the liquid working fluid flows downward in the fine tube, resulting in poor oil return. The outdoor unit is located above, and the heating system is running. The gaseous working fluid flows downward in the coarse tube, while the liquid working fluid flows in the fine tube, resulting in better oil return. When cooling, the situation is opposite to the previous one. There are two types of return bends: shaped and S-shaped. The S-shape can be added to the middle part of the connecting pipe, and the shape is generally close to the machine installation. The radius should be as small as possible.
2. Impurities and excessive moisture in the high and low temperature test chamber system can cause the lubricating oil to deteriorate, carbonize, and fail to function properly, resulting in a sharp increase in compressor temperature and overheating induced tripping. This situation usually occurs on repaired high and low temperature test chambers or equipment that has been used for a long time. If the substances in the inspection system show color, it is certain that this situation exists. At this time, nitrogen should be used to clean the system, replace the compressor and capillary components, and evacuate and fluorinate again.
3. Air conditioning is often used in environments below 0 degrees Celsius: When the compressor in the high and low temperature test chamber starts, the lubricating oil inside bubbles, causing a large amount of lubricating oil to instantly flow out of the compressor. At this time, no matter how well the system is designed, the speed of oil return is much lower than the speed of oil discharge. The lack of lubrication in the compressor causes temperature rise and overheating protection. In this situation, an oil heater (40W-60W, 220V) should be installed on the compressor. When the compressor stops, the oil heater should continue to be powered on. The connection method is to connect the oil heater in series with the normally closed switch of the contactor, and then connect it to the fire and neutral wires of the power supply.
2、 The cooling effect of the compressor in the high and low temperature test chamber is poor. The system has too little fluorine, and the temperature of the compressor is very high during operation. The high-temperature coil is cooled by the refrigerant sucked in. If the fluorine is too low, the system flow rate will be small, which cannot meet the load of the evaporator 100, resulting in an increase in suction superheat. In addition, the low suction flow rate of the compressor greatly reduces the cooling efficiency. This long-term operation can cause the compressor to overheat: protection.