Analysis of Frequently Asked Questions about Refrigeration Compressors
1. Why should we control the impurity content and moisture content of compressors and air conditioning systems?
Impurities entering the friction surfaces of the moving parts in the compressor pump body will cause abnormal scratches and wear. Impurities entering the solenoid valves, expansion valves, control valves, capillary tubes and stop valves in the air conditioning system will block the valve holes or cause the valves to not close tightly. Invalid.
Moisture in compressors and air conditioning systems will have several adverse effects:
The capillary tube and expansion valve will cause ice blockage, and the evaporator cooling tube will also freeze;
Metal materials are corroded and deposits are generated;
The valve core is corroded and does not close tightly;
"Copper plating" occurs on the surface of compressor pump body parts;
Accelerate the deterioration of insulation materials, refrigerants, refrigeration oil and other materials.
2. What impact will low voltage have on the air conditioning system?
If the voltage is too low, much lower than the specified operating voltage range of the compressor, the locked-rotor current value may not reach the operating current specification of the protector, which will cause the protector to be unable to act in time, causing the compressor motor to overheat or even burn out. .
3. What is the function and principle of the compressor protector?
The function of the compressor protector is mainly to protect the compressor from accidents such as motor burnout when it is in abnormal conditions. The internal heating wire of the protector and the internal resistance of the bimetallic sheet cause the bimetallic sheet to operate through current heating and external heat conduction, thereby cutting off the circuit and protecting the compressor from damage.
4. How to make basic judgment and treatment after compressor failure?
Unable to start, no suction and exhaust pressure: First check the compressor wiring and pipeline connections, check the main and auxiliary coil impedance, compressor insulation withstand voltage and other basic items. If everything is normal, it is recommended to remove the compressor and run it idling to check whether there is suction and exhaust.
The suction and exhaust method is: when the compressor is running, press your finger on the exhaust port for a few seconds, then release it and observe whether there is gas spraying out. It is normal for a small amount of oil to spray out. If there is suction and exhaust, and the exhaust pressure is large, it means the compressor can work normally, otherwise the compressor is not normal.
5. Why is it necessary to prohibit the backflow of liquid refrigerant into the suction chamber of the compressor?
If the liquid refrigerant directly enters the suction chamber of the compressor, the compressor volume will become smaller and smaller during the rotation of the crankshaft, and the pressure will rise sharply, causing abnormal stress on the pump body parts and valve plates or even damage. Liquid slugging can also cause abnormal vibration and noise in the compressor.
In addition, after the liquid refrigerant enters the cylinder, it will "wash away" the lubricating oil on the surface of the piston, blades and other parts, causing the equivalent of "oil-starved operation", abnormal wear and even causing the compressor shaft to lock.
6. Why should the refrigerant recovery time of air conditioners not be too long?
The time between refrigerant recovery operation of the air conditioner should not be too long. Because after the refrigerant recovery time is too long, the exhaust temperature will be very high because the inhaled refrigerant gas is extremely thin, causing the temperature of the pump components of the compressor to rise rapidly. Excessively high temperature will cause the expansion degree of each part to be too different, causing the fitting gap of some parts to become smaller or even disappear, eventually causing abnormal scratches or wear.
7. What is the impact of wrong wiring of the compressor? Why can't the protector protect?
If the compressor is connected incorrectly, it will not work properly. Depending on the wrong wiring method, the compressor may be blocked, reversed, stopped after starting, etc., and it is very likely to cause the compressor motor to be burned directly.
Since the compressor protector is selected based on the working characteristics of the protector under abnormal working conditions when the compressor is correctly wired, it cannot ensure that the compressor is protected when the wrong wires are connected. In the case of incorrect wiring, it is difficult to protect the motor through a protector.
8. In the same system, do I need to adjust the system when replacing a compressor from a different manufacturer?
Since the performance characteristics of compressors produced by different companies are different, a specific compressor will only show the best performance under specific conditions such as refrigerant flow, suction and exhaust pressure, and temperature.
Therefore, when using different compressors in the same air conditioning system, it is best to adjust the system separately to ensure that the compressor used works normally under appropriate refrigerant flow, suction and exhaust pressure, and temperature conditions, so that it can effectively extend the extend the service life of the compressor and achieve the best results.
9. Why is there a requirement for the compressor motor coil temperature during operation?
Insulation grade of the insulation material used in the compressor motor (insulation grade: A(105°C), E(120°C), B(130°C), F(155°C), H(175°C)) and heat resistance characteristics. For motor enameled wires, excessive temperature will lead to a reduction in the amount of film cocoons, a K drop in friction resistance, easy peeling, a K drop in insulation breakdown voltage and insulation resistance, etc., thus greatly reducing the service life.
In addition, excessive temperature of the motor can cause excessive dissolution of polymers in the insulating material. These substances will precipitate and accumulate somewhere in the system or at the compressor exhaust port, thus affecting the performance of the compressor and system. Also, if the coil temperature is too high, the efficiency of the compressor motor will decrease.
10. Why does the compressor need to be shut down for at least 3 minutes before it can be started again?
When the compressor starts, more refrigeration oil will enter the air conditioner system along with the refrigerant circulation. If there is not enough running time, the refrigeration oil will not be able to return to the compressor cavity in time. Frequent startup and shutdown soon will cause internal damage to the compressor. Low oil level can easily cause poor lubrication of the mechanical moving parts of the compressor. In addition, the downtime of more than 3 minutes is mainly to give the system enough pressure balance time, otherwise the compressor will not start normally due to the existence of high and low pressures.
