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FAQ of refrigeration compressor

Views : 773
Author : sherry
Update time : 2020-11-02 14:01:40
1. Why control impurity and moisture content of compressor and air conditioning system?
 
When impurities enter the friction surface of moving parts in the compressor pump body, they will cause abnormal scratch and wear. If impurities enter the solenoid valve, expansion valve, control valve, capillary tube and stop valve in the air conditioning system, the valve hole will be blocked or the valve will not be closed tightly.
 
 The moisture in the compressor and air conditioning system will have adverse effects in several aspects
 
·The capillary tube and expansion valve will produce ice blockage, and the evaporator cooling pipe will also freeze;
 
·Metal materials are corroded to form deposits;
 
·The valve core is corroded and the valve is not closed tightly;
 
·The phenomenon of "copper plating" occurs on the surface of compressor pump parts;
 
·Accelerate the deterioration of insulation materials, refrigerant, refrigeration oil and other materials.
 
 2. What is the impact of low voltage on the air conditioning system?
 
If the voltage is too low, which is much lower than the specified service voltage range of the compressor, the locked rotor current value may not reach the action current specification of the protector, which will cause the protector to fail to act in time and cause the compressor motor to overheat or even burn out.
 
 3. What is the function and principle of compressor protector?
 
The main function of compressor protector is to protect the compressor from motor burnout and other accidents when the compressor is in abnormal condition.
Main principle: it depends on the internal heating wire of the protector and the internal resistance of the bimetallic sheet through the current heating and external conduction heat to make the bimetallic sheet act, so as to cut off the circuit and protect the compressor from damage.
 4. How to judge and deal with compressor failure?
 
Unable to start, no suction and exhaust pressure: first, check the compressor wiring and pipeline connection, check the main and auxiliary coil impedance, compressor insulation and withstand voltage and other basic items. If they are all normal, it is recommended to remove the compressor for idling test to see if there is suction and exhaust.
Suction and exhaust method is: when the compressor is running, press your finger on the exhaust port for a few seconds, and then release it to observe whether there is gas ejection, and a small amount of oil is ejected, which is a normal phenomenon. If there is suction and exhaust, the discharge pressure is large, indicating that the compressor can work normally, otherwise the compressor is not normal.
 5. Why is it necessary to prohibit the return of liquid refrigerant into the suction chamber of compressor?
 
If the liquid refrigerant directly enters the suction chamber of the compressor, the compressor volume will be smaller and smaller, and the pressure will rise sharply during the crankshaft rotation, which will lead to abnormal stress of pump body parts and valve plate, and even damage. Liquid hammer can also cause abnormal vibration and noise of compressor.
In addition, the liquid refrigerant will "wash" the lubricating oil on the surface of piston, blade and other parts after entering the cylinder, resulting in "running without oil", abnormal wear and even compressor shaft holding.
6. Why should the refrigerant recovery time of air conditioning not be too long?
 
The operating room for refrigerant recovery of air conditioner should not be too long. Because the refrigerant recovery time is too long, because the refrigerant gas inhaled is extremely thin, the exhaust temperature will be very high, causing the temperature of the pump body parts of the compressor to rise rapidly. When the temperature is too high, the difference of the expansion degree of each part is too large, and the fit gap of some parts becomes smaller or even disappears, resulting in abnormal scratch or wear.
 7. What is the effect of wrong connection of compressor? Why can't protectors protect?
 
The wrong wiring of compressor will make it unable to work normally. According to different wiring error modes, there will be stall, reverse rotation and stop after starting, which may lead to direct burning of compressor motor.
 Since the type selection of compressor protector is based on the working characteristics of the protector under abnormal working conditions when the compressor is connected correctly, it is impossible to ensure the protection of the compressor when connecting the wrong line. In the case of wrong wiring, it is difficult to protect the motor by protector.
 8. For the same system, do you need to adjust the system when changing compressors from different manufacturers?
 
Due to the different performance characteristics of compressors produced by different companies, the best performance can be shown only under the specific refrigerant flow rate, suction and discharge pressure, temperature and other conditions for a specific compressor.
 
Therefore, in the same air conditioning system, when using different compressors, it is better to adjust the system separately to ensure that the compressor used can work normally under the appropriate refrigerant flow, suction and discharge pressure and temperature conditions, so as to effectively extend the service life of the compressor and achieve the best use effect.
 9. Why is there a requirement for the coil temperature of compressor motor in operation?
 
It is determined by the insulation grade (insulation class: a (105 ° C), e (120 ° C), B (130 ° C), f (155 ° C), H (175 ° C)) and heat resistance characteristics of the insulation materials used for the compressor motor. For the motor enameled wire, too high temperature will lead to the reduction of cocoon weight, friction resistance K drop, easy peeling, insulation breakdown voltage and insulation impedance K drop, so as to greatly reduce the service life.
 
In addition, the motor temperature is too high, which can cause the polymer in the insulation material to dissolve too much, these substances will precipitate and gather in some places in the system or compressor exhaust port, which will affect the performance of compressor and system. In addition, the coil temperature is too high will cause the compressor motor efficiency to be reduced.
 
10. Why can the compressor be started again after shutdown for at least 3 minutes?
 
When the compressor starts, more refrigeration oil will enter the air conditioner system along with the refrigerant circulation. If there is not enough operation time, the refrigeration oil will not be able to return to the compressor cavity in time. If the compressor is often started and stopped soon, the internal oil level of the compressor will be low, which is easy to cause poor lubrication of the mechanical moving parts of the compressor.
In addition, the shutdown time of more than 3 minutes is mainly to give the system enough pressure balance time, otherwise, due to the existence of high and low pressure, the compressor can not start normally.
 11. Why can't the compressor operate in "vacuum condition"?
 
The so-called "vacuum condition" is not an absolute vacuum state, but an extremely low pressure state. Gas molecules will ionize at very low pressure.
 
According to the actual experimental results, the breakdown voltage of compressor terminal is the lowest when the compressor internal pressure is about 3.5mmhg. When the compressor is energized, it is easy to cause breakdown and internal carbon deposition, which will damage the insulation of the sealing terminal. When the compressor is tight, the sealing terminal will burn out and fly out. Therefore, it is necessary to avoid energizing in the vacuum state of the compressor.

 
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