Why does the compressor burn the motor? What is the cause of the burn-in phenomenon? The summary of the reasons for motor burn-in can be divided into: load, power supply, motor insulation, and lack of phase.
1. Common causes of compressor motor burning
1. Lack of phase
Reason: Generally, it is caused by the lack of phase of the power supply (one phase is not powered or the supply voltage is insufficient) or the contact point of the contactor in the line is not closed, the connection point of the wire is disconnected, loose or the contact position is oxidized.
Features: One or two phases (level 4) of the windings are all blackened, the coils are damaged symmetrically, and there are rules for lack of phases.
2. Overload
Reason: Generally, the motor runs with over-current for a long time, runs overheated, starts or brakes frequently, and also causes wrong wiring (delta connection into star connection).
Features: All the windings turn black, and the cable ties at the ends change color and become brittle or even broken.
3. Between turns
Cause: The enameled wire caused by the motor manufacturing process is broken, and the moisture, acid, and other corrosive substances in the system will also cause such failures.
Features: The winding is partially blown, usually when the inner cavity of the motor is clean, there is only one point of explosion.
4. Alternate
Cause: The interphase paper is not put in place, or the interphase paper (sleeve) is damaged.
Features: The motor burns out between two adjacent phases.
5. Ground strike
Reason: The distance between the coil and the end cover frame is not enough.
Features: There are traces of burnt black on the coil and the end cap or between the end caps.
2. Treatment method after the compressor burns out
1. If the compressor has been burned or mechanically malfunctioned or worn out, causing certain pollution to the refrigerant system, the situation is as follows (the system has a smell in the following situations, you can tell it by smelling it):
1. The residual refrigerated oil has been carbonized, contains acid, and is dirty in the tube.
2. After the compressor is dismantled, the original system pipes will be corroded with the air, causing condensation effect, increasing the residual water, and forming a dirty film after being corroded with the copper pipes and parts on the pipes, which will affect the operation after the next replacement of the compressor Function.
3. Abrasive copper, steel, and alloy dirt powder must have flowed into the pipeline to block some small tube channels.
2. The result after directly replacing the compressor with a new one without dealing with the system is as follows:
1. It is impossible to vacuum completely, and the vacuum pump is easily damaged. After adding new refrigerant, the refrigerant only plays the function of cleaning the system parts, and the pollution of the whole system still exists.
2. For new compressors and refrigeration oil, the refrigerant will be polluted immediately within 0.5-1 hour. After the refrigeration oil is impure, it will begin to destroy the original lubricating properties. Metal dust powder entering the compressor may break through the motor insulation film and cause a short circuit, and then burn it, resulting in increased friction between the shaft and the shaft sleeve or other moving parts, and the machine is seized.
3. After mixing refrigerant, oil, original pollutants, and acidic substances, more acidic substances and water content will increase, copper plating will start, mechanical clearance will decrease, and friction will increase to cause jamming.
4. If the original dryer is not replaced, it will release the original absorbed water and acidic substances. Acidic substances will slowly corrode the skin insulation film of the enameled wire of the motor.
Under the above conditions, the new compressor will be completely burnt out within about one month! !
Processing flow:
1. How to deal with a host refrigerant system whose compressor has burned out or failed? The compressor is damaged, of course it needs to be replaced, and it is very urgent, but before taking action to prepare the material tools, the following work should be done:
1. Check whether the contactor, overload device, and temperature controller in the control box have any quality problems. They must be checked until there is no problem.
2. Whether the various setting values have changed, and analyze whether the compressor is burned due to the change of the setting value or wrong adjustment.
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3. Check the abnormal condition on the refrigerant pipeline and correct it. Make sure the compressor is burnt or stuck, or half burned.
4. Measure the insulation with a megger, and measure the coil resistance with a three-purpose meter. Talk to the relevant personnel of the customer to understand the overview of the cause and effect, as a reference for judgment.
5. Try to release the refrigerant from the liquid pipe, observe the residue discharged from the refrigerant, smell its smell, and observe its color. (This article comes from the official account of Leng Nuan Encyclopedia. Warm reminder: After the compressor is burned, it will smell sour and sometimes pungent and spicy)
6. After dismantling the compressor, pour out a little refrigerated oil and judge the situation by observing its color. Before leaving the host, wrap the high and low pressure pipes with tape, or close the valve.
2. According to the above inspection work, there may be three types of compressor failures:
Situation 1: The motor of the compressor is not burned out, the current is normal, but the noise is loud. (Mechanical issues), the solution is as follows:
In this case, the oil does not smell bad, it is only polluted into powdery gray, which sinks inside the compressor, and the pollution in the system pipes is not obvious. Remove the original dryer, use nitrogen as much as possible to blow off the high-pressure end pipeline from the high-pressure end, and blow off the liquid pipe and parts of the low-pressure end in sections, and check whether the blown out is oil, dirt, or Moisture or other abnormalities and foreign objects.
After replacing with a new compressor, install a new dryer, and add nitrogen pressure to 10KG to detect leaks. If there is no leak, the remaining nitrogen will be discharged, and the high and low pressure ends will be evacuated at the same time. Add liquid refrigerant from the liquid pipe to reach 70%~80% of the refrigerant volume before starting the machine for testing. (The compressor must be warmed up for 2 hours)
Situation 2: The motor of the compressor is not burnt out, it can run, and the machine is in good condition, but the current is large and overloaded, and it is easy to trip. The treatment method is as follows.
In this case, the oil has a slight burnt smell and discoloration, and the system piping is relatively clean, but in systems where the metal surface has been acidified, the inner wall of the copper pipe turns red. After replacing with a new compressor, install a new dryer, and add nitrogen pressure to 10K to check for leaks. If there is no leak, vacuumize from the high and low pressure ends at the same time.
Add liquid refrigerant from the liquid pipe to reach 70%~80% of the refrigerant volume before starting the machine for testing. The compressor must be heated for 2 hours.
Attention must be paid to this situation. It is likely that the stability of the original power supply of the equipment and the possible load are too large, or the result of too frequent stop control. Refrigeration Encyclopedia recommends solving these problems, and the danger will always exist and cannot be completely resolved.
Situation 3: The motor of the compressor has been burnt out and cannot operate. The quality of the machine is unknown. The treatment method is as follows:
Method 1: The most serious situation is that the oil and refrigerant are smelly, burnt, spicy, and the oil is black like black ink. The inside of the tube is full of dirty black film and there will be water. Remove the desiccator and short-circuit this part with a copper pipe joint or a temporary detachable connection. Use a chemical pump to pump the cleaning agent into the pipeline system through the high-pressure pipe to clean the circulation flow.
Note: In case of severe pollution after the compressor burns out, the cleaning agent must be replaced if necessary and cleaned several times.
Method 2: Remove the dryer, and blow through the entire pipeline with high-pressure nitrogen gas of about 10KG. Replace the desiccator with a new one, detect leaks in the whole system, and evacuate from the high and low pressure ends at the same time.
Add liquid refrigerant from the liquid pipe to reach 70%~80% of the refrigerant volume before starting the machine for testing. Run for about half an hour after starting, replace the drier, and check its dirtiness. The second new drier must run for another 3 hours, observe the results, and replace it if necessary, until the system is completely clean. Finally, change the refrigeration oil of the compressor again, and observe the condition of the original new oil for the first time.
Note: When replacing the dryer above, the air should not enter the system again. In severe cases, the compressor must be removed for oil change, and all refrigerants must be released and replaced with new ones.
