Analysis of common failure causes of totally enclosed refrigeration compressor
Running end (R), starting end (S), common end (C), the resistance between RS is greater than that between SC and RC. The resistance between RS is equal to the resistance between SC plus the resistance between RC.
Using the above rules can be judged. It should be noted that the resistance value of the temperature rise tester of the terminal of the three-phase compressor is equal.
02 How to judge the short circuit of compressor motor winding?
Use a multimeter to select the resistance file. After zero adjustment, measure the resistance value of the compressor motor winding C-R or C-S. If the resistance value of the measured winding is less than the normal value, it can be judged that the winding is short-circuited.
Three-phase compressor:
The resistance value measured twice is infinite, indicating that there is a group of windings open circuit;
The three tests are infinity, indicating that at least two sets of windings are open;
Among the 3 measurements, 2 times the measured resistance value was significantly less than the other time, indicating that there is a short circuit.
03 How to judge whether the compressor motor touches the shell and is grounded?
Use the resistance file of the multimeter. Then hold a pen tightly to the common point, another table pen tightly on the exposed metal part of the compressor process tube, or support the small piece of paint on the shell plate to measure. If the resistance value is very small, it can be judged that the winding or internal wiring touches the shell through the ground.
04 How to judge the compressor motor winding is broken?
Adjust the multimeter to the resistance range, connect the test leads to the terminals of any 2 windings, and measure the resistance value. If the winding value is infinite, that is, there is no conduction between the terminals of the two windings, it can be judged that the winding is open.
05 Compressor does not start to check what?
Check whether the compressor overload, pressure switch, and overcurrent protector have tripped or damaged.
Check whether the indoor temperature sensor and the tube temperature controller are open or poorly connected, and whether there is a short circuit.
Check whether the relay is closed, whether the compressor is open or short circuit, and the compressor capacitance is bad.
06 What are the reasons for the compressor overheating, causing the shutdown immediately after starting?
Insufficient or excessive refrigerant, clogged capillary assembly, leaking inside the four-way valve.
The compressor itself is faulty, such as short circuit, open circuit, shell hitting the ground and so on.
High pressure is too high, the pressure relay is activated.
Poorly ventilated condenser or short-circuited airflow, or non-condensable gas in the system.
The ambient temperature of the outdoor unit is too high.
Compressor stuck cylinder or holding shaft.
07 Low compressor efficiency
Generally shows that the discharge pressure decreases, the suction pressure increases, and the temperature of the compressor cylinder head and the suction and discharge chambers is too high.
08 Judgement of compressor's loss of working ability
First test whether the suction port is inhaled, and then test whether the exhaust port is exhausted. Block the exhaust port with your hand. If you feel that the pressure is not very large, or even there is no exhaust, you can think that the compressor has lost its working capacity.
09 Why does the compressor motor have too much current?
Short circuit between the turns of the compressor, but did not reach the level of blown fuse. The "secondary friction" of the compressor destroys the smoothness of the friction surface, causing the power and current of the compressor to increase, but it has not yet reached the "shaft holding" or "clamping cylinder", which prevents the compressor from rotating.
Check the insulation resistance of the compressor to ground with a multimeter. Normally, it should be above 2MΩ. If it becomes smaller or close to zero, it means that it has been short-circuited. If the insulation resistance to ground is normal, check the resistance value of the starting and running windings. [Refrigeration Encyclopedia official source from this article] If there is a turn-to-turn short circuit, the operating current increases.
10 What is the reason for the difficulty of starting the three-phase compressor motor?
The power supply voltage is too low and the compressor motor winding is short-circuited.
11 How to eliminate the fault that the three-phase compressor motor slows down during operation, one-phase fuse blows, and one-phase current increases?
Is often caused by a contact between the compressor motor winding and the ground. After removing the ground wire, you can use a test pencil to test whether the case is live. If the casing is electrified, rewind the compressor motor winding or replace the compressor.
12 How to exclude the "single" sound of the three-phase compressor motor during operation?
The three-phase compressor motor emits a "speak" during operation, which is caused by the severe imbalance of the three phases. One phase power supply lacks the phase, and the three phases can be restored.
13 How to exclude three-phase compressor motor reverse rotation?
Is caused by a wiring error, and it is sufficient to exchange two wires in three phases at will.
14 Compressor replacement sequence and points of attention
R22 is a non-combustible gas, but when it comes into direct contact with a high-temperature flame, toxic gas will be generated. Therefore, the refrigerant in the refrigeration system is discharged before the welding operation.
R32 is a flammable and explosive refrigerant, and our Refrigeration Encyclopedia has repeatedly emphasized the characteristics of this refrigerant. Any R32 refrigeration equipment involved in the maintenance of the refrigeration system needs to be replaced, and it must be evacuated before operation! Be careful not to introduce fire sources!
R410A is low toxicity, non-combustible and non-explosive. When replacing the compressor, the compressor of R410A must be used, and the compressor of R22 must never be installed. When replacing the valve, there is a special mark on the R410A valve body.
15 What are the types of air conditioner compressor overload protector?
External overload protector; buried overload protector.
16 What is the protection of the compressor?
Overload protector: mainly used for overcurrent and overheat protection of compressor motor.
Internal protector: Mainly protect the compressor motor from overcurrent.
Thermal relay: mainly used for line overcurrent protection of three-phase compressor motor.
Inverter: It is mainly used in three-phase rotary compressors to prevent the reverse direction of compressor rotation or lack of phase energy.
17 What are the common causes of overload protectors?
The power supply voltage is too low and the symmetry of the three-phase voltage is poor.
Compressor motor runs at low speed for extended time.
Compressor motor long-term low-voltage operation with load.
Compressor motor cooling medium path is blocked.
The ambient temperature is too high.
18 What is the hydraulic blow of the compressor?
The refrigerant does not completely evaporate in the evaporator, causing the refrigerant to be sucked back by the compressor in wet vapor or liquid state, causing the compressor's liquid blow.
Liquid impact will cause the valve disc, valve plate, and piston to be damaged and damaged. In severe cases, the connecting rod may also be deformed, and even the compressor may be damaged.
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