Common causes and treatment methods of compressor oil pressure difference alarm

July 24, 2023

When the oil supply system of the refrigeration compressor fails, in order to avoid the transmission parts of the refrigeration compressor from burning out, it is generally equipped with an oil pressure difference controller, which is particularly necessary to install an oil pressure difference controller in a high-speed refrigeration compressor. The oil pressure difference controller can automatically cut off the power supply and stop the refrigeration compressor through the difference between the lubricating oil pressure and the suction pressure of the refrigeration compressor after a certain period of time. The differential pressure controller with thermal delay is usually used for oil pressure difference. After the controller acts once, it can only be started again after the thermal element is completely cooled and manually reset.


When installing the oil pressure differential controller, the general high and low pressure interfaces are respectively connected with the oil pressure at the oil pump outlet and the low pressure in the crankcase. The controller body should be installed vertically, with the high pressure port at the bottom and the low pressure port at the top. The oil pressure difference is equal to the difference between the reading of the oil pressure gauge and the reading of the suction pressure gauge. Don't mistake the digital reading of the oil pressure gauge for the oil pressure difference. Generally, the set value of the oil pressure difference of the semi-sealed piston compressor is 0.15 ~ 0.3MPa.


There are several common reasons for oil pressure difference alarm:


1. The oil level in the system is insufficient due to insufficient frozen oil, which causes the oil pump to suck oil normally;

2. The oil in the system is too dirty, causing the filter of the oil pump to be blocked;

3. The relay with poor oil pressure is insensitive to work;

4, The oil pump itself fails to absorb oil;

5. A large amount of refrigerant is mixed in the freezing oil, which makes the oil pressure unable to be established;

6, Compressor liquid, crankcase liquid refrigerant is too much; Adjust the expansion valve and check the oil heating.

7, Crankcase oil temperature is too low.


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Processing method of oil pressure difference alarm:

1. If the refrigerating oil is not enough, you only need to replenish lubricating oil to the standard oil level of the sight glass;

2. If the lubricating oil is too dirty, you need to take out the filter, clean it and replace it with new refrigerant oil. 3. Replace the new oil pressure differential relay;

4. If the oil pump fails, a new oil pump needs to be replaced in time;

5. Heat the crankcase to separate the refrigerant in the lubricating oil, or let off the refrigerant in the compressor;

6. Find out the reason for excessive liquid return;

7, need to check the oil heater.


In practical application, it is a common phenomenon that the oil filter is dirty and blocked. In this case, we can solve this problem by cleaning the filter or replacing the frozen oil.


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