How to solve the common erros in the operation of chillers?（二）
How to solve the common erros in the operation of chillers?
Industrial chillers will always wear out during use. Therefore, we need to record and analyze its operating parameters on a regular basis, listen to the sounds made during operation, check the use of snow and refrigeration oil, etc., and regularly maintain it Operation etc. Today we list the common problems and solutions in the operation of the chiller, hoping to help everyone.
- Communication failure
The computer controller controls each module through the communication line and the main interface board. The main cause of the communication failure is the poor contact or disconnection of the communication line, especially the interface is damaged due to moisture oxidation. In addition, the unit electronic board or the main interface Board failure, improper selection of address DIP switch, power failure can cause communication failure.
- Low voltage fault
The compressor suction pressure is too low, causing the low-pressure protection relay to operate. 2MPa。 The compressor suction pressure reflects the evaporation pressure, the normal value should be 0.4 ~ 0. 6MPa, the protection value is set to 0.2MPa. If the suction pressure is low, the return air quantity is small, and the cooling capacity is insufficient, which causes a waste of electrical energy. The heat dissipation of the compressor motor cooled by the return air is poor, and the motor is easily damaged.
The causes of low voltage failure are as follows:
(1) Insufficient refrigerant or leakage. If the refrigerant is insufficient and only partly leaks, the equilibrium pressure may be higher during shutdown, and the suction pressure after startup is lower, the discharge pressure is also lower, the compressor operating current is smaller, and the short running time reports a low pressure failure. The computer displays “LP CURRENT”, and the LP fault indicator of the unit electronic board is on. After a few seconds, the computer displays “LP RESET” and the LP fault indicator of the unit electronic board is off. If most of the refrigerant leaks, the equilibrium pressure is very low, and a low-pressure fault is reported at startup. If the inspiratory measurement pressure is less than 0.2 MPa, it cannot be started. The computer displays “LPCURRENT”, and the unit electronic board LP fault indicator lights. There is also a possibility that the refrigerant is sufficient, but the expansion valve opening is too small or blocked (or the refrigerant line is not smooth), may also cause low pressure failure. In this case, the balance pressure is often high, but the suction pressure is very low during operation, the discharge pressure is high, the compressor operating current is also large, and the valve temperature is also low, the expansion valve is frosted, and the pressure is long after shutdown To restore balance. This situation generally occurs during low-temperature operation or at the beginning of each year, and can return to normal after a period of operation.
(2) Insufficient refrigerant water flow rate, less heat absorption, poor refrigerant evaporation effect, and supercooled supersaturated steam, which is easy to produce wet compression, which is manifested as the pressure difference between the inlet and outlet water of the unit becomes smaller, the temperature difference becomes larger, and the suction temperature is lower , There is frost on the suction port. The cause of insufficient water flow is: there is air or water shortage in the system. The solution is to install an exhaust valve at a high place for exhaust; the pipeline filter is clogged or selected too thin, the permeability is limited, and a suitable filter should be selected And regularly clean the filter; the pump is selected to be smaller, not compatible with the system, the larger pump should be selected, or the backup pump should be enabled.
(3) The evaporator is clogged, the heat exchange is poor, and the refrigerant cannot be evaporated. The harm is the same as that of water shortage. The difference is that the pressure difference between the inlet and outlet water becomes larger, and the suction port also has frost. Therefore, the unit should be regularly inspected. Backwash.
(4) False alarm caused by electrical fault. Because the low-voltage protection relay is wetted, short-circuited, poorly contacted or damaged, the unit electronic board is wetted or damaged, and a false alarm caused by a communication failure.
(5) When the outside temperature is low, when the cooling water temperature is very low, the low-pressure fault will also occur when the machine is started; when the unit is running, due to insufficient preheating, the temperature of the refrigeration oil is low, the refrigerant is not fully separated, and a low-pressure fault will also occur . For the former case, measures such as closing the cooling tower and throttling cooling water can be taken to increase the cooling water temperature. In the latter case, the preheating time is extended, and the temperature of the refrigerating oil can generally return to normal after the temperature rises.
Three, high voltage failure
The compressor discharge pressure is too high, causing the high-pressure protection relay to operate. The compressor discharge pressure reflects the condensing pressure, the normal value should be 1.4 ~ 1.6MPa, and the protection value is set to 2.0MPa. If the pressure is too high for a long time, it will cause the compressor operating current to be too large, easy to burn the motor, and also cause damage to the compressor exhaust valve.
The causes of high voltage failure are as follows:
(1) The cooling water temperature is too high and the condensation effect is poor. The rated working condition of the cooling water required by the chiller is 30 ~ 35 ℃. The high water temperature and poor heat dissipation will inevitably lead to high condensing pressure. This phenomenon often occurs in high temperature seasons. The reason for the high water temperature may be: the failure of the cooling tower, such as the fan is not turned on or even reversed, the water distributor does not turn, which is manifested by the high temperature of the cooling water and rapid rise; the outside temperature is high, the water path is short, and the amount of water that can be recycled Less, in this case, the cooling water temperature is generally maintained at a high level, which can be solved by increasing the storage tank.
(2) The flow of cooling water is insufficient, and the rated water flow cannot be reached. The main performance is that the pressure difference between the inlet and outlet water of the unit becomes smaller (compared to the pressure difference at the beginning of the system), and the temperature difference becomes larger. The cause of insufficient water flow is the lack of water in the system or the presence of air. The solution is to install an exhaust valve at a high place for exhaust; the pipeline filter is clogged or selected too thin, the permeability is limited, and a suitable filter should be used. Clean the filter regularly; the pump is selected to be smaller and not compatible with the system.
(3) The condenser is fouled or clogged. The condensate is generally tap water, which is easy to scale when it is above 30 ℃, and because the cooling tower is open and directly exposed to the air, dust and foreign objects can easily enter the cooling water system, causing the condenser to be dirty and the heat exchange area is small , Low efficiency, but also affect water flow. The performance is that the pressure difference and temperature difference between the inlet and outlet water of the unit become larger, the temperature of the upper and lower sides of the condenser is very high, and the copper pipe of the condenser outlet is hot. The unit should be backwashed regularly, and chemical cleaning and descaling if necessary.
(4) Too much refrigerant charge. This situation generally occurs after maintenance, and the performance is that the suction and discharge pressure and balance pressure are both high, and the compressor operating current is also high. It should be deflated according to suction and discharge pressure and equilibrium pressure and operating current under rated working conditions until normal.
(5) Air, nitrogen and other non-condensable gases are mixed in the refrigerant. This situation usually occurs after maintenance and the vacuuming is not complete. It can only be drained, evacuated again, and refilled with refrigerant.
(6) False alarms caused by electrical faults. Because the high-voltage protection relay is damp, bad contact or damaged, the electronic board of the unit is damp or damaged, and the communication failure causes a false alarm. For this kind of false fault, the HP fault indicator on the electronic board is often not bright or bright, the manual reset of the high-voltage protection relay is invalid, the computer displays “HP RESET”, or it automatically disappears, the compressor operating current is normal, and the suction and discharge pressure normal.
Geson chiller product range covers Industrial Refrigeration and Commercial Central air-conditioning, including Water-cooled chillers, Air-cooled chillers, Screw chillers, Scroll chillers, Centrifugal chillers, Water(ground) source heat pumps, Air source heat pumps and etc., Capacity from 2tons~4000tons, and temperature from -160℃~30℃, complete full product series for customers.
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