The reasons for the high pressure failure of the screw chiller are as follows

The discharge pressure of the screw chiller compressor 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, the motor is easy to burn, and it is easy to cause damage to the compressor exhaust valve. The reasons for the 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 screw chiller is 30~35℃. 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: cooling tower failure, such as the fan is not turned on or even reversed, the water distributor does not turn, it is manifested as the cooling water temperature is very high, and it rises rapidly; the outside temperature is high, the water path is short, and the amount of water that can be circulated In this case, the temperature of the cooling water is generally maintained at a relatively high level, which can be solved by increasing the storage tank.

(2) The cooling water flow is insufficient and cannot reach the rated water flow. The main performance is that the pressure difference between the inlet and outlet water of the unit becomes smaller (compared with the pressure difference at the beginning of the system is put into operation), and the temperature difference becomes larger. The reason for the 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 the height of the pipeline to exhaust; the pipeline filter is blocked or the selection is too fine, and the water permeability is limited. You should choose a suitable filter and Clean the filter regularly; the water pump is small and does not match the system.

(3) The condenser is fouled or blocked. Condensate water is generally tap water. It is easy to scale when the temperature is above 30℃. Because the cooling tower is open, it is directly exposed to the air. Dust and foreign matter can easily enter the cooling water system, causing the condenser to be dirty and blocking and the heat exchange area is small. , The efficiency is low, and it also affects the water flow. The performance is that the pressure difference and temperature difference between the inlet and outlet water of the unit become larger, the upper and lower temperatures of the condenser are very high when the condenser is touched by hand, and the condenser outlet copper pipe is hot. The screw chiller should be backwashed regularly, and chemical cleaning and descaling should be carried out if necessary.

(4) The refrigerant is overcharged. This situation generally occurs after maintenance, and it is manifested as high suction and exhaust pressure and balance pressure, and high compressor operating current. It should be vented according to the suction and discharge pressure, balance pressure and operating current under rated conditions until normal.

(5) Non-condensable gases such as air and nitrogen are mixed in the refrigerant. This situation generally occurs after maintenance, and the vacuum is not complete. It can only be drained, re-evacuated, and refilled with refrigerant.

(6) False alarms caused by electrical faults. Because the high-voltage protection relay is damp, poorly contacted or damaged, the unit electronic board 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 off or slightly bright, the high-voltage protection relay is invalid manually reset, the computer displays “HP RESET”, or disappears automatically, the running current of the compressor is normal, and the suction and discharge pressure is also normal.