Aiming at the use of screw chiller units , some of the common fault problems that friends will encounter are high pressure faults, low pressure faults, low valve temperature faults, compressor overheating faults, communication faults, etc., but it is necessary to effectively solve these problems The main working principle of the screw chiller is linked first, and among them, the four processes of the refrigeration cycle are the most important. After the compressor is adiabaticly compressed, it becomes a high temperature and high pressure state. The compressed gas refrigerant is cooled and condensed in the condenser under constant pressure. After the condensation, it changes to a liquid refrigerant, which is then expanded to a low pressure by a throttle valve and becomes a gas-liquid mixture. Among them, the liquid refrigerant at low temperature and low pressure absorbs the heat of the material to be cooled in the evaporator, and becomes a gaseous refrigerant again. The gaseous refrigerant re-enters the compressor through the pipeline and starts a new cycle. After understanding the main working principle of screw chiller, we will analyze the common problems of screw chiller for you.
1. The high-pressure fault 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 1.40 ~ 1. 60MPa, and the protection value is set to 2.00MPa. If the pressure is too high for a long period of time, it will cause the compressor to run too much current, burn the motor easily, and damage the valve flaps of the compressor exhaust port. What should be done is to control the size of the compressor exhaust pressure within a safe range. Inside!
2. Low pressure failure The compressor suction pressure is too low, causing the low pressure protection relay to operate. 20MPa。 The compressor suction pressure reflects the evaporation pressure, the normal value should be 0.40 ~ 0. 60MPa, the protection value is set to 0. 20MPa. If the suction pressure is low, the return air volume will be small and the cooling capacity will be insufficient, resulting in a waste of electrical energy. Poor heat dissipation for the return air cooled compressor motor will easily damage the motor! The solution is the same as the high pressure fault, try to keep the compressor within the normal pressure range.
3． Low valve temperature failure The expansion valve outlet temperature reflects the evaporation temperature, which is a factor that affects heat transfer. Generally, the temperature difference between the outlet temperature of the expansion valve and the refrigerant water is 5.0 ~ 6.0 ° C. When a low valve temperature fault occurs, the compressor will stop. When the valve temperature rises, it will automatically resume operation. The protection value is -2.0 ℃.
4． Compressor overheat failure Thermistor is embedded in the compressor motor winding, and the resistance is generally 1kΩ. When the winding is overheated, the resistance value will increase rapidly. When it exceeds 141kΩ, the thermal protection module SSM will act and cut off the operation of the unit. At the same time, an overheating fault will be displayed and the TH fault indicator will be on.
5． Communication failure The computer controller's control of each module is realized through the communication line and the general interface board. The main cause of communication failure is the poor contact or disconnection of the communication line, especially the interface is affected by moisture and oxidation. In addition, the unit electronic board or The main interface board is faulty, the address dial switch is not selected properly, and a power failure can cause a communication failure.
The above five kinds of failure phenomena are the most common, and understanding these failure phenomena, judgment ability, and solutions has an irreplaceable effect on extending the service life of screw chiller!
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