Water chillers are also called freezers, refrigeration units, ice water units, cooling equipment, etc. Because they are widely used in various industries, the requirements for water chillers are different. In the refrigeration industry, it is divided into air-cooled chillers and water-cooled chillers, and the chillers are divided into low-temperature chillers and normal-temperature chillers in temperature control.
High-voltage fault of water chiller means that the compressor exhaust pressure is too high, which leads to the action of high-voltage protection relay. Compressor exhaust pressure reflects condensation pressure, and the normal value should be 1.4~1.8MPa, and the protection value should not exceed 2.0MPa. Because the long-term pressure is too high, the compressor running current will be too high, resulting in compressor damage.
Common causes of high voltage faults:
1. The cooling water temperature is high and the condensation effect is poor.
The rated working condition of cooling water required by chillers is 30~35℃. High water temperature and poor heat dissipation will inevitably lead to high condensing pressure, which often occurs in high temperature season.
The reason for the high water temperature may be the failure of the cooling tower, for example, the fan is not turned on or even reversed, and the water distributor does not turn, which shows that the cooling water temperature is very high and rises rapidly; The external air temperature is high, the waterway is short, and the amount of recyclable water is small. In this case, the cooling water temperature is generally maintained at a high level, which can be solved by adding water storage tanks.
2. The cooling water flow is insufficient, which can not reach the rated water flow.
The main performance is that the pressure difference between inlet and outlet water of the unit decreases (compared with the pressure difference at the beginning of the system operation), and the temperature difference increases. The reason for the insufficient water flow is the lack of water or air in the system. Exhaust valves can be installed at high places of pipelines for exhaust. The filter is blocked or selected too fine, and the water permeability is limited. Appropriate filters should be selected and the filter screen should be cleaned regularly. The water pump is small and does not match the system.
3. Condenser fouling or blockage.
Generally, tap water is used for condensed water, which is easy to scale when the temperature is above 30℃. Moreover, because the cooling tower is open and directly exposed to the air, dust and foreign matter can easily enter the cooling water system, causing dirty blockage of the condenser, small heat exchange area and low efficiency, and also affecting the water flow. Its 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 touched by hand, and the outlet copper pipe of the condenser is hot. The unit shall be backwashed regularly and chemically cleaned and descaled when necessary.
4. Excessive refrigerant charge.
This situation usually occurs after maintenance, which shows that the suction and exhaust pressure and equilibrium pressure are both on the high side, and the compressor running current is also on the high side. Under rated working conditions, bleed air according to suction and exhaust pressure, equilibrium pressure and operating current until it is normal.
5. The refrigerant is mixed with non-condensable gases such as air and nitrogen.
This situation usually occurs after maintenance, and the vacuum pumping is not complete. It can only be drained, vacuumed again and refilled with refrigerant.
6. False alarm caused by electrical fault.
6.1 Due to damp, poor contact or damage of the high-voltage protection relay, damp or damage of the electronic board of the unit, the communication failure causes false alarm.
Solution: This kind of false fault, often the fault indicator light is not bright or slightly bright, the manual reset of the high voltage protection relay is invalid, the running current of the compressor is measured normally, and the suction and exhaust pressure is also normal.
6.2 The cooling water flow is insufficient, which can not reach the rated water flow. The main performance is that the pressure difference between inlet and outlet water of the unit decreases (compared with the pressure difference at the beginning of the system operation), and the temperature difference increases.
Solution: The pipeline filter is blocked or selected too fine, so the water permeability is limited. Appropriate filters should be selected and the filter screen should be cleaned regularly. Or the water pump is selected to be smaller and not matched with the system.
The refrigeration system has air. When the water chiller works, the pressure gauge shakes, indicating that there is air in the system.
Solution: It is necessary to vacuumize again, and replace the drying filter when necessary, so as to completely eliminate the moisture in the refrigeration system. This situation usually occurs after maintenance, and the vacuum pumping is not complete. After shutdown, the condenser can be emptied at the highest point or vacuumized again to add refrigerant.