Causes and solutions for high pressure failure of chillers
Column:Industry News Time:2018-10-24
The high pressure failure of the chiller means that the compressor discharge pressure is too high, resulting in the action of the high voltage protection relay. The compressor discharge ...

The high pressure failure of the chiller means that the compressor discharge pressure is too high, resulting in the action of the high voltage protection relay. The compressor discharge pressure
reflects the condensing pressure. The normal value should be 1.4~1.8MPa, and the protection value setting should not exceed 2.0MPa. Because the long-term pressure is too high, it will lead to
excessive operating current of the compressor, which will easily burn the motor and cause damage to the compressor.


What is the main cause of high pressure failure in chillers?

1. The refrigerant is filled too much.

This situation generally occurs after maintenance, which is characterized by high suction and discharge pressure, equilibrium pressure, and high operating current of the compressor.


Solution

: The refrigerant should be discharged under the rated working conditions according to the suction and exhaust pressure and the equilibrium pressure and the operating current until normal.


2. The cooling water temperature is high and the condensation effect is poor.

The rated working condition of the cooling water required by the chiller is 30~35°C, the water temperature is high, and the heat dissipation is bad, which will inevitably lead to high condensing
pressure. This phenomenon often occurs in the high temperature season.


Solution:

The reason for the high water temperature may be the cooling tower failure. If the fan is not turned on or even reversed, the water distributor does not turn. The cooling water temperature is
high and rises rapidly. The outside air temperature is high, the water path is short, and the circulating water is small. In this case, the cooling water temperature is generally maintained at a high
level, and it can be solved by increasing the storage tank.


3. The cooling water flow is insufficient, and the rated water flow rate is not reached.

. The main performance is that the pressure difference between the unit inlet and outlet water becomes smaller (compared with the pressure difference at the beginning of the system operation),
and the temperature difference becomes larger.


Solution

: The pipeline filter is clogged or selected too fine, and the water permeability is limited. The appropriate filter should be selected and the filter should be cleaned regularly; or the pump should be
selected to be small and not compatible with the system.


4. Condenser fouling or blockage.

The condensed water is generally tap water. It is easy to scale when it is above 30 °C. Because the cooling tower is open, it is directly exposed to the air. The dust foreign matter can easily enter the
cooling water system, causing the condenser to be blocked and the heat exchange area is small. It is inefficient and affects water flow. The performance is that the pressure difference between the
inlet and outlet water of the unit is large, and the temperature difference between the upper and lower sides of the condenser is high. The copper tube of the condenser is hot.


Solution:

The unit should be backwashed regularly and chemically cleaned as necessary.


5. False alarms caused by electrical faults.

Due to the moisture, poor contact or damage of the high voltage protection relay, the unit electronic board is damp or damaged, and the communication failure causes a false alarm.


Solution:

This kind of false fault, often the HP fault indicator on the electronic board is not bright or slightly bright, the high voltage protection relay manual reset is invalid, the compressor running current
is normal, and the suction and exhaust pressure is also normal.


6. The refrigerant is mixed with non-condensable gases such as air and nitrogen.

There is air in the refrigeration system. In many cases, when the air is very much, the pointer of the high voltage meter will be very shaken.


Solution

: This situation usually occurs after maintenance, and the vacuum is not complete. After stopping, it can be emptied at the high point of the condenser or re-vacuum and added with refrigerant.


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