Cold Storage High Voltage Protection Setting and Fault Traceability | Distinguishing High Temperature, Poor Heat Dissipation, and Excessive Refrigerant
High pressure protection is used to limit the maximum pressure on the condensing side, prevent the failure of condenser heat dissipation, excessive refrigerant filling, and pipeline blockage, which may cause the compressor housing to exceed the pressure limit and pose a risk of explosion.
R404A air-cooled low-temperature unit, with a normal high-pressure shutdown setting of 2.6MPa and a reset of 2.1MPa; The condensation temperature of the water-cooled unit is lower, and the high pressure protection setting value is lowered to 2.3 MPa.
The Xiteluo unit comes standard with high-voltage protection, which belongs to fast protection and generally does not have a delay. Once the pressure reaches the set value, it will immediately shut down to avoid safety risks.
The four root causes of high pressure alarms are poor heat dissipation in the condenser, excessive refrigerant filling, non condensable gases in the system, and throttling blockages in the exhaust pipeline. The investigation should be carried out in this order.
The system is mixed with non condensable air, and the condensation pressure is abnormally high. At the same time, the condensation temperature and pressure do not match. It is necessary to shut down and let it stand, and release air from the top of the condenser.
Many maintenance technicians add too much refrigerant at once, causing liquid refrigerant to fill the condenser volume, reducing the effective heat exchange area, continuously increasing pressure, and frequent high-pressure tripping.
Fan reversal, fan phase loss, and dirty fins are common causes of high pressure in air-cooled units. First, check the fan direction and air volume, then measure the pressure, and do not directly release fluorine.
The environmental temperature in foreign trade equatorial countries is above 40 ℃ all year round, and the high-pressure setting value cannot be directly copied from the temperate standard. At the same time, the condenser heat exchange area is reserved with a 15% margin for amplification.
High voltage protection strictly prohibits short-circuit shielding. High voltage loss of control can lead to pipeline joint leakage and compressor cylinder pressure exceeding the limit, which is a major safety hazard.
Priority should be given to investigating the cooling tower, water pump flow rate, and inlet water temperature of the water-cooled unit under high pressure. Aging of the cooling tower packing and uneven water distribution can directly increase the condensation pressure due to the inlet water temperature.
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FAQ
What is the standard high-pressure shutdown value for R404A air-cooled units? Shutdown at 2.6MPa, reset at 2.1MPa.
2. Is there a delay in high-voltage protection? Most of them have no delay and trigger an immediate shutdown.
What is the reason for the high condensation pressure and mismatched pressure and temperature? The system is mixed with non condensable air.
What high pressure performance will there be if there is too much refrigerant? The effective heat transfer area of the condenser decreases, causing a surge in pressure.
What is the first priority check for high voltage alarm? Condenser heat dissipation and fan operation status.
6. Can high-voltage protection be short circuited and forcibly operated? Short circuiting is strictly prohibited as there is a risk of pipeline rupture.
How to reserve excess space for the condenser in tropical projects? It is recommended to increase the heat exchange area by 15%.
