Phase sequence, phase loss, and reverse phase protection
Phase sequence, phase loss, and reverse phase protection are common electrical protection measures used to ensure the normal operation of electrical equipment and systems.
Fault Analysis
Use a multimeter to check whether there is 380V voltage between each phase of the three-phase power supply entering the circuit board. If there is, the fault may be due to reverse phase protection; swapping any two adjacent input lines of the power supply connected to the generator set can resolve it. Otherwise, the fault may be due to missing phase protection; check whether the connected power supply or input lines are reliable. This fault can also occur after power grid maintenance or when the power quality of self-contained generator equipment is poor (the voltage between phases of the power supply should be within the range of 380V ±10%).
Flow protection
effective measure taken to ensure the normal operation of equipment or systems, which can prevent equipment damage or other problems caused by insufficient or abnormal water flow.
Fault analysis
Check whether the water flow switch is working normally; for units without a water flow switch, check whether the bypass wire is normal;
Overheat protection for water outlet
Over-temperature protection for water discharge is a safety protection mechanism. When the water discharge temperature exceeds the set safe range, the over-temperature protection mechanism will activate to prevent the equipment from overheating and being damaged, and at the same time to prevent users from being injured by excessively hot water.
Fault Analysis
Whether the actual temperature of the water tank exceeds the set temperature; the water tank sensor is placed incorrectly or the water tank sensor is not in close contact with the blind tube wall; the water tank temperature sensor wiring is broken or the temperature sensor resistance has drifted.
Overvoltage protection
High-pressure protection is usually monitored by a pressure sensor in the system. When the pressure exceeds the set safety value, the high-pressure protection mechanism is triggered, shutting down the compressor or reducing the system pressure to maintain normal operation.
Fault Analysis
The actual flow of the circulating water pump is too low; there may be blockages in the valves or filters in the water circuit; the valve is not fully open; the water temperature is set too high; the heat exchanger is scaled and blocked; there is air in the water system; there is a lack of water in the system.
Confirm through the pressure gauge that the system's high pressure has not reached the alarm pressure, then check whether the wiring of the pressure switch is reliable. Re-insert the wiring connections to ensure reliability. After shutdown, use a multimeter to check whether the high-pressure switch is conducting. If it is not conducting, the pressure switch may be faulty. Additionally, a blockage in the refrigerant system may also cause this situation.
Low-Pressure Protection
Low-pressure protection is a measure taken to prevent the compressor from operating under low-pressure conditions. When the system pressure is too low, the low-pressure protection device will be triggered, shutting down the compressor or reducing the compressor's operating load to prevent damage to the compressor caused by excessively low system pressure.
Fault Analysis
Check whether the unit has poor defrosting, or if the unit's fins are severely frosted; when the unit is off, measure whether the low-pressure is too low; if it is below 0.5 MPa, focus on checking whether there are any leaks or blockages in the refrigerant circuit; if it is above 0.5 MPa, focus on checking the low-pressure protection switch and the expansion valve. After shutdown, use a multimeter to test whether the low-pressure switch is conducting. If it is not conducting, the pressure switch may be faulty.
