High pressure protection is to detect whether the refrigerant pressure in the system is normal. When the pressure exceeds the allowable range, the pressure switch will activate and transmit an abnormal signal to the high pressure controller. After processing, the refrigeration system will stop working and display the fault.
1. High voltage protection
High pressure protection is to detect whether the refrigerant pressure in the system is normal. When the pressure exceeds the allowable range, the pressure switch will activate and transmit an abnormal signal to the high pressure controller. After processing, the refrigeration system will stop working and display the fault.
2. Low voltage protection
Low pressure protection detects the return air pressure in the system, which prevents damage to the compressor due to low system pressure or lack of refrigerant operation. If the system leaks and there is no refrigerant, forced operation will damage the compressor. At this time, low-pressure protection can respond promptly, control the system to stop and display faults, and protect the compressor and refrigeration system.
3. Oil pressure protection
A device that prevents bearings or other internal components of the compressor from being damaged due to low lubricating oil pressure. If the oil volume of the compressor decreases or the oil is cut off, it will cause serious damage to the high-speed compressor. The oil pressure protection device is an important component to ensure the safe operation of the compressor.
4. Antifreeze protection
If the evaporator is too dirty or frosting is too severe, the cold air cannot fully exchange heat with the outside hot air, causing the internal unit to freeze. Indoor antifreeze protection is designed to stop the compressor before the internal unit freezes, providing protection for the compressor.
5. Overheating protection
A well-designed motor that operates under specified conditions will not have an internal temperature exceeding the allowable value. However, when the motor operates at high or low voltage, or in a high-temperature environment, the internal temperature of the motor will exceed the allowable value. During frequent starting, the temperature may become too high due to excessive starting current.
6. High temperature protection
Excessive exhaust temperature can cause refrigerant decomposition, aging of insulation materials, carbonization of lubricating oil, damage to air valves, and blockage of capillary tubes and dry filters. The main protection method is to use a temperature controller to sense the exhaust temperature. The temperature controller should be placed near the exhaust port. When the exhaust temperature is too high, the temperature controller will activate and cut off the circuit.
7. Oil temperature protection
To prevent the lubricating oil temperature from being too high, during the operation of the compressor, sometimes even if the oil pressure difference is normal, the lubrication performance may decrease due to the high oil temperature, causing friction components such as bearings to be burned out. Therefore, it is necessary to control the oil temperature protection.
8. Cooling water cut-off protection
If the cooling water of the compressor water jacket is cut off, it will cause an increase in the exhaust temperature of the compressor, and in severe cases, it may cause deformation of the cylinder. Install a pair of electrical contacts on the outlet pipeline of the compressor cooling water jacket. When there is water flow, the electrical contacts are connected by the water, and the relay sends a signal to put the compressor in a starting or normal operation state. If the water flow is interrupted, the electrical contact of the relay will disconnect, and the compressor cannot start or shut down in case of an accident. But there are often bubbles in the water flow, which can cause misoperation, and the water jacket breaking water will not immediately cause an accident, so the relay should be delayed in action, usually for 15-30s.
9. Chassis temperature protection
The temperature of the casing will affect the lifespan of the compressor. The high temperature of the casing may be caused by insufficient heat transfer capacity of the condenser, so it is necessary to check whether the air or water volume of the condenser and the water temperature are appropriate. If air or other non condensable gases are mixed into the refrigeration system, the condensation pressure will rise and the casing will overheat; If the suction temperature is too high, the casing is prone to overheating. In addition, overheating of the motor can also cause overheating of the casing.
10. Current protection
When a short circuit occurs in a power line, one of the important characteristics is that the current in the line increases sharply. This requires the setting of a corresponding protection device called overcurrent protection, which responds to the increase in current when the current flows through a predetermined value.
11. Overheating protection
A well-designed motor that operates under specified conditions will not have an internal temperature exceeding the allowable value. However, when the motor operates at high or low voltage, or in a high-temperature environment, the internal temperature of the motor will exceed the allowable value. During frequent starting, the temperature may become too high due to excessive starting current.
12. Delay start protection
During the operation of the air conditioner, the compressor may stop running due to various reasons. At this time, the high and low pressures in the system will not immediately balance. If the compressor is started at this time, the starting current may be too high due to pressure problems, which may burn out the air conditioner. Therefore, current air conditioners are equipped with delayed start protection, which means that after each compressor stops running, there is a delay of 3-5 minutes before it can be restarted.
13. Phase sequence protection
Phase sequence protection is a protective relay that can automatically identify the phase sequence, avoiding accidents or equipment damage caused by reversing the power supply phase sequence (three live wires connected in reverse) to the motor. For example, the structures of scroll compressors and piston compressors are different. Due to the fact that the inverter of the three-phase power supply can cause the compressor to invert, it cannot be reversed. Therefore, it is necessary to install a reverse phase protector to prevent the reverse rotation of the chiller unit. When installing a reverse phase protector, the compressor can operate in the positive phase. When opposite phases occur, it is necessary to change the two lines of the power supply to positive phase.
14. Phase imbalance protection
Unbalanced voltage between phases will cause three-phase unbalanced current, resulting in greater temperature rise - set overload relay. In the maximum phase of the current
15. Voltage protection
Shutdown is more common in air conditioning systems, which are equipped with overvoltage and undervoltage protection boards and can also achieve phase loss protection. After protection, corresponding light-emitting diodes light up.
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