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  • Name: Why does the refrigeration compressor cause overheat protection?Precautions in use for Overload protector

First, why does the compressor cause overheat protection?
Overload protector working principle and classification Overload protector of air conditioner compressor is usually a snap-type bimetal protector. It is composed of heating wire, bimetal and two static contacts, connected in series in the compressor circuit. .
When the current in the circuit is too high, the heating wire heats and bake the dish-shaped bimetal. When the bimetal heats up, it will bend in the opposite direction, thus breaking the contact. When the temperature of the compressor housing or the motor is too high. When the operating current is normal, the heating wire generates little heat.
The bimetal will also deform and bend upwards, breaking away from the two static contacts and cutting off the circuit. This protector can automatically reset, with over-current, over-temperature rise double protection.
Why does the refrigeration compressor produce overheat protection? Overload protector in the use of attention to what matters?
Second, the overload protector works and classification
1, the overload protector works
a. The refrigeration compressor overload protector used in the general refrigeration system is a snap-type bimetal protector.
b. The protector is a complete circuit consisting of a heating wire, a bimetallic strip and two stationary contacts, which are then connected in series to the circuit where the refrigeration compressor is located.
c. Its working principle is that when the current inside the system circuit increases for no reason, the heating wire will generate a lot of heat. When the bimetal is baked under the heat of the heating wire, it will become reversely arched, so as to achieve the purpose of disconnecting from the electric shock and cutting off the entire circuit.
d. Even if the current in the circuit is small, the same phenomenon may occur if the temperature of the housing or motor of the refrigeration compressor is too high. In order to effectively protect the safe operation of refrigeration compressors. More convenient is that this protection can be automatically reset, so the use of the process is very convenient.
2, the classification of overload protector
Under normal circumstances, overload protectors are classified according to the different installation methods, and are mainly divided into two types: external and built-in overload protectors:
a. Introduction of external overload protection device
The external overload protection device is generally installed on the sealing terminal of the refrigerating compressor shell, and should be kept close to the upper cover, so as to ensure that the temperature abnormality on the refrigeration compressor shell is sensitively sensed;
Because there is a conduction and convection process from the heat generated by the motor to the housing of the refrigeration compressor, there is another process that is sensed from the heat of the housing to the overload protector, so the accuracy and reliability of this method are not particularly good. Therefore, the reasons for the extensive use of external overload protectors are more because of their relatively simple manufacture and relatively low cost.
At the same time, the external overload protector has obvious advantages such as easy installation and maintenance, so it is used more in some low-power electrical aspects;
b. Introduction of built-in overload protector
The built-in overload protector is subdivided into two types: banding type and plug-in type: The band-type overload protector is bound by the motor coils as the name suggests, and thus serves the purpose of directly sensing the temperature change of the coil. The advantage is that the reaction is very sensitive and accurate;
The plug-in type overload protection device is that the protection device is directly plugged into the sealing terminal. The main principle is to sense whether the temperature of the motor is normal through the heat conduction of the refrigerant. This kind of protector has certain limitations, that is, it is very sensitive in the case of no leakage of refrigerant, but if there is a case of refrigerant leakage, such a protector is also useless.
Therefore, in general, external overload protection devices are not as effective as the built-in ones in terms of their sensitivity, accuracy, and reliability. However, their cost is relatively low, so there is also a certain market space. However, the scope of adaptation is still much smaller than that of the built-in one. However, the cost of the built-in overload protector is several times higher than that of the external type. Therefore, all friends can make appropriate choices according to their own conditions of use and requirements.
Third, the overload protector in the use of the process of attention
a. Overload protector of refrigerating compressor According to the different configuration methods, the protection function of the refrigerating compressor is completely different. Overall, the built-in overload protector has higher sensitivity and accuracy than the external overload protection. , so it also has a much greater protective effect on refrigeration compressors;
b. In the case of insufficient refrigerant or leakage, the protection effects of the two types of overload protectors are very limited. Therefore, in order to prevent ineffective protection, a complete protection system is generally required to provide special protection against insufficient refrigerant.
c, in the case of too much refrigerant, the protection of the two overload protectors is also limited, so there must be a corresponding supplementary measures to ensure that the refrigeration compressor is not harmed;
d. In the case of high compression ratio, the protection function of the overload protector is also very weak, so it is also necessary to separately set low-voltage protection measures to protect the refrigeration compressor.


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