Features of the purpose of the start-up relay for the refrigerator compressor motor. Possible choices and expediency of independent replacement of the refrigerator part. When using a three-phase refrigerator motor, the installation of a starting winding is not necessary. When connected to a 380 V network, the device functions in such a way that all stator coils are phased independently. However, when using a 220 V network, it becomes necessary to use additional components (triangular and star circuits with the presence of a compressor).
This feature allows you to check and provide the required voltage in one of the windings, in relation to the others by 90 degrees. Thus, the first winding is the starting winding, and the compressor motor will turn off at maximum speed. The system used when connecting the refrigerator to the 220V line actually makes a two-phase analogue of a three-phase motor.
Features of starting an asynchronous motor when using a single-phase network. As you know, 380V is formed from three phases of 220V each, but in this case we are talking about the real value, but not about the amplitude (the parameter causing the thermal effect with passive resistance). Simply put, the AC voltage indicators are constantly changing, therefore, for convenience, they are averaged. This is considered an effective value.
Refrigerator relay features
For the full functioning of an asynchronous type motor installed in a refrigerator, the field inside must necessarily rotate. However, the necessary factor can be ensured and checked by applying the appropriate value to the three windings of the phase. The result of the action is the vector addition of the fields, which ensures rotation, which carries the rotor along with it. The indicators that are available when connecting a three-phase motor to a 380 V line are the highest of all types of connection. This becomes the reason for the widespread use of the process in industrial production, but it is not very suitable for household refrigerators.
In the presence of only one phase, the rotation of the field is in principle impossible, since at least two vectors are required for movement. The installation of a compressor that provides a voltage shift of 90 degrees helps to obtain the necessary indicators in the conditions of private apartments and houses. The alternating field obtained during rotation activates the rotor in the required direction. Of course, the process is not as smooth as in the presence of three vectors, but this is enough for the operation of household appliances.
The presence of three-phase voltage in private homes is not provided for connecting the refrigerator. But why? The reason lies in the need for special skills and knowledge of theory, which is quite difficult for the average layman to perceive. With one phase and one ground, the use of household appliances becomes simple and convenient, which allows you to miss out on performance for the sake of comfort.
What does the starting winding do? At the beginning of starting the engine, the relay provides the creation of a second vector, due to which the field generated in the process can be considered rotating. Not being an even circle, its indicators are enough to spin the rotor. At full speed, to save energy and increase efficiency, the starting coil of the refrigerator is turned off.
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The principle of operation of the start-up relay of the refrigerator
How does the starting coil turn off when the speed is reached? At the beginning of the relay operation, the maximum energy consumption is observed, on which everything is based. In addition, a start relay is often used for additional protection. The shutdown is carried out when the special element warms up. After reaching the maximum value, the circuit loses its integrity, regardless of whether the set mode of the refrigerator is reached. There are the following schemes for the functioning of the starting relay:
"Pills". They are made from a substance capable of expanding when heated. The part is cold when the refrigerator is turned on. However, with a gradual increase in temperature, the contact opens, due to which only the coil remains functional. Some experts believe that maintaining the desired mode can be achieved by using a working winding choke. You can check this empirically.
See also - Features of the refrigerator thermostat
Induction relays work on the principle of the interaction of electromagnets. During startup, the refrigerator systems consume the maximum amount of energy, which leads to the interaction of the core and the contacts of the starting coil. When the current falls further, the mechanism is weakened and the connections open.
It is important to note that, along with tablets, the body of the device is often also equipped with thermal relays mounted on bimetallic plates. This allows the contacts to be opened immediately after exceeding the trip threshold. The operation of a relay of this type is carried out by heating the sensitive element. Such a compressor protection scheme is considered one of the most common for household appliances.
Start-up relay design
The start-up, or start relay, used in some models of refrigerators, is shaped like a tablet. This element is located at the compressor motor housing (black part). Interestingly, manufacturers always choose black for this part. But why?
Black is capable of absorbing as well as radiating heat. The movement of the process depends on the temperature difference between the external environment and the compressor. In situations where the motor is heated, heat is generated. To speed up the cooling process, a fan is sometimes used to dissipate heat more quickly into the surrounding space.
The start-up element, as a rule, has:
- a 220 V phase and a ground phase (with two inputs);
- starting and working winding of an asynchronous motor, as well as the ground phase (with three inputs);
To facilitate the process of connecting the refrigerator for the consumer, the colors in which the wires are painted help. However, even under obvious conditions, it is recommended that the refrigerator and its components be repaired with caution. To determine the ground of the compressor, a small layer of paint can be removed from the case, which will make it possible to check all contacts. Despite the simplicity of this method, it is best left in case other options are out of the question.
Device location
The compressor relay of RTP-models has some differences, and can be located on the wire (without attachment to the frame). The working process, at the same time, is carried out with a DXM compressor, and differs from DXR in lower current indicators when triggered.Such a device makes it possible to qualitatively protect the compressor in the presence of such a sinking current.
Before purchasing a relay, it is important to check if it matches the compressor type. A good installation also matters. The best option when choosing a device is to purchase a product brand similar to the one installed earlier.
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