Features of the purpose of the start-up relay of the refrigerator compressor motor. Possible choices and the feasibility of self-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 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 the asynchronous type motor installed in the refrigerator, the field that is inside must necessarily rotate. However, it is possible to provide and verify the necessary factor by applying the corresponding value to the three phase windings. The result of the action is the vector addition of fields, in which rotation is provided, which carries away the rotor. 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 is not suitable for domestic refrigerators.
If there is only one phase, the rotation of the field is in principle impossible, since at least two vectors are required for motion. The installation of a compressor that provides a voltage shift of 90 degrees helps to obtain the necessary indicators in 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 person 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 engine start-up, the relay provides the creation of a second vector, due to which the field formed in the process can be considered rotating. Not being an even circle, its indicators are enough to spin up 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 picked up? At the beginning of the relay, the maximum energy consumption is observed, on which everything is based. In addition, a start relay is often used for additional protection. Shutdown is carried out when a special element is heated. 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 operation schemes of the start relay:
"Pills". They are made from a substance capable of expanding when heated. When you turn on the refrigerator, the part is cold. 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 through the use of a choke of the working winding. You can verify this empirically.
See also - Features of the refrigerator thermostat
Induction relays work on the principle of the interaction of electromagnets. During start-up, 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 circuit 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 able to absorb as well as radiate heat. The movement of the process depends on the temperature difference between the external environment and the compressor. In situations where the motor heats up, 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);
The colors in which the wires are painted help to facilitate the process of connecting the refrigerator for the consumer. However, even under obvious conditions, it is recommended that the refrigerator and its components be repaired carefully.To determine the compressor ground, you can remove a small layer of paint from the housing, which will make it possible to check all the contacts. Despite the simplicity of this method, it is better to leave it in case other options are excluded.
Device location
The compressor relay of the RTP models has some differences, and can be located on the wire (without mounting to the frame). The workflow, in this case, 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 lowering current.
Before buying a relay, it is important to check its compliance with the type of compressor. Quality installation also matters. The best option when choosing a device is to purchase a product brand similar to that previously installed.
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