Features of the purpose of the start-up relay 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 (triangle and star circuits with the presence of a compressor).
This feature allows you to check and provide the necessary voltage in one of the windings, in relation to the others by 90 degrees. Thus, the first winding is starting, and the compressor motor will turn off at maximum speed. The system used when connecting the refrigerator to the 220V line actually turns a three-phase motor into a two-phase analogue.
Features of starting an asynchronous type motor when using a single-phase network. As you know, 380V is formed from three phases of 220V, but in this case we are talking about the real value, but not about the amplitude (a parameter that causes a thermal effect with passive resistance). Simply put, AC voltage indicators are constantly changing, therefore, for convenience, they are averaged. This is considered the effective value.
Refrigerator Relay Features
For the full functioning of an asynchronous type motor installed in a refrigerator, the field that is inside must necessarily rotate. However, it is possible to provide and check the necessary factor 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, dragging 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 is the reason for the widespread use of the process in industrial production, but is not suitable for domestic 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 generated during rotation activates the rotor in the required direction. Of course, the process is not as smooth as with three vectors, but this is enough for household appliances to work.
The presence of three-phase voltage in private dwellings for connecting a refrigerator is not provided. But why? The reason is the need for special skills and knowledge of theory, which is quite difficult for the perception of the average layman. With one phase and one ground, the use of household appliances becomes simple and convenient, which allows you to lose performance for the sake of comfort.
What does the starting winding do? At the beginning of the engine start, 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.
The principle of operation of the refrigerator start-up relay
How does the starter coil turn off at revs? At the beginning of the relay operation, the maximum energy consumption is observed, on which everything is based. In addition, often a starting relay is used for additional protection. Switching off is carried out when a special element is heated. After reaching the maximum value, the circuit loses integrity, regardless of whether the set refrigerator mode is reached. There are the following schemes for the operation of the starting relay:
“Tablets”. They are made from a substance capable of expanding when heated. When the refrigerator is switched on, the part is cold. However, with a gradual increase in temperature, the contact opens, due to which only the coil remains functioning. Some experts believe that maintaining the desired mode can be done through the use of a working winding inductor. This can be verified experimentally.
See also - Features of the refrigerator thermostat
Induction relays work on the principle of interaction of electromagnets. During start-up, refrigerator systems consume the maximum amount of energy, which leads to the interaction of the core and the contacts of the starting coil. With a drop in current, which follows further, the mechanism is weakened and the connections open.
It is important to note that, along with tablets, often the body of the device is also equipped with thermal relays mounted on bimetallic plates. This allows you to open the contacts immediately after exceeding the threshold. The operation of this type of relay is carried out by heating the sensing element. This compressor protection scheme is considered one of the most common for household appliances.
The design of the starting relay
The start-up, or start-up 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 color is able to absorb as well as radiate heat. The movement of the process depends on the temperature difference between the 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, due to which the heat quickly escapes into the surrounding space.
The start-protective element, as a rule, has:
- 220 V phase and ground phase (with two inputs);
- starting and working winding of an asynchronous motor, as well as the earth 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, repairs to the refrigerator and its components are recommended to be done carefully. To determine the ground of the compressor, you can remove a small layer of paint from the case, 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.
The compressor relay of the RTP models has some differences, and can be located on the wire (without mounting 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 lowering current.
Before buying a relay, it is important to check its compatibility with the type of compressor. A quality installation also matters. The best option when choosing a device is to purchase a brand of a product similar to the one installed earlier.