Refrigerator compressor start relay: diagram and principle of operation

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.

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The principle of operation of the refrigerator start-up relay

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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.

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

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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.

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 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.

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