Changing the direction of rotation of a single-phase motor. Changing the rotation of a single-phase electric motor. How to change the rotation of an asynchronous electric motor

Most often, our houses, plots, and garages are supplied with a single-phase 220 V network. Therefore, equipment and all home-made products are made so that they work from this power source. In this article we will look at how to correctly connect a single-phase motor.

Asynchronous or collector: how to distinguish

In general, you can distinguish the type of engine by the plate - the nameplate - on which its data and type are written. But this is only if it has not been repaired. After all, anything can be under the casing. So if you are not sure, it is better to determine the type yourself.

How do collector motors work?

You can distinguish between asynchronous and commutator motors by their structure. The collectors must have brushes. They are located near the collector. Another mandatory attribute of this type of engine is the presence of a copper drum, divided into sections.

Such motors are produced only as single-phase ones; they are often installed in household appliances, as they allow one to obtain a large number of revolutions at the start and after acceleration. They are also convenient because they easily allow you to change the direction of rotation - you just need to change the polarity. It is also easy to organize a change in the rotation speed by changing the amplitude of the supply voltage or its cutoff angle. That is why such engines are used in most household and construction equipment.

Disadvantages of commutator engines are high operating noise at high speeds. Think of a drill, an angle grinder, a vacuum cleaner, a washing machine, etc. The noise during their operation is decent. At low speeds, commutator motors are not so noisy (washing machine), but not all tools operate in this mode.

The second unpleasant point is that the presence of brushes and constant friction leads to the need for regular maintenance. If the current collector is not cleaned, contamination with graphite (from brushes being worn out) can cause adjacent sections in the drum to become connected and the motor simply stops working.

Asynchronous

An asynchronous motor has a starter and a rotor, and can be single or three phase. In this article we consider connecting single-phase motors, so we will only talk about them.

Asynchronous motors are characterized by a low noise level during operation, therefore they are installed in equipment whose operating noise is critical. These are air conditioners, split systems, refrigerators.

There are two types of single-phase asynchronous motors - bifilar (with a starting winding) and capacitor. The whole difference is that in bifilar single-phase motors the starting winding works only until the motor accelerates. Afterwards it is turned off by a special device - a centrifugal switch or a start-up relay (in refrigerators). This is necessary, since after overclocking it only reduces efficiency.

In capacitor single-phase motors, the capacitor winding runs all the time. Two windings - main and auxiliary - are shifted relative to each other by 90°. Thanks to this, you can change the direction of rotation. The capacitor on such engines is usually attached to the housing and is easy to identify by this feature.

You can more accurately determine the bifolar or capacitor motor in front of you by measuring the windings. If the resistance of the auxiliary winding is less than half (the difference can be even more significant), most likely this is a bifolar motor and this auxiliary winding is a starting winding, which means that a switch or starting relay must be present in the circuit. In capacitor motors, both windings are constantly in operation and connecting a single-phase motor is possible through a regular button, toggle switch, or automatic machine.

Connection diagrams for single-phase asynchronous motors

With starting winding

To connect a motor with a starting winding, you will need a button in which one of the contacts opens after switching on. These opening contacts will need to be connected to the starting winding. In stores there is such a button - this is PNDS. Its middle contact closes for the holding time, and the two outer ones remain in a closed state.

Appearance of the PNVS button and the state of the contacts after the “start” button is released"

First, using measurements, we determine which winding is working and which is starting. Typically the output from the motor has three or four wires.

Consider the option with three wires. In this case, the two windings are already combined, that is, one of the wires is common. We take a tester and measure the resistance between all three pairs. The working one has the lowest resistance, the average value is the starting winding, and the highest is the common output (the resistance of two windings connected in series is measured).

If there are four pins, they ring in pairs. Find two pairs. The one with less resistance is the working one, the one with more resistance is the starting one. After this, we connect one wire from the starting and working windings, and bring out the common wire. A total of three wires remain (as in the first option):

• one from the working winding is working;
• from the starting winding;
• general.

With all these

connecting a single-phase motor

We connect all three wires to the button. It also has three contacts. Be sure to place the starting wire on the middle contact(which is closed only during start-up), the other two are extremelyie (arbitrarily). We connect a power cable (from 220 V) to the extreme input contacts of the PNVS, connect the middle contact with a jumper to the working one ( pay attention! not with the general). That's the whole circuit for switching on a single-phase motor with a starting winding (bifolar) through a button.

Condenser

When connecting a single-phase capacitor motor, there are options: there are three connection diagrams and all with capacitors. Without them, the engine hums, but does not start (if you connect it according to the diagram described above).

The first circuit - with a capacitor in the power supply circuit of the starting winding - starts well, but during operation the power it produces is far from rated, but much lower. The connection circuit with a capacitor in the connection circuit of the working winding gives the opposite effect: not very good performance at start-up, but good performance. Accordingly, the first circuit is used in devices with heavy starting (for example), and with a working capacitor - if good performance characteristics are needed.

Circuit with two capacitors

There is a third option for connecting a single-phase motor (asynchronous) - install both capacitors. It turns out something between the options described above. This scheme is implemented most often. It is in the picture above in the middle or in the photo below in more detail. When organizing this circuit, you also need a PNVS type button, which will connect the capacitor only during the start time, until the motor “accelerates”. Then two windings will remain connected, with the auxiliary winding through a capacitor.

Connecting a single-phase motor: circuit with two capacitors - working and starting

When implementing other circuits - with one capacitor - you will need a regular button, machine or toggle switch. Everything connects there simply.

Selection of capacitors

There is a rather complex formula by which you can calculate the required capacity accurately, but it is quite possible to get by with recommendations that are derived from many experiments:

• The working capacitor is taken at the rate of 70-80 uF per 1 kW of engine power;
• starting - 2-3 times more.

The operating voltage of these capacitors should be 1.5 times higher than the network voltage, that is, for a 220 V network we take capacitors with an operating voltage of 330 V and higher. To make starting easier, look for a special capacitor in the starting circuit. They have the words Start or Starting in their markings, but you can also use regular ones.

Changing the direction of motor movement

If, after connecting, the motor works, but the shaft does not rotate in the direction you want, you can change this direction. This is done by changing the windings of the auxiliary winding. When assembling the circuit, one of the wires was fed to the button, the second was connected to the wire from the working winding and the common one was brought out. This is where you need to switch the conductors.

The direction of movement of the rotating magnetic field of asynchronous electric motors depends on the order of the phases, regardless of whether its stator windings are connected by a star or a triangle. For example, if phases A, B, C are applied to input terminals 1, 2 and 3, respectively, then the rotation will go (supposedly) clockwise, and if to terminals 2, 1, and 3, then counterclockwise. The connection diagram via a magnetic starter will save you from the need to unscrew the nuts in the terminal box and physically rearrange the wires.

Three-phase asynchronous machines at 380 volts are usually connected with a magnetic starter, in which three contacts are located on the same frame and close simultaneously, subject to the action of the so-called retractor coil - a magnetic solenoid operating on both 380 and 220 volts. This saves the operator from close contact with live parts, which can be unsafe at currents above 20 amperes.

For reverse starting, a pair of starters is used. The supply voltage terminals at the input are connected in a direct manner: 1–1, 2–2, 3–3. And at the exit counter: 4–5, 5–4, 6–6. To avoid a short circuit when accidentally pressing two “Start” buttons on the control panel simultaneously, voltage is supplied to the retractor coils through additional contacts of opposite starters. So that when the main group of contacts is closed, the line that goes to the solenoid of the adjacent device is open.

The control panel is equipped with a three-button post with single-position – one action per press – buttons: one “Stop” and two “Start”. The wiring in it is as follows:

• one phase wire is fed to the “Stop” button (it is always normally closed) and jumpers from it to the “Start” buttons, which are always normally open.
• From the “Stop” button there are two wires to additional contacts of the starters, which close when they are triggered. This ensures blocking.
• From the “Start” buttons, cross one wire to the additional contacts of the starters, which open when they are triggered.

Read more about connection diagrams for magnetic starters for three-phase electric motors.

Reversing single-phase synchronous machines

To start, these motors require a second winding on the stator, which includes a phase-shifting element, usually a paper capacitor. It is possible to reverse only those in which both stator windings are equivalent - in terms of wire diameter, number of turns, and also provided that one of them does not turn off after a set of revolutions.

The essence of the reversing circuit is that the phase-shifting capacitor will be connected to one of the windings, then to the other. For example, consider an asynchronous single-phase motor AIRE 80S2 with a power of 2.2 kW.

There are six threaded terminals in its terminal box, designated by the letters W2 and W1, U1 and U2, V1 and V2. To ensure that the motor rotates clockwise, the commutation is performed as follows:

• Mains voltage is supplied to terminals W2 and V1.
• The ends of one winding are connected to terminals U1 and U2. To power it, they are connected by jumpers according to the scheme U1–W2 and U2–V1.
• The ends of the second winding are connected to terminals W2 and V2.
• The phase shifting capacitor is connected to terminals V1 and V2.
• Terminal W1 remains free.

To rotate counterclockwise, change the position of the jumpers; they are placed according to the scheme W2–U2 and U1–W1. The automatic reverse circuit is also built on two magnetic starters and three buttons - two normally open “Start” and one normally closed “Stop”.

Reverse commutator motors

The connection circuit of its windings is similar to that used in DC motors with series excitation. One collector brush is connected to the stator winding, and the supply voltage is supplied to the other brush and the second terminal of the stator winding.

When the position of the plug in the socket changes, the rotor and stator magnets simultaneously reverse polarity. Therefore, the direction of rotation does not change. Just as this happens in a DC motor with a simultaneous change in the polarity of the supply voltage on the field and armature windings. It is necessary to change the order of phase - zero only in one element of the electrical machine - the collector, which provides not only spatial, but electrical separation of the conductors - the armature windings are isolated from each other. In practice this is done in two ways:

1. Physical change in the installation location of the brushes. This is irrational, since it is associated with the need to make changes to the design of the device. In addition, it leads to premature failure of the brushes, since the shape of the groove at their working end does not coincide with the shape of the commutator surface.
2. By changing the position of the jumper between the brush assembly and the excitation winding in the terminal box, as well as the connection point of the power cable. Can be implemented using one multi-position switch or two magnetic starters.

Do not forget that all work on rearranging jumpers in the terminal box or connecting the reversing circuit must be carried out with the voltage completely removed.

8. Operating principle and reverse (changing the direction of rotation) of a three-phase asynchronous motor.

The figure shows a cross-section of an electromagnetic circuit of an IM with a short-circuited rotor winding, including a stator (1), in the grooves of which there are three phase windings of the stator (2), represented by one turn. The beginnings of the phase windings are A, B, C, and the ends are X, Y, Z, respectively. In the cylindrical rotor (3) of the engine there are rods (4) of short-circuited windings, closed at the ends of the rotor by plates.

When three-phase voltage is applied to the phase windings of the stator, stator currents iA, iB, iC flow in the turns of the stator winding, creating a rotating magnetic field with a rotation frequency n1. This field crosses the short-circuited rotor winding rods and emfs are induced in them, the direction of which is determined by the right-hand rule. The EMF in the rotor bars is created by the rotor currents i2 and the magnetic field of the rotor, which rotates with the frequency of the stator magnetic field. The resulting magnetic field of the IM is equal to the sum of the magnetic fields of the stator and rotor. Conductors with current i2 located in the resulting magnetic field are subject to electromagnetic forces, the direction of which is determined by the left-hand rule. The total gain Fres applied to all rotor conductors forms the rotating electromagnetic torque M of the asynchronous motor.

The electromagnetic torque M, overcoming the moment of resistance Mc on the shaft, forces the rotor to rotate with a frequency n2. The rotor rotates with acceleration if the moment M is greater than the moment of resistance Mc, or with a constant frequency if the moments are equal.

The rotor rotation frequency n2 is always less than the rotation frequency of the machine's magnetic field n1, since only in this case does a rotating electromagnetic torque occur. If the rotor rotation frequency is equal to the rotation frequency of the stator MP, then the EM torque is zero (the rotor rods do not cross the motor MP, and the current is zero). The difference in the rotational speeds of the stator and rotor MP in relative units is called motor slip:

s = n 1− n 2. n 1

Slip is measured in relative units or percentages relative to n1. In an operating mode close to the nominal one, the engine slip is 0.01-0.06. Rotor speed n 2 = n 1 (1− s).

Thus, a characteristic feature of an asynchronous machine is the presence of slip - inequality of rotation frequencies of the magnetic field of the motor and rotor. That's why the machine is called asynchronous.

When an asynchronous machine operates in motor mode, the rotor speed is less than the motor speed and 0< s < 1. в этом режиме обмотка статора питается от сети, а вал ротора передает механический момент на исполнительный орган механизма. Электрическая энергия преобразуется в механическую.

If the IM rotor is inhibited (s = 1), this is a short circuit mode. If the rotor rotation frequency coincides with the rotation frequency of the motor, then engine torque does not occur. This is ideal idle mode.

To change the direction of rotation of the rotor (reverse the engine), you need to change the direction of rotation of the MP. To reverse the motor, you need to change the order of the phases of the supplied voltage, i.e. switch two phases.

9. Equivalent circuit and mechanical characteristics of a three-phase asynchronous motor.

In the circuit, an asynchronous machine with electromagnetic coupling of the stator and rotor circuits is replaced by an equivalent reduced equivalent circuit. In this case, the parameters of the rotor winding R2 and x2 are reduced to the stator winding under the condition of equality E1 = E2 ". E2 ", R2 ", x2 " are the given rotor parameters.

included in the winding of a stationary rotor, i.e. the machine has an active load.

The magnitude of this resistance is determined by the slip, and, consequently, the mechanical load on the motor shaft. If the moment of resistance on the motor shaft Mc = 0, then slip s = 0; in this case, the value R n =∞ and I2 " = 0, which corresponds to the work

engine in idle mode.

In no-load mode, the stator current is equal to the magnetizing current I 1 =I 0. The magnetic circuit of the machine is represented by a magnetizing circuit with parameters x0, R0 - inductive and active magnetization resistance of the stator winding. If the moment of resistance on the motor shaft exceeds its torque, the rotor stops. In this case, the value Rн = 0, which corresponds to the short circuit mode.

The first circuit is called a T-shaped replacement circuit for blood pressure. It can be converted into a simpler form. For this purpose, the magnetizing circuitZ 0 = R 0 + jx 0

carried out to common clamps. To ensure that the magnetizing current I 0 does not change its value, resistors R1 and x1 are connected in series to this circuit. In the resulting L-shaped equivalent circuit, the resistances of the stator and rotor circuits are connected in series. They form a working circuit, parallel to which a magnetizing circuit is connected.

The magnitude of the current in the operating circuit of the equivalent circuit:

mains voltage.

The electromagnetic torque of the IM is created by the interaction of the current in the rotor winding with the rotating MF of the machine. Electromagnetic torque M is determined through electromagnetic power:

Taking the number of motor phases m1 = 3 in the equation; x1 + x2 " = xк, we examine it for an extremum. To do this, we equate the derivative dM / ds to zero and get two extreme points. At these points, the moment Mk and the slip sk are called critical and are correspondingly equal:

The dependence of the EM torque on slip M(s) or on the rotor speed M(n2) is called the mechanical characteristic of the IM.

If we divide M by Mk, we obtain a convenient form of writing the equation for the mechanical characteristics of the blood pressure:

Hello, dear readers and visitors of the Electrician's Notes website.

In the last article we talked about it, got acquainted with the diagram of its connection to an electrical network with a voltage of 220 (V), the designation and marking of the terminals.

In the same article, I promised to tell you in the near future about how you can organize its reverse, i.e. control the direction of rotation of the motor remotely, and not using jumpers in the terminal box.

So let's get started.

In principle, there is nothing complicated. The principle of the control circuit is similar, with the exception of some details. Actually, I had never encountered a reverse circuit for single-phase motors before, and this was the first time I had put this circuit into practice.

The essence of the circuit comes down to changing the direction of rotation of the shaft of a single-phase capacitor motor remotely using buttons (button station). Remember, in the previous article we manually changed the position of two jumpers on the motor terminal block to change the direction of the operating winding (U1-U2). Now you need to remove these jumpers, because... their role in this circuit will be performed by normally open (NO) contacts of the contactors.

Preparing equipment for reversing a single-phase motor

First, let's list all the electrical equipment that we need to purchase to organize the reverse of the AIR 80S2 capacitor motor:

1. Circuit breaker

We use two-pole 16 (A), with characteristic “C” from IEK.

There are 3 buttons in this button post:

• forward button (black)
• back button (black)
• stop button (red)

Let's look at the push-button post.

We see that each button has 2 contacts:

• normally open contact (1-2), which closes when you press the button
• normally closed contact (3-4), which is closed until the button is pressed

Please note that in the photo the outermost button on the left is upside down. If you connect the reverse circuit of a single-phase motor yourself, then be careful, the buttons in the push-button post may be upside down. Refer to the contact markings (1-2) and (3-4).

3. Contactors

You also need to purchase two contactors. In my example, I use small-sized contactors KMI-11210 from IEK, which are installed on a DIN rail. These contactors have 4 normally open (NO) contacts and are capable of switching loads up to 3 (kW) at an alternating voltage of 230 (V). So they are just right for us, because... Our tested single-phase motor AIRE 80S2 has a power of 2.2 (kW).

Instead of contactors, you can purchase them, using the example of which I described their structure and principle of operation.

The coils of this contactor are designed for an alternating voltage of 220 (V), which will need to be taken into account when assembling the reverse control circuit for a single-phase motor.

Here, in fact, is my work.

I already said in the previous article that one of the readers of the site “Notes of an Electrician” named Vladimir asked me to help him with a power of 2.2 (kW) and draw up (come up with) a reverse circuit for him. Based on my sketches (including installation ones), Vladimir assembled the above diagram in . A little later he emailed me to say that he tested the circuit, everything works, no complaints.

If you have any questions about the site materials, then ask me in the comments or on . Within 12-24 hours, or maybe faster, it all depends on how busy I am, I will answer you.

Now I will tell you how this scheme works.

Operating principle of a single-phase motor reverse circuit

First of all, turn on the power supply.

1. Forward rotation

When you press the “forward” button, the coil of contactor K1 receives power through the following circuit: phase - NC. contact (3-4) of the “stop” button - n.c. contact (3-4) of the “back” button - n.o. contact (1-2) of the pressed “forward” button - contactor coil K1 (A1-A2) - zero.

Contactor K1 pulls up and closes all its normally open (NO) contacts:

• 1L1-2T1 (self-recovery of coil K1)
• 5L3-6T3 (simulates jumper U1-W2)
• 13NO-14NO (simulates jumper V1-U2)

There is no need to hold down the “forward” button, because... the contactor coil K1 is “self-retaining” through its own n.o. contact (1L1-2T1).

The single-phase motor begins to rotate in the forward direction.

2. Reverse rotation

When you press the “back” button, the coil of contactor K2 receives power through the following circuit: phase - NC. contact (3-4) of the “stop” button - n.c. contact (3-4) of the “forward” button - n.o. contact (1-2) of the pressed “back” button - contactor coil K2 (A1-A2) - zero.

Contactor K2 operates and closes its following normally open (NO) contacts:

• 1L1-2T1 (self-pickup coil K2)
• 3L2-4T2 (phase to motor in power circuit)
• 5L3-6T3 (simulates jumper W2-U2)
• 13NO-14NO (simulates jumper U1-V1)

There is no need to hold the back button with your finger, because... the contactor coil K2 is “self-retaining” through its own n.o. contact (1L1-2T1).

The single-phase motor begins to rotate in the opposite direction.

To stop the engine, you need to press the “stop” button.

3. Blocking

The presented reverse circuit of a capacitor single-phase motor has a button lock, i.e. If, when the engine is turned on in the forward direction, you mistakenly press the “back” button, then contactor K1 will first turn off, and then contactor K2 will work. And vice versa. Thus, we have a blocking from two simultaneously switched on contactors K1 and K2.

You can use other types of locks, but I limited myself to this one.

P.S. This concludes my article. If you liked my article, I will be very grateful if you share it on social networks. And also don’t forget to subscribe to my new articles - it will be more interesting later.

Quite often, the operating mode of auxiliary mechanized equipment requires a reduction in standard rotation speeds. This effect can be achieved by adjusting the speed of an asynchronous motor with your own hands. Let's try to figure out how to do this in practice (calculation and assembly), using standard control circuits or homemade devices.

• • Wound rotor motors

What is an asynchronous motor?

Asynchronous electric motors come in two main types: with a wound rotor and with a squirrel-cage rotor, the difference between which lies in the different designs of the rotor winding. This happens because we connect a 3-phase motor to a single-phase network. The primary winding contains 120 turns of wire with a diameter of 0.7 mm, with a tap from the middle, the secondary winding contains two separate windings of 60 turns of the same wire. The voltage value ultimately depends on the characteristics of the machine and the capacitance of the capacitors. It is known that the resistance of a cold filament of an incandescent lamp is 10 times less than the resistance of a hot filament.

If you turn on the IM in a 1-phase network, the torque will be created by only one winding.

In this case, the motor windings are connected in series. When the light comes on, it means that the 2 terminals belong to the same phase. Tags K1 and H3 (or H2) are placed on the terminals located in common knots (tied during the first part of the work) with H1 and K3, respectively. In order to create it, it is necessary to shift the phases on the windings using a special circuit.

Capacitors were used like KBG-MN or others with an operating voltage of at least 400 V. When the generator was turned off, an electric charge remained on the capacitors, so they were securely fenced to avoid electric shock.

To connect the motor according to a rather rare star circuit at startup, with subsequent transfer to a delta circuit for operation in operating mode. The engine begins to make a characteristic sound (hum). The motor is switched from one voltage to another by connecting the windings. You should not overload the engine and work “day and night”.

If the engine still hums after this, then this phase should also be set as before, and the next phase should be turned - II.

The disadvantages are: reduced and pulsating torque of a single-phase motor; increased heating; not all standard converters are ready for such work, because... Some manufacturers directly prohibit the use of their products in this mode.

If you use a dimmer in accordance with its purpose and comply with all conditions of use, you can achieve good results in controlling light sources indoors and outdoors.

Hello, dear readers and visitors of the Electrician's Notes website.

In the last article we talked about, got acquainted with the diagram of its connection to an electrical network with a voltage of 220 (V), the designation and marking of the terminals.

In the same article, I promised to tell you in the near future about how you can organize its reverse, i.e. control the direction of rotation of the motor remotely, and not using jumpers in the terminal box.

So let's get started.

In principle, there is nothing complicated. The principle of the control circuit is similar, with the exception of some details. Actually, I had never encountered a reverse circuit for single-phase motors before, and this was the first time I had put this circuit into practice.

The essence of the circuit comes down to changing the direction of rotation of the shaft of a single-phase capacitor motor remotely using buttons (button station). Remember, in the previous article we manually changed the position of two jumpers on the motor terminal block to change the direction of the operating winding (U1-U2). Now you need to remove these jumpers, because... their role in this circuit will be performed by normally open (NO) contacts of the contactors.

Preparing equipment for reversing a single-phase motor

First, let's list all the electrical equipment that we need to purchase to organize the reverse of the AIR 80S2 capacitor motor:

1. Circuit breaker

We use two-pole 16 (A), with characteristic “C” from IEK.

There are 3 buttons in this button post:

• forward button (black)
• back button (black)
• stop button (red)

Let's look at the push-button post.

We see that each button has 2 contacts:

• normally open contact (1-2), which closes when you press the button
• normally closed contact (3-4), which is closed until the button is pressed

Please note that in the photo the outermost button on the left is upside down. If you connect the reverse circuit of a single-phase motor yourself, then be careful, the buttons in the push-button post may be upside down. Refer to the contact markings (1-2) and (3-4).

3. Contactors

You also need to purchase two contactors. In my example, I use small-sized contactors KMI-11210 from IEK, which are installed on a DIN rail. These contactors have 4 normally open (NO) contacts and are capable of switching loads up to 3 (kW) at an alternating voltage of 230 (V). So they are just right for us, because... Our tested single-phase motor AIRE 80S2 has a power of 2.2 (kW).

Instead of contactors, you can purchase them, using the example of which I described their structure and principle of operation.

The coils of this contactor are designed for an alternating voltage of 220 (V), which will need to be taken into account when assembling the reverse control circuit for a single-phase motor.

Here, in fact, is my work.

I already said in the previous article that one of the readers of the site “Notes of an Electrician” named Vladimir asked me to help him with a power of 2.2 (kW) and draw up (come up with) a reverse circuit for him. Based on my sketches (including installation ones), Vladimir assembled the above diagram. A little later he emailed me to say that he tested the circuit, everything works, no complaints.

If you have any questions about the site materials, then ask me in the comments or on. Within 12-24 hours, or maybe faster, it all depends on how busy I am, I will answer you.

Now I will tell you how this scheme works.

Operating principle of a single-phase motor reverse circuit

First of all, turn on the power supply.

When you press the “forward” button, the coil of contactor K1 receives power through the following circuit: phase - NC. contact (3-4) of the “stop” button - n.c. contact (3-4) of the “back” button - n.o. contact (1-2) of the pressed “forward” button - contactor coil K1 (A1-A2) - zero.

Contactor K1 pulls up and closes all its normally open (NO) contacts:

• 1L1-2T1 (self-recovery of coil K1)
• 5L3-6T3 (simulates jumper U1-W2)
• 13NO-14NO (simulates jumper V1-U2)

There is no need to hold down the “forward” button, because... the contactor coil K1 is “self-retaining” through its own n.o. contact (1L1-2T1).

The single-phase motor begins to rotate in the forward direction.

2. Reverse rotation

When you press the “back” button, the coil of contactor K2 receives power through the following circuit: phase - NC. contact (3-4) of the “stop” button - n.c. contact (3-4) of the “forward” button - n.o. contact (1-2) of the pressed “back” button - contactor coil K2 (A1-A2) - zero.

Contactor K2 operates and closes its following normally open (NO) contacts:

• 1L1-2T1 (self-pickup coil K2)
• 3L2-4T2 (phase to motor in power circuit)
• 5L3-6T3 (simulates jumper W2-U2)
• 13NO-14NO (simulates jumper U1-V1)

There is no need to hold the back button with your finger, because... the contactor coil K2 is “self-retaining” through its own n.o. contact (1L1-2T1).

The single-phase motor begins to rotate in the opposite direction.

To stop the engine, you need to press the “stop” button.

3. Blocking

The presented reverse circuit of a capacitor single-phase motor has a button lock, i.e. If, when the engine is turned on in the forward direction, you mistakenly press the “back” button, then contactor K1 will first turn off, and then contactor K2 will work. And vice versa. Thus, we have a blocking from two simultaneously switched on contactors K1 and K2.

You can use other types of locks, but I limited myself to this one.

P.S. This concludes my article. If you liked my article, I will be very grateful if you share it on social networks. And also don’t forget to subscribe to my new articles - it will be more interesting later.