A single-phase motor operates using AC electric current and connects to single-phase networks. The network must have a voltage of 220 Volts and a frequency of 50 Hertz.
Electric motors of this type are used mainly in low-power devices:
- Household appliances.
- Fans low power.
- Pumps.
- Machine tools for processing raw materials, etc.
Models are available with power from 5 W to 10 kW.
The values of efficiency, power and starting torque for single-phase motors are significantly lower than for three-phase devices of the same size. The overload capacity is also higher for 3-phase motors. Thus, the power of a single-phase mechanism does not exceed 70% of the power of a three-phase mechanism of the same size.
device Device:
- Actually has 2 phases, but only one of them does the work, so the motor is called single-phase.
- Like all electric machines, a single-phase motor consists of 2 parts: stationary (stator) and moving (rotor).
- Represents, on the stationary component of which there is one working winding connected to a single-phase source alternating current.
TO strengths engine of this type This can be attributed to the simplicity of the design, which is a rotor with a short-circuited winding. The disadvantages are low starting torque and efficiency.
The main disadvantage of single-phase current– the impossibility of generating a magnetic field that performs rotation. Therefore, a single-phase electric motor will not start on its own when connected to the network.
In theory electric machines, the rule applies: In order for a magnetic field to arise that rotates the rotor, there must be at least 2 windings (phases) on the stator. It is also required to shift one winding by a certain angle relative to the other.
During operation, alternating electric fields flow around the windings:
- According to this, on the stationary section of a single-phase motor there is a so-called starting winding. It is shifted 90 degrees relative to the working winding.
- Current shift can be obtained by including a phase-shifting link in the chain. Active resistors, inductors and capacitors can be used for this.
- As a basis 2212 electrical steel is used for the stator and rotor.
It is incorrect to call single-phase electric motors that are 2- and 3-phase in structure, but are connected to a single-phase power source through matching circuits (capacitor electric motors). Both phases of such devices are working and are turned on all the time.
Operating principle and startup scheme
Principle of operation:
- Electric shock a pulsating magnetic field is generated on the motor stator. This field can be considered as 2 different fields that rotate in different directions and have equal amplitudes and frequencies.
- When the rotor is stationary, these fields lead to the appearance of moments equal in magnitude, but differently directed.
- If the engine does not have special starting mechanisms, then at start the resulting torque will be zero, which means the engine will not rotate.
- If the rotor is rotated in one direction, then the corresponding torque begins to prevail, which means that the motor shaft will continue to rotate in the given direction.
Launch scheme:
- The launch is carried out by a magnetic field, which rotates the moving part of the motor. It is created by 2 windings: main and additional. The latter is smaller in size and is a launcher. It connects to the main electrical network through capacitance or inductance. The connection is made only during start-up. In low power motors, the starting phase is short-circuited.
- Starting the engine carried out by holding the start button for several seconds, as a result of which the rotor accelerates.
- When releasing the start button, the electric motor switches from two-phase mode to single-phase mode, and its operation is supported by the corresponding component of the alternating magnetic field.
- Start phase designed for short-term operation – usually up to 3 s. More long time being under load can lead to overheating, insulation fire and mechanism failure. Therefore, it is important to release the start button in a timely manner.
- In order to improve reliability A centrifugal switch and a thermal relay are built into the housing of single-phase motors.
- Centrifugal switch function consists of switching off the starting phase when the rotor reaches its rated speed. This happens automatically - without user intervention.
- Thermal relay turns off both phases of the winding if they heat up above the permissible level.
Connection
To operate the device, 1 phase with a voltage of 220 Volts is required. This means that you can plug it into a household outlet. This is precisely the reason for the popularity of the engine among the population. For everyone household appliances, from juicer to grinding machine, mechanisms of this type are installed.
connection with starting and running capacitors 
There are 2 types of electric motors: with a starting winding and with a running capacitor:
- In the first type of devices, the starting winding works through a capacitor only during start. Once the machine reaches normal speed, it turns off and operation continues with one winding.
- In the second case, for motors with a working capacitor, the additional winding is permanently connected through the capacitor.
An electric motor can be taken from one device and connected to another. For example, a working single-phase motor from a washing machine or vacuum cleaner can be used to operate a lawn mower, processing machine, etc.
There are 3 schemes for switching on a single-phase motor:
- In 1 scheme, the work of the starting winding is carried out by means of a capacitor and only for the start-up period.
- 2 scheme also provides for short-term connection, but it occurs through a resistance and not through a capacitor.
- 3 scheme is the most common. In this scheme, the capacitor is constantly connected to a source of electricity, and not just during startup.
Connecting an electric motor with starting resistance:
- Auxiliary winding Such devices have increased active resistance.
- To start an electric machine of this type, a starting resistor can be used. It should be connected in series to the starting winding. Thus, it is possible to obtain a phase shift of 30° between the winding currents, which will be quite enough to start the mechanism.
- Besides, the phase shift can be obtained by using a starting phase with a larger resistance value and a smaller inductance value. This winding has fewer turns and thinner wire.
Connecting a motor with capacitor start:
- For these electric machines the starting circuit contains a capacitor and is turned on only for the start period.
- To achieve the maximum value starting torque, a circular magnetic field is required to perform the rotation. For it to occur, the winding currents must be rotated 90° relative to each other. Phase-shifting elements such as a resistor and inductor do not provide the necessary phase shift. Only the inclusion of a capacitor in the circuit allows you to obtain a phase shift of 90°, if you select the capacitance correctly.
- Calculate Which wires belong to which winding can be determined by measuring the resistance. For the working winding, its value is always less (about 12 Ohms) than for the starting winding (usually about 30 Ohms). Accordingly, the cross-section of the working winding wire is larger than that of the starting winding.
- Capacitor selected according to the current consumed by the motor. For example, if the current is 1.4 A, then a capacitor with a capacity of 6 μF is required.
Functionality check
How to check engine performance by visual inspection?
The following are defects that indicate possible problems with the engine, they could be caused by improper operation or overload:
- Broken prop or mounting slots.
- In the middle of the motor the paint has darkened (indicates overheating).
- Through the cracks foreign substances are drawn into the device inside the housing.
To check the performance of the engine, you should first turn it on for 1 minute, and then let it run for about 15 minutes.
If after this the engine is hot, then:
- Maybe, the bearings are dirty, jammed or simply worn out.
- Cause The capacitor may be too high.
Disconnect the capacitor and start the motor manually: if it stops heating, you need to reduce the capacitor capacitance.
Model overview
electric motor AIR One of the most popular are electric motors of the AIR series. There are models made on feet 1081, and models of combined design - feet + flange 2081.
Electric motors in the foot + flange design will cost about 5% more than similar ones with feet.
As a rule, manufacturers provide a warranty of 12 months.
For electric motors with a rotation height of 56-80 mm, the frame is made of aluminum. Motors with a rotation height of more than 90 mm are available in cast iron.
Models differ in power, rotation speed, height of the rotation axis, and efficiency.
The more powerful the engine, the higher its cost:
- Motor with power 0.18 kW can be purchased for 3 thousand rubles (electric motor AIRE 56 B2).
- 3 kW model will cost about 10 thousand rubles (AIRE 90 LB2).
As for the rotation speed, the most common models are with frequencies of 1500 and 3000 rpm, although there are engines with other frequency values. With equal power, the cost of an engine with a speed of 1500 rpm is slightly higher than that of one with a speed of 3000 rpm.
The height of the rotation axis for motors with 1 phase varies from 56 mm to 90 mm and directly depends on the power: the more powerful the engine, the greater the height of the rotation axis, and therefore the price.
Different models have different efficiencies, typically ranging from 67% to 75%. Greater efficiency corresponds to a higher cost of the model.
You should also pay attention to engines produced by the Italian company AACO, founded in 1982:
- Thus, the AACO electric motor series 53, designed specifically for use in gas burners. These motors can also be used in washing machines, generators warm air, central heating systems.
- Electric motors series 60, 63, 71 designed for use in water supply installations. Also, the company offers universal motors of the 110 and 110 compact series, which are distinguished by a diverse range of applications: burners, fans, pumps, lifting devices and other equipment.
You can buy motors produced by AACO for a price starting from 4,600 rubles.
Capacitor single-phase motors series AIRE and ADME are intended for completing household and industrial electric drives - various mechanisms that do not require rotation speed adjustment (woodworking machines, pumps, compressors, concrete mixers, etc.).
Main (basic) version– asynchronous single-phase capacitor electric motor with two working windings and a small-sized attached working capacitor, designed for operating mode S1, powered by an alternating current network of 50 Hz with a voltage of 220V, climatic version and placement category U3; degree of protection IP54, with typical technical characteristics, meeting the requirements of the standards. Motors with the designation AIRE...K2 have an additional starting capacitor and are characterized by an increased starting torque.
Single-phase electric motors with two windings (AIRE, AIRE...K2, ADME series)
Power |
ED type |
efficiency, |
Inom, |
Mnom, |
N nom, |
Mn/Mn |
Mmax/Mn |
Srab, |
Descent, |
Uns, |
Weight IM1081, |
||
Synchronous speed 3000 rpm |
|||||||||||||
Synchronous speed 1500 rpm |
|||||||||||||
**motor weight is indicated for version IM3081
Crab, Descent – the capacity of the working and starting capacitors, respectively
Uns – voltage of the working/starting capacitor, respectively
Single-phase capacitor motors are called single-phase because they are connected to a single-phase alternating current network. But they can also be called two-phase, since their stator contains two windings - working and starting.
The starting winding serves to create the initial torque of the electric motor, since an electric motor with one winding has zero torque. The starting winding of a conventional single-phase electric motor has the same number of slots and the same power as the working winding. It is laid in the stator at an angle of 90° (see Figure 2) to the working winding and connected to the network through a phase-shifting element - the working capacitor. The capacitor and the starting winding are usually constantly turned on - both at the time of start-up and during operation of a single-phase electric motor. The winding diagram of a conventional single-phase electric motor is shown in Figure 1a.
Rice. 1 Schemes of capacitor single-phase electric motors: a) single-capacitor; b) two-capacitor
Rice. 2. Laying windings in the stator of a single-phase electric motor
Single-phase motor speed at Idling less than that of a three-phase motor with the same synchronous magnetic field speed due to the presence of braking torque. For the same reason, a single-phase motor has worse performance characteristics: lower starting torque, lower efficiency, lower overload capacity, increased slip at rated load.
In order for a single-phase electric motor to have characteristics as close as possible to a three-phase electric motor, it is necessary to create a rotating magnetic field in its stator as close to circular as possible. This is achieved correct selection capacity of the working capacitor depending on the current in the winding. But since the starting and operating currents differ significantly, one working capacitor is not able to provide an ideal magnetic field in all operating modes of a single-phase electric motor. In conventional single-phase electric motors, the capacitor is selected for the rated current. Accordingly, its capacity is not enough at start-up and such a single-phase electric motor has a reduced starting torque.
In the case when starting conditions require a higher starting torque from a single-phase motor, it is desirable to have additional starting capacity. To do this, single-phase motors are switched on through an additional control unit, which contains a starting capacitor Sp and makes it possible to automatically connect this capacitor during start-up, as well as during overloads. The starting capacitor allows for the best output characteristics of a single-phase motor. The connection diagram for a single-phase electric motor with an additional starting capacitor is shown in Figure 1b.
The diagram for connecting the windings and the working capacitor to the connectors of the terminal box, as well as the diagram for connecting a single-phase electric motor to the network for “forward” and “reverse” directions of rotation are shown in Figure 3.
Rice. 3 Connection diagram for single-phase electric motors
The installation and connection dimensions of single-phase electric motors completely coincide with the dimensions of general industrial electric motors of the corresponding size.
Single-phase 220V electric motors are widely used in a variety of industrial and household equipment: pumps, washing machines, refrigerators, drills and processing machines.
Varieties
There are two most popular types of these devices:
- Collector.
- Asynchronous.
The latter are simpler in design, but have a number of disadvantages, including difficulties in changing the frequency and direction of rotation of the rotor.
Asynchronous motor device
The power of this engine depends on design features and can vary from 5 to 10 kW. Its rotor is a short-circuited winding - aluminum or copper rods that are closed at the ends.
As a rule, a single-phase asynchronous electric motor is equipped with two windings offset by 90° relative to each other. In this case, the main (working) one occupies a significant part of the grooves, and the auxiliary (starting) one occupies the remaining part. The single-phase asynchronous electric motor received its name only because it has only one working winding.
Principle of operation
Flowing through the main winding creates a periodically changing magnetic field. It consists of two circles of the same amplitude, the rotation of which occurs towards each other.
2. Starters, for example, are divided by a value from 1 to 7, and the higher this indicator, the greater the current the contact system of these devices can withstand.
- 10A - 1.
- 25A - 2.
- 40A - 3.
- 63A - 4.
- 80A - 5.
- 125A - 6.
- 200A - 7.
3. After the starter size has been determined, you need to pay attention to the control coil. It can be 36B, 380B and 220B. It is advisable to focus on the last option.
5. The “Stop - Start” buttons are connected. They are powered from the input power contacts of the starter. For example, a phase is connected to the “Stop” button of a closed contact, then from it it goes to the start button of an open contact, and from the contact of the “Start” button to one of the contacts of the magnetic starter coil.
6. “Zero” is connected to the second terminal of the starter. To fix the on position of the magnetic starter, it is necessary to bypass the start button of the closed contact to the contact block of the starter, which supplies power from the “Stop” button to the coil.
Subsections of the material "Asynchronous three-phase motor 90L-2 · 2.2 kW · 2805 rpm · flange mounting (B5)":
| price, rub. |
|
7244 rub. |
| Additionally |
| Can be installed on electric motors |
|
| Additionally: |
| Full title | three-phase asynchronous electric motor |
| Marking | 90L-2 |
| Number of poles | 2 |
| Electric motor power, kW | 2.2 |
| Electric motor power, hp | 3 |
| Number of revolutions per minute | 2805 |
| Mounting type | flange mounting (B5) |
| Insulation class | insulation class F (insulation class H on request) |
| Security | degree of protection IP55 |
| Typical operating mode | operating mode S1 |
Basic parameters of the 90L-2 electric motor.
| Parameter | Meaning | Explanations |
| Nominal torque (C n), N*m | 7.49 | The rated torque of an electric motor depends on power and speed. It is calculated as the product of the force and the radius of the shaft. |
| Ratio of starting torque (C s) to nominal | 2.9 | Starting torque is the torque that the engine must develop in order to get off the ground and develop the installed power |
| Ratio of maximum torque (C max) to rated motor torque | 3 | The maximum torque produced by a motor of a certain rated power at a certain speed. Maximum torque also represents the amount of resistance at which the engine stops. |
| Rated current In, A | 4.75 | The current consumed by a motor when rated voltage is applied to achieve rated power. For another applied voltage, the current consumption is calculated proportional to that voltage. |
| Ratio of motor starting current I s to rated current | 5.2 | |
| Noise, dB | 72 | |
| Electric motor weight, kg | 14 |
Geometric dimensions of the 90L-2 asynchronous electric motor.
| G | 20 |  |
| D | 24 | |
| F | 8 | |
| D.H. | M8X19 | |
| E | 50 |
| A.C. | 195 |  |
| AD | 145 | |
| H | 90 | |
| KK | M20 | |
| L | 330 | |
| Q | 5 | M | 165 |
| N | 130 | |
| P | 200 | |
| R | 0 | |
| S | 12 | |
| T | 3.5 |
Additional options for the 90L-2 induction motor
Electric motor 90L-2 with ATDC brake
The 90L-2 asynchronous electric motor is optionally equipped with an electromagnetic brake that is activated when the power is turned off. The brake is built into the electric motor.
- The brake solenoid is powered by alternating current.
- There is a lever for manually releasing the electric motor from the brake.
- Insulation class F (insulation class H can be installed upon request)
On request, the 90L-2 electric motor can be equipped with an electromagnetic brake that is activated when the power is turned off. This brake is built into the 90L-2 electric motor.
- The brake electromagnet is powered DC 24V
- There is a lever for removing the 90L-2 electric motor from the brake by hand
- Thermal protection is built into the motor brake
- Insulation class F (class H optional)
- There is a button on the body to control the braking torque
- Higher response speed compared to ATDC brake
An encoder can be installed upon request for the 90L-2 electric motor.
An encoder is a device designed to convert the angle of rotation of an electric motor shaft into electrical signals that make it possible to determine the angle of rotation.
It often happens that the mechanics in washing machine, vacuum cleaner, electric drill completely fails, and it would be more profitable to buy a new one household appliances How to fix hopelessly outdated household electrical appliances.
Of the heap of spare parts remaining from these devices, as a rule, the most valuable element will be the electric motor, which can be put to good use by connecting it to a 220V network.
In such electrical appliances, a full-fledged three-phase motor is rarely found, and most likely there will be a single-phase commutator or asynchronous electric motor, which may have a fair margin of strength and bearing life for use as a drive for a pump, compressor, fan, sharpener, mini-machine, vegetable cutter, lawn mower etc.
This article will tell you how to connect a single-phase electric motor to a 220 V network, depending on its type.
Operating principle of a commutator motor
The brushed motor, found in washing machines and electric drills, has windings on the stator and rotor.
Brushed motor The rotor windings are wound in the form of frames and placed in special grooves, and they are switched using collector leads and contacts in the form of graphite brushes.
commutator motor rotor The rotor structure is designed in such a way that at any moment only one frame is energized, the magnetic field of which is perpendicular to the field of the stator winding.
The electromagnetic interaction of polar magnetic poles tends to rotate the rotor so that the direction of its magnetic field coincides with the stator field, like a compass needle.
But, as soon as the rotor turns to a certain angle, the contacts of the frame come out of contact with the brushes, and the next winding is turned on, and the process is repeated, creating a continuous torque.
Connection to a 220 V network for a commutator motor
The circuit of the commutator electric motor is designed in such a way that the directions of the currents in the rotor stator winding and the rotor frame always coincide, regardless of the phase of the alternating voltage. Due to the coincidence of the direction of the currents arising magnetic fields will always be perpendicular, which will cause the torque of the shaft.
Therefore, it is very important to install a jumper at the motor terminals to connect the stator and rotor windings in series. By swapping the leads of the stator or rotor windings, you can change the direction of rotation of the motor shaft.
connection diagram To complete the picture, you need to trace the path of the current - one of the terminals from the commutator brush is connected to a 220 V network (let's say phase, but it doesn't matter). The output of the other brush must be connected to one output of the stator using a jumper. The remaining output from the stator is connected to a 220 V network (zero), completing the circuit.
Operating principle of a single-phase asynchronous electric motor
Unlike a commutator motor, in a single-phase asynchronous electric motor with a squirrel-cage rotor at rest,
device asynchronous motor
in which currents are induced, creating a magnetic field that interacts with electromagnetic field coils, the vectors of the resulting forces (M, -M) balance each other. This means that when connected to the network, the motor shaft will not rotate, and an initial torque S is required to start it.
You can spin the shaft by hand and apply mains voltage, then the engine will pick up speed. Many people do this when starting a sharpener, but this method is completely unacceptable if you need to spin the rotating knives of a vegetable cutter or lawn mower.
Since in a three-phase electric motor the rotational torque is specified structurally using the arrangement of the windings and the phase displacement of the three-phase network, in a single-phase motor an additional starting winding is used for starting, thanks to which a rotational torque is created to displace the rotor.
Connection diagram 1 The phase shift of the current of the additional winding relative to the 220 V sinusoid is created using a capacitor.
Connection diagram 2 Connecting an asynchronous single-phase electric motor to the network.
On the single-phase housing asynchronous electric motor There must be a connection diagram indicating the terminals of the main and additional windings, as well as the capacitance of the capacitor.
Winding terminals But, if the circuit is lost somewhere, then you need to determine the working and starting windings by measuring and comparing the resistance - the main one should have less. To do this, you need to take a multimeter, set the measurement range in Ohms, and measure the resistance between the terminals one by one.
Determination of starting and operating windings Since these windings often have a common terminal, it is determined empirically - the sum of the resistances measured from a given winding wire must correspond to the total resistance of the windings connected in series. 
If the design of the motor allows, then the identity of the terminals can be determined visually - at the wires of the working winding cross section(thickness) greater.
working and starting windings The working winding is connected to a voltage of 220 V directly, and the starting winding is connected in series with the capacitor. If the windings are connected inside the motor, then such a circuit will not allow changing the direction of rotation. If four wires come out of the motor from two windings, then the direction of rotation will depend on the choice of leads for connecting them into a common tap.
Motor rotation selection There are electric motors with identical windings - they are called two-phase.
Single-phase motor modes
Since single-phase and two-phase motors require the use of a capacitor to start, such electric motors are called capacitor motors. There are several modes of operation of a capacitor motor:
- With a starting capacitor and an additional winding, which are connected only for the start time. The capacity is selected based on 70 μF per 1 kW of engine power;
- With a working capacitor with a capacity of 23-35 uF and an additional winding connected all the time;
- With a working and starting capacitor connected in parallel with the working one.
Used in cases where the engine is difficult to start. The capacity of the working capacitor is two to three times less than the starting capacitor rating (70 µF/1 kW).
Due to the complexity of the calculation formulas, it is customary to select containers based on the above proportions. In reality, having connected the electric motor, you need to monitor its operation and heating. If the engine heats up noticeably in mode with a working capacitor, then its capacity must be reduced. You need to select capacitors with an operating voltage of at least 450 V.
The engine with a starting capacitor is started manually using the control button,
or a circuit with two contactors, one of which (starting) does not have self-retaining and is held by the current of a closed push-button contact or time relay. Some capacitor motors have a centrifugal contact, used at start-up, that opens when the speed increases.
Connecting a three-phase motor to a 220 V network
In a similar way, using a capacitor, a three-phase motor is connected in a star or delta circuit.
The capacitance is calculated based on the operating voltage and current,
or rated motor power.
By analogy with a single-phase electric motor, in the case of difficult starting of a three-phase motor, a starting capacitor is used, the capacitance of which is two to three times higher than the operating rating.
Connecting three phase electric motor into a 220 V network using a starting capacitor, you must remember that with such a connection scheme, the motor will not work at full efficiency and will not develop maximum power.
For full-fledged work such an engine needs three phases, which can be obtained by running a 380 V network, or using a complex electronic circuit, designed for a specific power, generating phase displacement using powerful power semiconductor switches.
Having many different capacitors, but not finding desired value containers, you can connect them in parallel or in series.
By combining these connection methods, you can get closer to the required capacity rating.