Electricity has become the most popular form of energy only due to the electric motor. The engine, on the one hand, produces electrical energy, if its shaft is forced to rotate, and on the other hand, it is capable of converting electrical energy into rotational energy. Before the great Tesla, all networks were direct current, and motors, accordingly, were only constant current. Tesla used alternating current and built an alternating current motor. The transition to a variable motor was necessary to get rid of brushes - moving contacts. With the development of electronics, three-phase motors were given a new quality - speed control by thyristor drives. It is in terms of speed regulation that variables are inferior to constants. Of course, grinders have brushes and a commutator, but here it was simpler, but in refrigerators the engine is without brushes. Brushes are quite an inconvenient thing and all manufacturers of expensive equipment are trying to get around this issue.
Three-phase motors are the most common in industry. It is generally accepted, by analogy with motor constants, that an alternator also has poles. A pair of poles is one coil of winding, wound on a machine in the form of an oval and inserted into the slots of the stator. The more pairs of poles, the lower the engine speeds and the higher the torque on the rotor shaft. Each phase has several pairs of poles. For example, if the stator has 18 slots for winding, then there are 6 slots for each phase, which means each phase has 3 pairs of poles. The ends of the windings are brought out to a terminal block on which the phases can be connected either in a star or in a triangle. The motor has a data tag riveted on it, usually "star/delta 380/220V." This means that with a linear network voltage of 380 V, you need to turn on the motor in a star circuit, and with a linear 220 V - delta. The most common is the “star” circuit and this assembly of wires is hidden inside the motor, bringing only three ends of the phases to the windings.
All motors are attached to machines and devices using feet or a flange. Flange - for mounting the engine on the rotor shaft side in a suspended state. The paws are needed to fix the engine on a flat surface. In order to secure the engine, you need to take a sheet of paper, place your paws on this sheet and accurately mark the holes. After this, attach the sheet to the surface of the fastener and transfer the dimensions. If the engine is tightly connected to another part, then you need to align it relative to the fastener and shaft, and only then mark the fastening.
Engines come in the most different sizes. How larger sizes and mass, so more powerful engine. Whatever their size, they are all the same on the inside. A shaft with a key peeks out from the front side; on the other side, the rear is covered with an overlay plate-casing.
Usually terminal blocks are inserted into boxes on the engine. This allows for convenient installation, but due to many factors such pads are not available. Therefore, everything is done with reliable twisting.
The nameplate says about the engine power (0.75 kW), speed (1350 rpm), mains frequency (50 Hz), delta-star voltage (220/380), efficiency (72%), coefficient power (0.75).
The winding resistance and motor current are not indicated here. The resistance is quite low when measured with an ohmmeter. An ohmmeter measures the active component, but does not touch the reactive component, i.e. inductance. When the motor is connected to the network, the rotor stands still and all the energy of the windings is closed on it. The current in this case exceeds the rated current by 3 - 7 times. Then the rotor begins to accelerate under the influence of the rotating magnetic field, the inductance increases, the reactance increases and the current decreases. The smaller the motor, the higher its active resistance (200 - 300 Ohms) and the more it is not afraid of phase failure. Large motors have low active resistance (2 - 10 Ohms) and phase loss is fatal for them.
The formula for calculating the motor current is as follows.
If you substitute the values for the motor being disassembled, you will get the following current value. It must be taken into account that the resulting current is the same in all three phases. Here power is expressed in kW (0.75), voltage in kV (0.38 V), efficiency and power factor - in fractions of unity. The resulting current is in amperes.
Engine disassembly begins by unscrewing the impeller casing. The casing is needed for the safety of personnel - to prevent hands from sticking into the impeller. There was a case when a labor safety engineer, showing students a turning shop, said, “but you can’t do it like that,” and stuck his finger into a hole in the casing and came across a rotating impeller. The finger was cut off, the student remembered the lesson well. All impellers are equipped with casings. In enterprises with a low level of profitability, the impeller is also removed along with the casing.
The impeller is fixed on the shaft mounting plate. In large engines the impeller is metal, in small engines it is plastic. To remove it, you need to bend the tendril of the plate and carefully pull it from both sides with screwdrivers and pull it off the shaft. If the impeller breaks, then you definitely need to install another one, because without it, the cooling of the engine will be disrupted, which will cause overheating and ultimately cause a breakdown of the engine insulation. The impeller is made from two strips of tin. The tin is bent in half rings around the rotor, tightened with two bolts and nuts so that it sits tightly on the shaft, and the free ends of the tin are bent. You will get an impeller with four blades - cheap and cheerful.
An important element is the key on the motor shaft. The key is used to vibrate the rotor in the landing sleeve or gear. The key prevents the rotor from turning relative to the seating element. Hammering a dowel is a delicate matter. Personally, I first push the gear onto the rotor a little, drive it 1/3 full, and only then insert the key and hammer it in a little. Then I fit the entire gear together with the key. With this method, the key will not come out the other way. Here it's all about cutting a groove for the key. On the side closest to the engine body, the groove for the key looks like a slide along which the key slides out very smoothly and easily. There are other types of grooves - closed with an oval key, but square keys are more common.
There are bolts on both sides of the covers. To further disassemble the engine, you need to unscrew them and put them in a jar so as not to lose them. These bolts secure the covers to the stator. The bearings fit tightly in the covers. After unscrewing all the bolts, the covers should come off, but they stick and fit very tightly. Do not use crowbars or screwdrivers to grab the ears to secure the casing and rip off the covers. Although the covers are made of duralumin or cast iron, they are very brittle. The easiest way is to hit the shaft through a bronze extension, or lift the engine and hit the shaft hard on a hard surface. The puller can also break the lids.
If the lids give way, everything is fine. One will work well, the other needs to be knocked out through the engine with a stick. Bearings need to be knocked out with a stick reverse side covers. If the bearing does not sit in the cover, but dangles, then you need to take a core and punch the entire bearing seating surface. Then fill the bearing. The bearing should not cause beating or creaking. When making repairs, it’s a good idea to open the closed bearings with a knife, remove the old grease and add new grease to 1/3 of the volume.
Stator asynchronous motor alternating current is covered with windings on the inside. From the side of the key on the rotor, these windings are considered windings and this is in front of the engine. All ends of the coils come to the front windings and here the coils are collected in groups. To assemble the windings, you need to wind the coils, insert insulating spacers into the stator grooves, which will separate the steel stator from the insulated one. copper wire windings, lay the windings and cover the top with a second layer of insulation and fix the windings with insulating sticks, weld the ends of the windings, stretch the insulation over them, bring out the ends to connect the voltage, soak the entire stator in a bath of varnish and dry the stator in the oven.
The rotor of an asynchronous AC motor is short-circuited - there are no windings. Instead, a set of transformer steel round section with an asymmetrical shape. It can be seen that the grooves run in a spiral.
One of the methods for starting a three-phase linear voltage motor from a two-wire phase voltage network is to connect a working capacitor between the two phases. Unfortunately, the running capacitor cannot start the engine, you need to turn the motor by the shaft, but this is dangerous, but you can connect an additional starting capacitor in parallel with the running capacitor. With this approach, the engine will start. However, when the rated speed is reached, the starting capacitor must be disconnected, leaving only the working one.
The working capacitor is selected at the rate of 22 μF per 1 kW of motor. The starting capacitor is selected at the rate of 3 times larger than the working capacitor. If there is a 1.5 kW motor, then Cp = 1.5 * 22 = 33 µF; Sp = 3*33 = 99 uF. You only need a paper capacitor with a voltage of at least 160 V when the windings are connected in a star and 250 V when the windings are connected in a delta. It is worth noting that it is better to use the connection of the windings in a star - more power.
The Chinese do not face the problem of certification or registration, so all innovations from the magazines “Radio” and “Modelist Kstruktor” are made instantly. For example, like this three phase motor, which can be turned on at 220 V and in automatic mode. To do this, a horseshoe-shaped plate with a normally closed contact is located next to the front windings.
IN distribution box Instead of the terminal block, capacitors are inserted. One at 16 uF 450 V is working, the second at 50 uF 250 V is starting. Why there is such a difference in voltage is unclear, apparently they shoved what was there.
On the engine rotor there is a spring-loaded piece of plastic, which, under the influence of centrifugal force, presses on the horseshoe-shaped contact and opens the starting capacitor circuit.
It turns out that when the engine is turned on, both capacitors are connected. The rotor spins up to certain speeds, at which the Chinese consider that the start is complete, the plate on the rotor moves, pressing on the contact and turning off the starting capacitor. If you leave the start capacitor connected, the motor will overheat.
To start the engine from a 380 V system, you need to disconnect the capacitors, ring the windings and connect the three-phase network voltage to them.
Good luck everyone.
A single-phase asynchronous electric motor with a squirrel-cage rotor must have a starting and operating winding. Their calculation is carried out in the same way as the calculation of the windings of three-phase asynchronous motors.
Number of conductors in the groove of the working winding (fits into 2/3 of the stator grooves)
N р = (0.5 ÷ 0.7) x N x U s / U,
where N is the number of conductors in the slot of a three-phase electric motor;
U c - single-phase network voltage, V;
U is the rated phase voltage of a three-phase motor, V.
Lower coefficient values are taken for engines of higher power (about 1 kW) with short-term and intermittent operating modes.
Diameter (mm) of wire on copper of working winding
,
where d is the diameter of the copper wire of a three-phase motor, mm.
The starting winding fits into 1/3 of the slots.
The most common are two options for starting windings: with bifilar coils and with additional external resistance.
The winding with bifilar coils is wound from two parallel conductors with in different directions current (inductive leakage resistance of bifilar windings is close to zero).
Start winding with bifilar coils
1. Number of conductors in the groove for the main section
N p ′ = (1.3 ÷ 1.6) N r.
2. Number of conductors in the groove for the bifilar section
N p ′′ = (0.45 ÷ 0.25) N p ′.
3. Total number conductors in the groove
N p = N p ′ + N p ′′
4. Wire cross-section
s p ′ = s p ′′ ≈ 0.5s p, where s p is the cross-section of the working winding.
Start winding with external resistance
1. Number of conductors in the slot
N p = (0.7 ÷ 1) N r.
2. Wire cross-section
s p = (1.4 ÷ 1) s p.
3. Additional resistance (finally clarified during engine testing) (Ohm)
R d = (1.6 ÷ 8) x 10 -3 x U s / s p,
where U c is the voltage of a single-phase network, V.
To obtain a large starting torque, preference should be given to the second version of the starting winding, since in this case it is possible to obtain the highest starting torque by changing the external resistance.
The current of a single-phase electric motor is determined by the calculated cross-section for the working winding and the current density in the winding of a three-phase motor I 1 = s p δ, where δ is the permissible current density (6-10 A/mm²).
Single-phase electric motor power P = U x I x cos φ x η
Table. Product of cos φ and efficiency 
When the motor power is over 500 W, the values of η and cos φ can be taken as for three-phase asynchronous motors, reducing the power of a single-phase motor according to the above formula by 10-15%.
An example of converting a three-phase motor to a single-phase winding
Convert a three-phase motor to a single-phase winding. Electric motor power 0.125 kW, voltage 220/380 V, synchronous speed 3000 rpm; the number of conductors in the groove is 270, the number of stator grooves is 18. Wire brand PEV-2, copper diameter 0.355 mm, cross-section 0.0989 mm 2. The specified voltage of a single-phase motor is 220 V.
1. The working winding occupies 2/3 of the slots, and the starting winding occupies 1/3 of the slots
(z p = 12, z p = 6).
2. Number of conductors in the groove of the working winding
N p = 0.6 x N x U s / U = 0.6 x 270 x 220 / 220 = 162.
3. Diameter of the working winding wire on copper 
mm,
where d = 0.355 mm is the diameter of the copper wire of a three-phase motor.
We take PEV-2 wire, d p = 0.45 mm, s p = 0.159 mm².
4. We take the starting winding with external resistance.
5. Number of conductors in the slot
N p = 0.8 x N p = 0.8 x 162 ≈ 128.
6. Cross-section of starting winding wires
s p ′ = 1.1 x s p = 1.1 x 0.159 = 0.168 mm².
We take PEV-2 wire with a copper diameter
d p = 0.475 mm, s p = 0.1771 mm².
7. Additional resistance
R d = 4 x 10 -3 x U s / s p = 4 x 10 -3 x 220 / 0.1771 ≈ 5 Ohm.
8. Single-phase motor current
at δ = 8 A/mm² I 1 = s р δ = 0.159 x 8 = 1.28 A.
9. Single-phase motor power
P = U x I x cos φ x η = 220 x 1.28 x 0.4 = 110 W.
It consists of two main parts - the stator and the rotor. The stator is the stationary part, the rotor is the rotating part. The rotor is placed inside the stator. There is a small distance between the rotor and stator, called an air gap, usually 0.5-2 mm.
Asynchronous motor stator
Asynchronous motor rotor
Stator consists of a body and a core with a winding. The stator core is assembled from thin sheet technical steel, usually 0.5 mm thick, coated with insulating varnish. The laminated core design contributes to a significant reduction in eddy currents arising during the process of magnetization reversal of the core by a rotating magnetic field. The stator windings are located in the slots of the core.
Housing and stator core of an asynchronous electric motor
Design of a laminated core of an asynchronous motor
Rotor consists of a core with short-circuited winding and shaft. The rotor core also has a laminated design. In this case, the rotor sheets are not varnished, since the current has a low frequency and the oxide film is sufficient to limit eddy currents.
Operating principle. Rotating magnetic field
The principle of three-phase operation is based on the ability of a three-phase winding, when connected to a three-phase current network, to create a rotating magnetic field.
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Rotating magnetic field of an asynchronous electric motor
The rotation frequency of this field, or the synchronous rotation frequency, is directly proportional to the frequency of the alternating current f 1 and inversely proportional to the number of pole pairs p of the three-phase winding.
,
- where n 1 is the rotation frequency of the stator magnetic field, rpm,
- f 1 – alternating current frequency, Hz,
- p – number of pole pairs
Rotating magnetic field concept
To understand the rotating magnetic field phenomenon better, consider a simplified three-phase winding with three turns. Current flowing through a conductor creates a magnetic field around it. The figure below shows the field created by three-phase alternating current at a specific point in time
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Magnetic field of a straight conductor with DC
Magnetic field created by the winding
The components of alternating current will change over time, causing the magnetic field they create to change. In this case, the resulting magnetic field of the three-phase winding will take different orientations, while maintaining the same amplitude.
Magnetic field created by three-phase current at different times 
Current flowing in the turns of the electric motor (shift 60°)
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The effect of a rotating magnetic field on a closed loop
Now let's place a closed conductor inside a rotating magnetic field. A changing magnetic field will give rise to an electromotive force (EMF) in the conductor. In turn, the EMF will cause a current in the conductor. Thus, in a magnetic field there will be a closed conductor with a current, on which a force will act accordingly, as a result of which the circuit will begin to rotate.
The influence of a rotating magnetic field on a closed conductor carrying current Squirrel-cage rotor of an asynchronous motor
This principle also works. Instead of a current-carrying frame, inside the asynchronous motor there is a squirrel-cage rotor whose design resembles a squirrel wheel. Squirrel cage rotor consists of rods short-circuited at the ends with rings.
Squirrel cage rotor most widely used in induction motors (shown without shaft and core) Three-phase alternating current, passing through the stator windings, creates a rotating magnetic field. Thus, also as described earlier, a current will be induced in the rotor bars, causing the rotor to start rotating. In the figure below you can notice the difference between the induced currents in the rods. This occurs due to the fact that the magnitude of the change in the magnetic field differs in different pairs of rods, due to their different locations relative to the field. The change in current in the rods will change with time.
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Rotating magnetic field penetrating a squirrel-cage rotor
You may also notice that the rotor arms are tilted relative to the axis of rotation. This is done in order to reduce the higher harmonics of the EMF and get rid of torque ripple. If the rods were directed along the axis of rotation, then a pulsating magnetic field would arise in them due to the fact that the magnetic resistance of the winding is much higher than the magnetic resistance of the stator teeth.
Slip of an asynchronous motor. Rotor speed
A distinctive feature of an asynchronous motor is that the rotor speed n 2 is less than the synchronous speed of the stator magnetic field n 1 .
This is explained by the fact that the EMF in the rotor winding rods is induced only when the rotation speeds n 2 are unequal Let's consider the case when the rotor rotation frequency coincides with the rotation frequency of the stator magnetic field. In this case, the relative magnetic field of the rotor will be constant, thus no EMF, and therefore no current, will be created in the rotor rods. This means that the force acting on the rotor will be zero. This will slow down the rotor. After which an alternating magnetic field will again act on the rotor rods, thus the induced current and force will increase. In reality, the rotor will never reach the rotation speed of the stator's magnetic field. The rotor will rotate at a certain speed which is slightly less than the synchronous speed. The slip of an asynchronous motor can vary in the range from 0 to 1, i.e. 0-100%. If s~0, then this corresponds to the idle mode, when the engine rotor experiences practically no counteracting torque; if s=1 - short circuit mode, in which the motor rotor is stationary (n 2 = 0). Slip depends on the mechanical load on the motor shaft and increases with its growth. The slip corresponding to the rated load of the motor is called rated slip. For low and medium power asynchronous motors, the rated slip varies from 8% to 2%. Field-oriented control allows you to smoothly and accurately control the movement parameters (speed and torque), but its implementation requires information about the direction and vector of the engine rotor flux linkage. To increase efficiency and reduce brush wear, some ADFRs contain a special device (short-circuit mechanism), which, after starting, lifts the brushes and closes the rings. With rheostatic starting, favorable starting characteristics are achieved, since high torque values are achieved at low starting current values. Currently, ADDFs are being replaced by a combination of a squirrel-cage induction motor and a frequency converter. Three-phase electric motors have become widespread both in industrial use and for personal purposes due to the fact that they are much more efficient than motors for a conventional two-phase network. A three-phase induction motor is a device consisting of two parts: a stator and a rotor, which are separated by an air gap and have no mechanical connection with each other. The stator has three windings wound on a special magnetic core, which is made from plates of special electrical steel. The windings are wound in the stator slots and are located at an angle of 120 degrees to each other. The rotor is a bearing-supported structure with an impeller for ventilation. For electric drive purposes, the rotor may be in direct connection with the mechanism or through gearboxes or other mechanical energy transmission systems. Rotors in asynchronous machines can be of two types: The main driving force in a three-phase asynchronous motor is the rotating magnetic field, which arises, firstly, due to the three-phase voltage, and, secondly, the relative position of the stator windings. Under its influence, currents arise in the rotor, creating a field that interacts with the stator field.
An asynchronous motor is called because the rotor speed lags behind the rotation speed of the magnetic field; the rotor constantly tries to “catch up” with the field, but its frequency is always lower. In order to make the engine work, there are several different connection schemes, the most used among them are star and delta. The electric motor plate indicates the possibility of connection using the “star” method in the form of a Y symbol, and it may also indicate whether it can be connected using another scheme. A connection according to this scheme can be with a neutral, which is connected to the connection point of all windings. This approach allows you to effectively protect the electric motor from overloads using a four-pole circuit breaker.
A star connection does not allow an electric motor adapted for 380 volt networks to develop full power due to the fact that each individual winding will have a voltage of 220 volts. However, such a connection prevents overcurrent and the motor starts smoothly. The terminal box will immediately show when the motor is connected in a star configuration. If there is a jumper between the three terminals of the windings, then this clearly indicates that this particular circuit is used. In any other cases, a different scheme applies. The winding terminals are connected as follows: C4 is connected to C2, C5 to C3, and C6 to C1. With the new marking it looks like this: U2 connects to V1, V2 to W1, and W2 to U1. In three-phase networks, there will be a linear voltage of 380 volts between the terminals of the windings, and a connection to the neutral (working zero) is not required. This scheme also has the peculiarity that large inrush currents arise, which the wiring may not withstand. In practice, a combined connection is sometimes used, when a star connection is used at the start-up and acceleration stages, and in operating mode special contactors switch the windings to a delta circuit. In the terminal box, a delta connection is determined by the presence of three jumpers between the winding terminals. On the motor nameplate, the possibility of delta connection is indicated by the symbol Δ, and the power developed in star and delta configurations can also be indicated. Three-phase asynchronous motors occupy a significant part among electricity consumers due to their obvious advantages.
Any tool is subject to overload and various damages. You can drop a power tool or spill liquid on it, resulting in rust appearing on the windings, which will render the engine unusable. Rewinding an electric motor with your own hands is quite simple, but you will need a minimum set of tools. The most important thing is that you need skill and experience in repairs. If the power tool is used incorrectly, it is the rotor winding that takes the full impact. The wire from which it is made may break or burn. But if you replace the winding, the tool life will increase significantly. In order to independently rewind the armature of an electric motor with your own hands, you will need the following tools and devices. Before starting work, it is necessary to accurately determine the damage. To do this, you need to visually inspect the electric motor and check whether there is voltage going to the collector. Carry out diagnostics of the start button, ring it using a multimeter. Only if the power circuit is fully operational, it is necessary to disassemble the electric motor and repair it. Before starting work, you need to study the instructions for rewinding electric motors. If you do this yourself, it will take at least 4 hours, and that’s just to rewind the armature. Before starting repairs, you must complete the following steps. Left or right reset is also sometimes used. If winding occurs with a reset to the right, the coil goes to the right of the beginning of the winding. For example, if there are 12 grooves in the armature, the winding step is 1-6 and the reset is made to the right, the winding is laid in the first, then in the eighth and fastening is carried out in the second grooves. All these points must be taken into account, otherwise after repair it will turn out that the electric motor rotates in the other direction. In order to rewind email. engines in everyday conditions, it is necessary to remember, write down, or photograph each stage of the work. This will greatly facilitate repairs and avoid inaccuracies during assembly. To determine the winding direction and the initial groove, you need to find a coil that is not covered by others. She is the last one. If the winding is laid to the right, then the initial groove is located to the right of the outer coil. This is where you need to start laying the wire. Only in this way can you achieve the most accurate winding, very close to the factory one. If the initial winding is symmetrical, and coils are placed in pairs, then there will be two initial slots. You can find them in exactly the same way as in the previous case. The master must find out how many turns of wire are laid in one groove and in the entire coil. To do this, you need to separate the coil located on top and count how many turns there are in it. If necessary, disassemble using a gas torch. The number of turns in the groove directly depends on: After calculation, it is necessary to prepare the collector; dismantling it is not required. To do this, you simply need to measure the resistance value between the housing and the lamellas. The resistance should be in the range of 200-250 kOhm. After this, you need to completely dismantle the old conductor; to do this, remove the winding. Carefully protect all grooves and the armature body. Carbon deposits and burrs must be sanded with sandpaper. After this, it is necessary to cut rectangular sections from cardboard corresponding to the dimensions of the grooves in the anchor. After this, you can begin winding new conductors. The circuit must be the same as the factory one. Start laying from the initial groove, observing the reset and winding pitch. Fastening is done using cotton threads directly at the collector. Synthetic threads are not recommended for use as they are susceptible to burning. After completing all work, it is necessary to check the windings for interturn short circuits and breaks. If there are no breakdowns, then it is necessary to apply epoxy resin or varnish to the winding. To speed up the process, you need to place the anchor in the oven, setting the temperature to 80 degrees. Drying must be carried out for at least 20 hours. In order for the power tool to work as efficiently as possible after repair, you will need to do balancing. Since all work is performed at home, certain recommendations must be followed. Rewinding an electric motor with your own hands is quite simple; balancing it will be much more difficult. After balancing, the anchor should be motionless. In order to equalize the sides of the rotor, it is necessary to hang small weights made of plasticine on it. Only after you achieve balance, you need to remove the plasticine weights, weigh them, and solder the metal. After this, be sure to recheck the balancing. Asynchronous motors can be single-phase or three-phase. There are specifics to checking these machines. To find out more accurate engine parameters, you need to read the information located on its body. It contains a plate with all operating parameters, and sometimes even with winding connection diagrams. Before rewinding the stator of an asynchronous electric motor, it is necessary to completely disassemble it. To do this, you will need to use a puller, since the covers are mounted on the bearings very tightly. Try to carry out all work as carefully as possible to prevent destruction of the cover and damage to the winding. Squirrel-cage rotors very rarely break, so there is no need to touch it during repairs. Only the windings on the stator need to be changed. If there is blackening on the wires, this indicates a breakdown in the engine. All connections in asynchronous motors are practically invisible, since they are very well insulated, because they are fastened with a bandage. After disassembly, be sure to remove the old winding. To do this, you will need to use a sharp knife to cut off all the ropes and get rid of the glue. The wires are cleaned as much as possible from dirt, without damaging the electrical connections. It is advisable to take photographs of all connections so that everything is done correctly during assembly. Be sure to draw up a diagram of the connection of all windings; you can use reference books for this. Then you need to knock out the stakes made of PCB or wood, which are located inside the stator grooves. After this, remove the gaskets, freeing the wires. Find the outermost wire, take it to the middle of the stator, it should completely peel off from the winding. After this, unwind the next turn until the groove is completely free. There are several ways to rewind the stator of an asynchronous electric motor, but when choosing any of them, be sure to remember each step during disassembly. This will make the repair easier, and significantly. For winding, you will need a copper wire in varnish insulation; its cross-section should be the same as on the electric motor being repaired. Make sure that there is no damage to the housing and magnetic circuit of the electric motor. After this, it is necessary to make sleeves and install them in the grooves on the stator. In order not to count the number of turns, or to determine the thickness, strength and heat resistance of materials for the manufacture of sleeves, you can use reference literature. To do this, you need to know the type and model of the asynchronous motor. All work in specialized workshops is carried out on machines. The machine even calculates the number of turns. But how can you rewind an electric motor at home if there are no such conditions? You will have to calculate everything yourself, or take all the data from the service book for the electric motor. After placing all the windings in the grooves, you need to insert insulators between the coils. The bandage must be carried out on the back side of the stator. Pass the thread through all the loops, while trying to tighten all the insulators and wires. Make sure that the insulating plates do not slip out of place. Upon completion, be sure to carry out diagnostics of the entire winding, then warm up the stator and apply a special varnish. The stator must be completely immersed in varnish. This is how you can achieve maximum mechanical strength of the windings, because fill the voids and grooves. At this point, the rewinding of the electric motor with your own hands is completed, you can begin operation.
,Energy conversion
Field-oriented control of an asynchronous electric motor using a rotor position sensor According to the method of obtaining information about the position of the flux linkage of the electric motor rotor, the following are distinguished:
Field-oriented control of an asynchronous electric motor without a rotor position sensor Of course, three-phase machines are not without their drawbacks.
Various schemes for connecting asynchronous motors to a 380 volt network
How to properly connect a three-phase star motor
This connection method is used mainly in three-phase networks with a linear voltage of 380 volts. The ends of all windings: C4, C5, C6 (U2, V2, W2) are connected at one point. To the beginnings of the windings: C1, C2, C3 (U1, V1, W1), - phase conductors A, B, C (L1, L2, L3) are connected through the switching equipment. In this case, the voltage between the beginnings of the windings will be 380 volts, and between the point of connection of the phase conductor and the point of connection of the windings will be 220 volts.We make the connection according to the “triangle” scheme
In order for a three-phase motor to develop its maximum rated power, a connection called “triangle” is used. In this case, the end of each winding is connected to the beginning of the next one, which in reality forms a triangle in the circuit diagram.A clear and simple explanation of the operating principle in the video
Tools and accessories
Preparing to Rewind
Winding direction and starting groove
Peculiarities
Winding a new wire
Rotor balancing
Features of testing asynchronous motors
Disassembling an asynchronous motor
Removing the winding
Wire winding
Completion of winding