In a three-phase network, there are usually 4 wires (3 phases and zero). There may also be a separate ground wire. But there are also without a neutral wire.
How to determine the voltage in your network?
Very simple. To do this, you need to measure the voltage between phases and between zero and phase.
In 220/380 V networks, the voltage between phases (U1, U2 and U3) will be 380 V, and the voltage between zero and phase (U4, U5 and U6) will be 220 V.
In 380/660V networks, the voltage between any phases (U1, U2 and U3) will be 660V, and the voltage between zero and phase (U4, U5 and U6) will be 380V.
Asynchronous electric motors have three windings, each of which has a beginning and an end and corresponds to its phase. Winding designation systems can be different. In modern electric motors, the winding designation system U, V and W is adopted, and their conclusions are indicated by the number 1 at the beginning of the winding and the number 2 at its end, that is, the U winding has two leads: U1 and U2, the V winding is V1 and V2, and the W winding is W1 and W2.
However, old induction motors made during the USSR and having the old Soviet marking system are still in operation. In them, the beginnings of the windings are designated C1, C2, C3, and the ends - C4, C5, C6. This means that the first winding has terminals C1 and C4, the second - C2 and C5, and the third - C3 and C6.
The windings of three-phase electric motors can be connected in two different ways: star (Y) or delta (Δ).
The name of the connection scheme is due to the fact that when connecting the windings according to this scheme (see the figure on the right), it visually resembles a three-beam star.
As can be seen from the motor connection diagram, all three windings are connected together at one end. With this connection (network 220/380 V), a voltage of 220 V is separately applied to each winding, and a voltage of 380 V is applied to two windings connected in series.
The main advantage of connecting an electric motor according to the star circuit is small starting currents, since the supply voltage of 380 V (interphase) consumes 2 windings at once, in contrast to the triangle circuit. But with such a connection, the power of the supplied electric motor is limited (mainly for economic reasons): usually, relatively weak electric motors are turned on in a star.
The name of this scheme also comes from the graphic image (see right figure):
As can be seen from the electric motor connection diagram - “triangle”, the windings are connected in series to each other: the end of the first winding is connected to the beginning of the second, and so on.
That is, a voltage of 380 V will be applied to each winding (when using a 220/380 V network). In this case, more current flows through the windings; motors of greater power are usually switched on in a triangle than when connected in a star (from 7.5 kW and above).
The sequence of actions is as follows:
1.
To begin with, we find out what voltage our network is designed for.
2.
Next, we look at the plate that is on the electric motor, it may look like this (star Y / triangle Δ):
(~ 1, 220V)
220V/380V (220/380, Δ / Y)
(~ 3, Y, 380V)
Three-phase motor
(380V / 660V (Δ / Y, 380V / 660V)
3.
After identifying the network parameters and the parameters of the electrical connection of the motor (star Y / delta Δ), we proceed to the physical electrical connection of the motor.
4.
To turn on a three-phase electric motor, you need to simultaneously apply voltage to all 3 phases.
A fairly common cause of failure of the electric motor is operation in two phases. This can happen due to a faulty starter, or during phase imbalance (when the voltage in one of the phases is much less than in the other two).
There are 2 ways to connect an electric motor:
- use of a circuit breaker or motor protection circuit breaker
These devices, when turned on, supply voltage to all 3 phases at once. 
We recommend installing the MS series motor protection circuit breaker, as it can be adjusted exactly to the operating current of the motor, and it will sensitively monitor its increase in case of overload. This device at the time of start-up makes it possible to work for some time at an increased (starting) current without turning off the engine.
The usual circuit breaker is required to be set in excess of the rated current of the electric motor, taking into account the starting current (2-3 times higher than the nominal).
Such an automatic machine can turn off the engine only in the event of a short circuit or jamming, which often does not provide the necessary protection.
Starter use 
The starter is an electromechanical contactor that closes each phase with the corresponding motor winding.
The contactor mechanism is driven by an electromagnet (solenoid).
Electromagnetic starter device:
The magnetic starter is quite simple and consists of the following parts:
(1) Solenoid coil
(2) Spring
(3) Movable frame with contacts (4) for connecting the mains supply (or windings)
(5) Fixed contacts for connecting the motor windings (power supply).
When power is applied to the coil, the frame (3) with contacts (4) is lowered and closes its contacts to the corresponding fixed contacts (5).
Typical motor connection diagram using a starter:
5.
Check if the shaft is turning in the correct direction.
If you want to change the direction of rotation of the motor shaft, then you just need to swap any 2 phases. This is especially important when powering centrifugal electric pumps with a strictly defined direction of rotation of the impeller.
From all of the above, it becomes clear that in order to control a three-phase pump motor in automatic mode using a float switch, it is IMPOSSIBLE to simply break one phase, as is done with mono-phase motors in a single-phase network.
The easiest way is to use a magnetic starter for automation.
In this case, it is sufficient to build a float switch in series with the power supply circuit of the starter coil. When the circuit is closed by a float, the starter coil circuit will be closed, and the electric motor will turn on, when it is opened, the electric motor will be turned off.
Usually, to connect to a single-phase 220V network, special motors are used that are designed to connect to just such a network, and there are no issues with their power supply, because. for this, you just need to insert the plug (most domestic pumps are equipped with a standard Schuko plug) into the socket
Sometimes it is required to connect a three-phase electric motor to a 220 V network (if, for example, it is not possible to conduct a three-phase network).
The maximum possible power of the electric motor, which can be connected to a single-phase 220 V network, is 2.2 kW.
The easiest way is to connect the electric motor through a frequency converter designed to be powered by a 220 V network.
It should be remembered that a 220 V frequency converter outputs 3 phases of 220 V each. That is, you can only connect an electric motor to it that has a supply voltage of 220 V of a three-phase network (usually these are motors with six contacts in a junction box, the windings of which can be connected both in a star and in a triangle). In this case, it is required to connect the windings in a triangle.
An even simpler connection of a three-phase electric motor to a 220 V network using a capacitor is possible, but such a connection will lead to a loss of motor power by approximately 30%. The third winding is powered through a capacitor from any other.
We will not consider this type of connection, since this method does not work normally with pumps (either the engine does not start at startup, or the electric motor overheats due to a decrease in power).
At present, quite actively everyone began to use frequency converters to control the rotational speed (revs) of the electric motor.
This allows not only to save energy (for example, when using frequency regulation of pumps for water supply), but also to control the supply of positive displacement pumps, turning them into dosing pumps (any positive displacement pumps).
But very often, when using frequency converters, they do not pay attention to some of the nuances of their application:
Frequency adjustment, without modification of the electric motor, is possible within the frequency adjustment +/- 30% of the operating one (50 Hz),
- with an increase in the rotational speed of more than 65 Hz, it is necessary to replace the bearings with reinforced ones (now with the help of a frequency converter it is possible to raise the current frequency to 400 Hz, conventional bearings simply fall apart at such speeds),
- when the speed decreases, the built-in fan of the electric motor starts to work inefficiently, which leads to overheating of the windings.
Due to the fact that they do not pay attention to such “little things” when designing installations, very often electric motors fail.
For operation at low frequency, it is MANDATORY required to install an additional fan for forced cooling of the electric motor.
Instead of a fan cover, a forced cooling fan is installed (see photo). In this case, even with a decrease in the main engine shaft speed,
an additional fan will provide reliable cooling of the electric motor.
We have extensive experience in retrofitting electric motors for low frequency operation.
In the photo you can see screw pumps with additional fans on electric motors.
These pumps are used as dosing pumps in food production.
We hope that this article will help you properly connect the electric motor to the network yourself (or at least understand that you are not an electrician, but a “generalist”).
Technical Director
LLC "Pumps Ampika"
Moiseev Yuri.
It must be connected to a 220 V home network. Since the engine will not start, it is necessary to change some details in it. This can be easily done on your own. Even though the efficiency will decrease somewhat, this approach is justified.
To figure out how to connect an electric motor from 380 to find out what 380 volt power means.
Three-phase motors have many advantages over household single-phase motors. Therefore, their application in industry is extensive. And the point is not only in power, but also in efficiency. They also provide starting windings and capacitors. This simplifies the design of the mechanism. For example, the starting protective relay of the refrigerator monitors how many windings are connected. And in a three-phase motor, this element is no longer necessary.
This is achieved by three phases, during which an electromagnetic field rotates inside the stator.
When the field inside the stator rotates, the rotor also moves. The turns do not match the 50 Hertz of the network due to the fact that there are more windings, the number of poles is different, and slippage occurs for various reasons. These indicators are used to regulate the rotation of the motor shaft.
All three phases have a value of 220 V. However, the difference between any two of them at any time will be different from 220. This will turn out to be 380 Volts. That is, the engine is used for operation, while there is a phase shift of one hundred and twenty degrees.
Because it is impossible to connect a 380 to 220 Volt electric motor directly, you have to use tricks. The capacitor is considered the simplest way. When the capacitance passes the phase, the latter changes by ninety degrees. Although it does not reach one hundred and twenty, this is enough to start and operate a three-phase motor.
To implement the task, it is necessary to understand how the windings are arranged. Usually the case is protected by a casing, and wiring is located under it. After removing it, you need to examine the contents. You can often find a wiring diagram here. In order for the network 380-220 to take place, switching in the form of a star is used. The ends of the windings are at a common point, which is called neutral. Phases are fed to the opposite side.
"Star" will have to change. To do this, the motor windings must be connected in a different shape - in the form of a triangle, combining them at the ends with each other.
The schema might look like this:
It is clear that the phase shift will be ninety and forty-five degrees. Because of this, the rotation will not be uniform. In addition, the phase shape on the second winding will not be sinusoidal. Therefore, after it is possible to connect a three-phase electric motor to 220 volts, it will not be able to be implemented without power loss. Sometimes the shaft even sticks and stops spinning.
After a set of revolutions, the starting capacity will no longer be needed, since the resistance to movement will become insignificant. To discharge the capacitance, it is shortened by a resistance through which the current will no longer pass. For the correct choice of working and starting capacity, first of all, it must be taken into account that the working capacitor voltage must significantly overlap 220 volts. It should be at least 400 V. You also need to pay attention to the wires so that the currents are intended for a single-phase network.
If the working capacity is too low, the shaft will stick, so the initial acceleration is used for it.
Working capacity also depends on the following factors:
This capacity also depends on the load.
It is known that an electric motor of 380 V at 220 Volts will work better if the voltages are obtained with equal values. For this, the winding connected to the network does not need to be touched, but the potential is measured on both others.
The asynchronous motor has its own It is necessary to determine the minimum at which it will start rotating. After that, the value is gradually increased until all the windings are aligned.
But when the engine spins up, it may turn out that equality is violated. This is due to the reduction in resistance. Therefore, before connecting the electric motor from 380 to 220 Volts and fixing this, you need to equalize the values \u200b\u200band with the unit running.
The voltage may be higher than 220 V. Look to ensure stable docking of the contacts, and there is no power loss or overheating. Switching is best done on special terminals with fixed bolts. After connecting the electric motor from 380 to 220 Volts, it turned out with the necessary parameters, the casing is again put on the unit, and the wires are passed through the rubber seal on the sides.
Often, after assembly, it is found that the shaft rotates in the wrong direction. The direction needs to be changed.
To do this, the third winding is connected through a capacitor to the threaded terminal of the second stator winding.
It happens that due to long-term operation, engine noise appears over time. However, this sound is of a completely different kind compared to the hum when connected incorrectly. It happens over time and the vibration of the motor. Sometimes you even have to turn the rotor with force. This is usually caused by wear on the bearings, resulting in too large clearances and noise. Over time, this can lead to jamming, and later to damage to engine parts.
It is better not to allow this, otherwise the mechanism will become unusable. It is easier to replace the bearings with new ones. Then the electric motor will last for many more years.
There are often cases when it is necessary to connect an electric motor to a 220 volt network - this happens when trying to attach equipment to your needs, but the circuit does not meet the technical specifications indicated in the passport of such equipment. We will try to analyze in this article the main methods for solving the problem and present several alternative circuits with a description for connecting a single-phase electric motor with 220 volt condensate.
Why is this happening? For example, in a garage, you need to connect a 220 volt asynchronous electric motor, which is designed for three phases. At the same time, it is necessary to maintain the efficiency (efficiency factor), this is done if there is simply no alternative (in the form of an engine), because in a three-phase circuit a rotating magnetic field is easily formed, which provides the conditions for the rotation of the rotor in the stator. Without this, the efficiency will be less compared to a three-phase connection scheme.
When there is only one winding in single-phase motors, we observe a picture when the field inside the stator does not rotate, but pulsates, that is, the push to start does not occur until the shaft is untwisted with one's own hand. In order for the rotation to take place independently, we add an auxiliary starting winding. This is the second phase, it is moved 90 degrees and pushes the rotor when turned on. In this case, the motor is still connected to the network with one phase, so that the name of single-phase is preserved. Such single-phase synchronous motors have a working and starting winding. The difference is that the starter only works when turned on, starting the rotor, working for only three seconds. The second winding is on all the time. In order to determine which is which, you can use the tester. In the figure you can see their relationship with the scheme as a whole.
Connecting a 220 volt electric motor: the motor is started by supplying 220 volts to the working and starting windings, and after gaining the required speed, you must manually turn off the starting one. In order to shift the phase, ohmic resistance is necessary, which is provided by the inductance capacitors. There is resistance both in the form of a separate resistor, and in part of the starting winding itself, which is performed using the bifilar technique. It works like this: the inductance of the coil is maintained, and the resistance becomes greater due to the elongated copper wire. Such a scheme can be seen in Figure 1: connecting a 220 volt electric motor.
Figure 1. Wiring diagram for a 220 volt motor with a capacitor
There are also motors in which both windings are continuously connected to the network, they are called two-phase, because the field inside rotates, and the capacitor is provided to shift the phases. For such a circuit to work, both windings have a wire with an equal cross section to each other.
Where can you meet in everyday life?
Electric drills, some washing machines, rotary hammers and grinders have a synchronous commutator motor. It is able to work in networks with a single phase, even without starting mechanisms. The scheme is as follows: ends 1 and 2 are connected with a jumper, the first originates in the armature, the second in the stator. The two tips that remain must be connected to a 220 volt power supply.
Connecting a 220 volt electric motor with a starting winding
Attention!
There is another option for connecting an electric motor with a power of 380 volts, which sets in motion without load. This also requires a working capacitor.
One end is connected to zero, and the other end is connected to the output of a triangle with serial number three. To change the direction of rotation of the electric motor, it is worth connecting it to the phase, and not to zero.
Wiring diagram for a 220 volt electric motor through capacitors
In the case when the engine power is more than 1.5 kilowatts or it works immediately with a load at the start, it is necessary to install the starting capacitor in parallel with the working capacitor. It serves to increase the starting torque and turns on for only a few seconds during the start. For convenience, it is connected with a button, and the entire device is powered by a toggle switch or a two-position button that has two fixed positions. In order to start such an electric motor, you need to connect everything through a button (tumbler) and hold the start button until it starts. When it starts, just release the button and the spring opens the contacts, turning off the starter
The specificity lies in the fact that asynchronous motors are originally intended to be connected to a network with three phases of 380 V or 220 V.
Important! In order to connect a single-phase electric motor to a single-phase network, you need to familiarize yourself with the motor data on the tag and know the following:
P \u003d 1.73 * 220 V * 2.0 * 0.67 \u003d 510 (W) calculation for 220 V
P \u003d 1.73 * 380 * 1.16 * 0.67 \u003d 510.9 (W) calculation for 380 V
According to the formula, it becomes clear that the electrical power exceeds the mechanical one. This is the necessary margin to compensate for power losses at the start - the creation of a rotating moment of the magnetic field.
There are two types of winding - star and delta. According to the information on the motor tag, you can determine which system is used in it.
The red arrows are the distribution of voltage in the motor windings, it indicates that a single phase voltage of 220 V is distributed on one winding, and a linear voltage of 380 V is distributed on the other two. Such a motor can be adapted to a single-phase network according to the recommendations on the tag: find out what voltage the windings are designed for, you can connect them with a star or a triangle.
It happens that a three-phase electric motor falls into the hands. It is from such engines that home-made circular saws, emery machines and various kinds of grinders are made. In general, a good owner knows what can be done with him. But the trouble is, a three-phase network in private homes is very rare, and it is not always possible to conduct it. But there are several ways to connect such a motor to a 220v network.
It should be understood that the engine power with such a connection, no matter how hard you try, will noticeably drop. So, the “triangle” connection uses only 70% of the engine power, and the “star” connection is even less - only 50%.
In this regard, the engine is desirable to have more powerful.
Important! When connecting the engine, be extremely careful. Do everything slowly. When changing the circuit, turn off the power supply and discharge the capacitor with an electric lamp. Do the work with at least two people.
So, in any connection scheme, capacitors are used. In fact, they play the role of the third phase. Thanks to him, the phase to which one terminal of the capacitor is connected shifts exactly as much as is necessary to simulate the third phase. Moreover, for the operation of the engine, one capacity (working) is used, and for starting, another one (starting) is used in parallel with the working one. Although this is not always necessary.
For example, for a lawn mower with a blade in the form of a sharpened blade, a 1 kW unit and only working capacitors will be enough, without the need for start-up tanks. This is due to the fact that the engine is idling at startup and it has enough energy to spin the shaft.
If you take a circular saw, hood or other device that gives the initial load on the shaft, then you can’t do without additional cans of capacitors to start. Someone may say: “why not connect the maximum capacity so that there is not enough?” But not everything is so simple. With this connection, the motor will overheat and may fail. Don't risk your equipment.
Important! Whatever the capacity of the capacitors, their operating voltage must be at least 400V, otherwise they will not work for a long time and may explode.
Three-phase motors come in both with three leads - for connecting only to a "star", and with six connections, with the choice of a star or delta circuit. The classic scheme can be seen in the figure. The figure on the left here shows a star connection. The photo on the right shows how it looks on a real motor brand.
It can be seen that for this it is necessary to install special jumpers on the desired outputs. These jumpers are included with the motor. In the case when there are only 3 outputs, then the star connection is already made inside the motor housing. In this case, it is simply impossible to change the connection scheme of the windings.
Some say that they did this so that the workers would not steal the units from home for their own needs. Be that as it may, such engine options can be successfully used for garage purposes, but their power will be noticeably lower than those connected by a triangle.
As you can see, the voltage of 220V is distributed into two series-connected windings, where each is designed for such a voltage. Therefore, power is lost almost twice, but such an engine can be used in many low-power devices.
The maximum power of a 380v motor in a 220v network can only be achieved using a delta connection. In addition to minimal power losses, the engine speed remains unchanged. Here, each winding is used for its operating voltage, hence the power. The connection diagram of such an electric motor is shown in Figure 1.
In Fig. 2, a brno is shown with a 6-pin terminal for the possibility of connecting with a triangle. The three resulting outputs are supplied: phase, zero and one output of the capacitor. The direction of rotation of the electric motor depends on where the second output of the capacitor is connected - phase or zero.
In the photo: an electric motor with only working capacitors without start-up tanks.
If there will be an initial load on the shaft, capacitors must be used to start. They are connected in parallel with the workers using a button or switch at the time of switching on. As soon as the engine reaches maximum speed, the start containers must be disconnected from the workers. If it's a button, just release it, and if it's a switch, then turn it off. Further, the engine uses only the working capacitors. Such a connection is shown in the photo.
The first thing to know is that capacitors must be non-polar, that is, not electrolytic. It is best to use brand containers - MBGO. They were successfully used in the USSR and in our time. They perfectly withstand voltage, current surges and the damaging effects of the environment.
They also have eyelets for mounting, helping to easily place them anywhere in the body of the device. Unfortunately, it is problematic to get them now, but there are many other modern capacitors that are no worse than the first ones. The main thing is that, as mentioned above, their operating voltage should not be less than 400V.
Calculation of capacitors. Capacitance of the working capacitor.
In order not to resort to long formulas and torture your brain, there is an easy way to calculate a capacitor for a 380v motor. For every 100 W (0.1 kW), 7 microfarads are taken. For example, if the engine is 1 kW, then we calculate as follows: 7 * 10 \u003d 70 microfarads. It is extremely difficult to find such a capacity in one bank, and it is also expensive. Therefore, most often the containers are connected in parallel, gaining the desired capacity.
This value is taken from the calculation of 2-3 times more than the capacity of the working capacitor. It should be borne in mind that this capacitance is taken in total with the working one, that is, for a 1 kW engine, the working one is equal to 70 microfarads, we multiply it by 2 or 3, and we get the required value. This is 70-140 microfarads of additional capacitance - starting. At the moment of switching on, it is connected to the working one and in total it turns out - 140-210 microfarads.
Capacitors, both working and starting, can be selected by the method from smaller to larger. So, having selected an average capacity, you can gradually add and monitor the engine's operating mode so that it does not overheat and has enough power on the shaft. Also, the starting capacitor is selected by adding until it starts smoothly without delay.
There are many varieties of electric motors, but for all the main characteristic is the mains voltage from which they operate and their power. We suggest considering how to connect an electric motor from 380 to 220 V in the star-delta way.
There are several types motor connections from 380 to 220:
Each of the methods has its own characteristics, advantages and disadvantages.
In many domestic electric motors, a star circuit has already been assembled, you only need to implement a triangle. In fact, you need to connect three phases and assemble a star from the remaining six ends of the winding. For a better understanding, see the star and delta drawing of the motor below. Here the ends are numbered from left to right, numbers 6, 4 and 5 are connected to three phases, as in the diagram:
Photo - Star and triangle of the electric motorIn a star connection with three leads, or as it is also called a star-triangle, the most important advantage is that the maximum power of the electric motor is generated. But at the same time, this compound is quite rarely used in production, much more often it can be found among amateur craftsmen. This is mainly because the circuit is very complex, and in powerful enterprises it simply does not make sense to organize such a laborious connection.
Photo - star connection In order for the circuit to work, you will need three starters. The diagram is shown in the drawing below.
Photo - star-triangle connection diagram To the first starter, which is designated K1, an electric current is connected on one side, and the stator winding is connected to the other. The free ends of the stator are connected to the starters K2 and K3. After that, the windings from the K2 starter are also connected to the remaining phases to form a triangle. When the K3 starter is turned on in the phase, the remaining ends are shortened a little and you get a star circuit.
Note that the third and second magnetic starters cannot be turned on at the same time. This can lead to a short circuit and an emergency shutdown of the electric motor machine. In order to avoid this, a kind of electric blocking is implemented. The principle of its operation is simple - when one starter turns on, the other turns off, i.e. blocking opens the circuit of its contacts.
The principle of operation of the circuit is relatively simple. When the first starter, designated K1, is connected to the network, the motor time relay also turns on the third starter K3. After the engine is started according to the star scheme and starts to work with more power than usual. After a certain time period, the time relay turns off the contacts of the third starter and turns on the second one. Now the engine is working in a delta pattern, reducing power slightly. When you need to turn off the power, the first starter circuit is turned on, during the next cycle the circuit is repeated.
Video: engine 380 to 220
In addition to the star-delta connection, there are also several more options that are used more often:
Complementing the paragraph about capacitors, it should be noted that it is necessary to select this component based on the minimum allowable capacity, gradually increasing it by trial methods to the optimal one required by the engine. If the electric motor is idle for a very long time, then it can simply burn out when connected to the network. Also remember that even after you have turned off the electric motors, capacitors store voltage at their contacts.
In no case do not touch them, but preferably protect them with a special insulating layer that will help avoid accidents. Also, before working with them, you need to do a discharge.
