Three-phase electric motors have a higher efficiency than single-phase 220 volts. If you have a 380 volt input in your house or garage, then be sure to buy a compressor or a machine with a three-phase electric motor. This will provide more stable and more economical operation of the devices. To start the motor, you do not need various starting devices and windings, because a rotating magnetic field appears in the stator immediately after connecting to the 380 volt mains.
The choice of the circuit for switching on the electric motor
Connection diagrams for 3-phase motors using magnetic starters I described in detail in previous articles: "" and "".
It is also possible to connect a three-phase motor to a 220 Volt network using capacitors according to. But there will be a significant drop in power and efficiency.
In the stator of an induction motor at 380 V, three separate windings are located, which are connected to each other in a triangle or star and 3 opposite phases are connected to three beams or peaks.
You must consider, that when connected with a star, the start will be smooth, but in order to achieve full power, it is necessary to connect the motor with a triangle. In this case, the power will increase by 1.5 times, but the current when starting powerful or medium-sized motors will be very high, and it can even damage the insulation of the windings.
Before connecting of the electric motor, read its characteristics in the passport and on the nameplate. This is especially important when connecting 3-phase electric motors of Western European production, which are designed to operate from a mains voltage of 400/690. An example of such a nameplate is in the picture below. Such motors are connected only according to the "triangle" scheme to our power grid. But many installers connect them in the same way as domestic ones in a "star" and electric motors burn out at the same time, especially quickly under load.
On practice all electric motors of domestic production 380 volts are connected with a star. An example in the picture. 
In very rare cases in production, in order to squeeze out all the power, a combined star-delta circuit is used. You will learn more about this at the very end of the article.
Star-delta motor connection diagram
In some of our electric motors only 3 the end of the stator with windings - this means that a star is already assembled inside the motor. You just need to connect 3 phases to them. And in order to collect a star, both ends are needed, each winding or 6 leads.
The numbering of the ends of the windings on the diagrams goes from left to right. Numbers 4, 5 and 6 are connected to 3 phases A-B-C from the mains. 
When a three-phase electric motor is connected by a star, the beginning of its stator windings are connected together at one point, and 3 phases of 380 volt power supply are connected to the ends of the windings.
When connected by a triangle the stator windings are connected in series with each other. In practice, it is necessary to connect the end of one winding to the beginning of the next. Three power phases are connected to three points of their connection.
Star-delta connection
To connect the motor according to a rather rare star pattern at start-up, with subsequent transfer to work in an operating mode in a triangle circuit. So We will be able to squeeze out the maximum power, but we get a rather complex scheme without the possibility of reversing or changing the direction of rotation. 
For the circuit to work, 3 starters are required. The first K1 is connected to the power supply on one side, and on the other, the ends of the stator windings. They are also connected to K2 and K3. From the K2 starter, the beginning of the windings are connected, respectively, to other phases according to the delta scheme. When K3 is turned on, all 3 phases are short-circuited with each other and a star operation scheme is obtained.
Attention, magnetic starters K2 and K3 should not be turned on at the same time, otherwise an emergency shutdown of the circuit breaker will occur due to the occurrence of an interphase short circuit. Therefore, an electrical interlock is made between them - when one of them is turned on, the block is opened by contacts, the control circuit of the other.
The scheme works as follows. When the K1 starter is turned on, the time relay turns on K3 and the engine starts up according to the star scheme. After a predetermined interval, sufficient for a complete engine start, the time relay turns off the K3 starter and turns on K2. The motor switches to the work of the windings according to the triangle pattern.
Disconnection occurs starter K1. When you restart it, everything is repeated again.
Related materials:
Experienced Electrician:
Roman, hello. To do this, you need to read the instructions or ask questions from the manufacturer of the inverter, namely, whether the inverter is capable of connecting to the load (or in other words, its overload capacity for a short time). If you do not risk it, then it is easier (when 220 volts disappears), turn off the electric motor with an automatic switch or a switch, turn on the power from the inverter with a changeover switch (thus powering the frequency converter) and then turn on the engine. Or make a scheme of uninterrupted operation - on an ongoing basis, supply the mains voltage to the inverter, and take it from the inverter to the frequency converter. In the event of a power outage, the inverter remains in operation thanks to the battery and there is no interruption in the power supply.
Sergey:
Good afternoon. A single-phase motor from an old, Soviet washing machine rotates in different directions every time it starts (no system). The engine has 4 leads (2 thick, 2 thin. I connected it through a switch with a third outgoing contact. After starting, the engine runs stably (does not heat up). I can’t understand why there is rotation in different directions.
Experienced Electrician:
Sergey, hello. The thing is that a single-phase motor does not matter where to rotate. The field is not circular (as in a three-phase network), but pulsating 1/50 of a second on the plus phase relative to zero, and 1/50 is “minus”. It's like turning the battery a hundred times a second. Only after the engine has spun does it keep its rotation. In the old washing machine, a strict direction of rotation may not have been provided. If we assume this, then at the moment of launch on the "positive" half-wave of the sinusoid, it is launched in one direction, with a negative half-wave - in the other. It makes sense to try to set the offset of the starting winding current through the capacitor. The current in the starting winding will begin to lead the voltage and will set the rotation vector. As I understand it, you now have two wires (phase and zero) going to the motor from the working winding. One of the wires of the starting winding is combined with the phase (conditionally, just actually tightly with one of the wires), and the second wire goes to zero through the third non-fixing contact (also conditionally, in fact, to the other of the network wires). So try to install a capacitor with a capacity of 5 to 20 μF between the wire and the non-flashing contact and observe the result. In theory, you should rigidly set the direction of the magnetic field by this. In fact, this is a capacitor motor (single-phase asynchronous all capacitor ones) and only three points are possible here: either the capacitor always works and then the capacitance must be selected, or it sets the rotation, or the start occurs without it, but in any direction.
Galina:
Hello
Sergey:
Good afternoon. I assembled the circuit, as you said, set the capacitor to 10 microfarads, the engine starts steadily now only in one direction. Change the direction of rotation only if the ends of the starting winding are reversed. So the theory worked flawlessly in practice. Thank you very much for your advice.
Galina:
Thank you for your answer, I bought a cnc milling machine in China, a 3-phase 220 motor, and we (I live in Argentina) have a single-phase 220 network, or a 3-phase 380
I consulted with local experts - they say that it is necessary to change the engine, but I really do not want to. Help with advice on how to connect the machine.Galina:
Hello! Thank you so much for the information! In a couple of days the machine comes in. I'll see what's really there, and not just on paper, and I suppose I will have more questions for you. Thanks again!
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Hello! Is this option possible: draw a line of 3 phases of 380 v and put a step-down transformer in order to have 3 phases of 220v? The machine has 4 motors, with a main power of 5.5 kW. If this is possible, what kind of tr-r is needed?
Yura:
Hello!
Can you please tell me - is it possible to power an asynchronous three-phase electric motor 3.5 kW from 12-volt batteries? For example, using three household inverters 12-220 with a pure sine wave.Experienced Electrician:
Yuri, hello. Purely theoretically, this is possible, but in practice you will face the fact that when starting the induction motor creates a large starting current and you will have to take the appropriate inverter. The second point is full phasing (frequency shift for three inverters at an angle of 120 ° relative to each other), which cannot be done if this is not provided by the manufacturer, therefore you cannot achieve manual synchronization at a frequency of 50 Hz (50 times per second). Plus, the engine power is quite large. Based on this, I would recommend that you pay attention to the combination "battery-inverter-frequency converter". The frequency converter is capable of delivering the required synchronized phases of the voltage that will be at the input. Almost all motors can be switched on at 220 and 380 volts. Therefore, having received the required voltage and having obtained the required connection scheme, it is possible to make a smooth start with the help of a frequency converter, avoiding large inrush currents.
Yura:
I didn't understand a little - I have 1.5 kW inverters, that is, do you advise using a battery of accumulators and one such inverter in conjunction with a frequency converter? and how will he pull out ???
Or do you advise using an inverter of the corresponding power - 3.5 kW? then the need for a frequency converter is not clear ...Experienced Electrician:
I will try to explain.
1. Review the information on three-phase current. Three phases are not three voltages at 220 volts. Each phase has a frequency of 50 hertz, that is, 100 times per second it changes its value from plus to minus. In order for an induction motor to start working, it needs a circular field. In this field, the three phases are shifted relative to each other by an angle of 120 °. In other words, phase A reaches its peak, after 1/3 of the time this peak reaches phase B, after 2/3 of the time phase C, then the process is repeated. If the change in the peaks of the sinusoid is chaotic, the motor will not start rotating, it will just hum. Therefore, either your inverters must be phased or they don't make sense.
2. Study the information on induction motors. The starting current reaches 3-8 times the rated current. Therefore, if we take an approximate value of 5 amperes, then when the engine starts, the current can be 15-40 amperes or 3.3 - 8.8 kW per phase. An inverter of lower power will burn out immediately, which means you need to take the inverter at its maximum power, even if it only lasts half a second or even less, and this will be an expensive pleasure.
3. Study the information on the frequency converter. The frequency converter can provide both a smooth start and a conversion of one phase into three. A smooth start will allow you to avoid large inrush currents (and the purchase of a super-powerful inverter), and converting one phase into three will avoid the expensive procedure for phasing the inverters (if they are not initially adapted to this, then on your own you will definitely not be able to do this and you will have to find a good electronics engineer ).I advise you to take a powerful inverter in conjunction with a frequency converter if you really need to get the full power from your motor.
Valery:
Thank you very much for everything. For patience, re-clarification of everything that has been repeated many times in other comments. I reread all this, in places more than once. I read a lot inf. on different sites for the translation of 3 f.dvig. to the 220v network. (from the moment when the assistants set fire to the electric motor of a self-made small machine). But I learned much more from you, such features that I did not know about and did not meet before. Today, after a search engine, I went to this site, re-read almost all the comments and was amazed at the usefulness and availability of information.
About my questions. Here's the thing. On my old machine (former, father's) there is the same old email. dv. But he lost power, "beats" from the body (probably, the burned-out winding is shorting). There is no tag, a classic triangle, no cleats - it was once altered, probably. I am offered a new capacity, Polish, it seems, with the given options on the tag. By the way, there is 50 Hz for each option. And after sending a comment, I carefully looked at all 4 given options and understood why the current in the triangle is higher.
I will take it, turn it on in 220 according to option 1 in a triangle through capacitors with 70% power. The gear ratio can be increased, but the power for the machine could be higher.
Yes, besides the classic triangle and star, there are other options for connecting 380 to the 220 network. And there is (you know) an easier way to determine the beginning of the windings using a battery and a switchman.Valery:
Today I received a photo of the nameplate email. dv. You're right. There are 3 and 4 options 60Hz. And now it is clear that it could not be otherwise and that at 50Hz - a maximum of 3000 rpm. Another question. How reliably and continuously with one turn-on electrolytic capacitors work through a powerful diode as a working one. cond.?
Alexander:
Hello, tell me, how to attach a file with a photo to ask a question?
Sergey:
Good afternoon.
A bit of history. On a hot water boiler (industrial large - for heating the enterprise) I use two VILO circulation pumps with a German 7.5 kW electric motor each. Upon receipt of both pumps, we connected them with a "triangle". We worked for a week (everything was fine). The adjusters of the boiler automation came and told us that the connection diagram for both motors should be switched to the "star". We worked for a week and one by one both engines burned out. Tell me, can the reconnection from triangle to star cause burned out German engines? Thanks.Alexander:
Hello Experienced Electrician) Tell me your opinion about such a circuit for connecting motors, came across it on one forum
"Incomplete star opposite, with working capacitors in two windings"
Link to a diagram and a diagram describing the principle of operation of such a scheme - https://1drv.ms/f/s!AsqtKLfAMo-VgzgHOledCBOrSua9It is said that such a motor connection diagram was developed for a two-phase network and shows the best results when connected to 2 phases. But in a single-phase 220v network, it is used because it has better characteristics than the classic ones: a star and a triangle.
What can you say about this option for connecting a three-phase motor to a 220v network. Has the right to life? I want to try it on a homemade lawn mower.Experienced Electrician:
Alexander, hello. What can I tell you? First, the literacy of both the presentation of the material and the literacy of the language of the article are incredibly strong. Secondly, for some reason, very few people know about this method. Thirdly, if this method were effective and the best, it would have long been included in the educational literature. Fourthly, nowhere is there a theoretical calculation of this method. Fifth, there are proportions, but there are no formulas for calculating the capacitance (that is, conventionally, you can take 1000 μF or 0.1 μF as the reference point - the main thing is to observe the proportions ???). Sixth, the topic was not written by an electrician. Seventh, I personally do not fit in my head the first winding, which is turned on backwards and through a capacitor - all this suggests that someone invented something and wants to pass off something as an invention that supposedly works better for a two-phase networks. Theoretically, this can be allowed, but there is little theoretical data for reflection. In theory, if somehow one or the other half-wave is received from one or the other phase, but the circuit should then have a different form (when using two phases, this is definitely a star, but using a neutral wire and two capacitors to it or from In general, experiment, and then unsubscribe - I wonder what happens, but personally, I don’t want to carry out such experiments, well, or if they give me an engine and say - you can kill it, then I will experiment. Regarding the selection of capacitors, I have already written in the comments and in the links to the article "Capacitor for a three-phase motor" on this site and on the site of the "hereditary master" - it is not necessary to mindlessly put a capacitor according to the formula. current in a specific cycle of work.
Alexander:
Thanks for the answer.
On the forum where I came across this, several people tried this circuit on their engines (including the person who posted it), they say that they are very satisfied with the results of its work. Regarding the competence of the person who suggested it, as I understand it, he seems to be in the topic (and the moderator of that forum), the scheme is not his, as he said he himself found it in some old books on engines. But then, I have an engine suitable for experiments , I'll try on it.
Regarding the formulas, I just did not present all the entries from that branch, there is a lot of things written there, I also added from the main one if you are interested, take a look at the same link.Experienced Electrician:
Alexander, experiment and write the result. I can say one thing - I am an inquisitive comrade, but I have never heard of such a scheme either from textbooks or from the lips of many authoritative senior comrades. My neighbor, an even more inquisitive electronics engineer with a bias in electricity, has not heard either. One of these days I will try to ask him.
Competence is so ... questionable when it comes to the Internet. You never know who is sitting on the other side of the screen and what he is, and whether the diploma he is talking about is hanging on his wall, and whether he knows any of the subjects that are indicated in the diploma. I'm not trying to charm the person at all, I'm just trying to say that you don't always have to believe one hundred percent of the person on the other side of the screen. If something happens, you cannot press him against the wall for bad advice, and this gives rise to complete irresponsibility.
There is one more "black" moment - forums are often created in order to generate income and all means are good for this, as an option, suggest some tricky topic, promote it, even if it is not quite working, but unique, that is, only on his website. And "several" people, it can be just a moderator, under several nicknames to talk to himself to promote the topic. Again, I don’t hay that particular person, but I’ve already met such a black PR forum.
Now let's touch on old books and the Soviet Union. In the USSR, there were few fools (among those who were engaged in development), and if the scheme had proven itself, it would probably have been included in the textbooks I studied, at least for mentioning and for general development that such an option is possible. Yes, and our teachers were not fools, and on electric cars, the uncle generally gave a lot of interesting information beyond the curriculum, but he had not heard of this scheme either.
Conclusion, I do not believe that this circuit is better (perhaps for two phases or better, but it is still necessary to look at it and draw a "correct" circuit to understand the action of currents and their displacement), although I admit that it works. There are a lot of such options when someone has thought of something, but it works - as a rule, a person himself does not understand what he has done and does not delve into the essence, but is trying hard to modernize something.
Well, and one more conclusion: if this scheme were really better, then it would be at least known, but I only learned about it from you with all my irrepressible curiosity.
In general, I expect your opinions and results, and then you look and I myself will conduct an experiment with a neighbor already on a practical and theoretical basis.
Alexander:
Good day to all. I can now, as I promised, tell about the experiments when connecting my AOL engine according to the circuit found on one forum - the so-called
"Incomplete star, oncoming" In general, I made the mower itself and installed the engine on it. I calculated the capacitors according to the formulas that were given in the description of the circuit, which were not there - I bought it on the market, it turned out that it was not so easy to find high-voltage ones at 600V or higher. I assembled everything according to the given scheme, but the scheme was not unpretentious! (for me, compared to a triangle) I double-checked everything. It turned out that the engine with knives quickly started up only when another 30mkF was added to the calculated starting capacitors (it was a bit tough on the calculated ones). I turned the engine idle in the workshop for half an hour and watched the heating - everything turned out to be good, the engine almost did not warm up. I liked the engine idling very much, the sound and visual of the engine seemed to work like a 380V family (I checked it at work from 380v) I left to mow the next day in the morning. In general, I mowed for more than an hour, tall grass (to give a load) - the result is excellent, the engine warms up, but you can quite hold your hand (considering that it was +25 outside,) A couple of times the engine "stalled" in tall grass, but it has only 0 , 4 kW. The working capacitors in the second circuit warmed up a little (added 1.5 microfarads to the calculated ones), the rest were cold. Then he mowed two more times - the engine worked "like a clock", in general, I was satisfied with the result of connecting the engine, only the engine would be a little more powerful, (0.8 kW) would be generally beautiful) The capacitors were eventually set as follows:
Launchers = 100mkF at 300v.
Working 1 winding = 4.8 microfarads at 600v.
Working 2 winding = 9.5 microfarads at 600v.
This works on my engine. It is interesting to try such a connection on an engine more powerful than 1.5-2 kW.Alexander:
Hello. You are right) I immediately connected it with a triangle in the workshop, though I didn’t mow on it, and I can only evaluate the engine's work visually, by ear and by my feelings) since I have nothing to measure the same currents on different circuits. I am far from a serious electrician, I can basically twist something in a heap according to a ready-made scheme with already known details, ring and check a 220-380 voltmeter). In the description of the circuit, it was said that its advantage is in lower losses of engine power and in its operating mode close to the nominal. I will say that on a triangle it was easier for me to brake the shaft on the engine than on this diagram. Yes, and he rotated on it, I would say faster. It works for me on this engine and I liked how the engine itself works, so I did not collect and shove two circuits in turn into one box and check how it mows. So far, I pushed the capacitors into a temporary box to see how it will work (maybe something else will have to be added or removed), and then I thought the whole thing would be beautifully and compactly arranged with some kind of protection. I'm wondering where I stumbled upon this circuit, people used it to connect low-power motors and no one wrote about connecting at least 1.5 or 2 kW. For them, as I understand it, you need a lot (in comparison with the triangle) capacitors, and even for high voltage there should be. I was here and decided to ask around about this scheme, since I really had never heard of it before and thought maybe the specialists would say from the point of view of theory and science whether it should work or not.
I can say for sure that the engine is spinning and, as for me, it’s very good, but what should be there with currents, voltages and what should be lagging or ahead of it according to this scheme and I would like to hear from someone who knows. Maybe this schematic is just a scam? and it is no different from the same triangle (except for extra wires and capacitors. At home now I no longer need powerful motors to try to connect them through capacitors according to this scheme and see how they would work. , so they have motors of about 2.5 kW connected in a triangle, if you put a little more load on them, as if they had no more than a kilowatt in them. Now it's just that there is all this in the workshop, which has 380. if everything is "gut" I will arrange my miracle mower correctly and post a photo, maybe someone will come in handy.Vladimir:
Good evening, tell me how to change the direction of rotation of the shaft of a 380V synchronous electric motor connected from a star to a triangle.
I tried another option. Star connection. I start the 3 kilowatt engine with a 160 microfarad capacitor. And then I remove it from the network (if not removed from the network, the capacitor starts to warm up). And the engine runs independently at pretty good speed. is it possible to use it in this way? is it not dangerous?
novel:
Hello! There is a 1.5 kW Vesper frequency converter, which transforms from one phase of a 220 volt network into 3 phases at the output with an interphase 220V to supply an asynchronous 1.1 kW. dv. 1500 rpm However, when the 220 volt network is disconnected, it is necessary to power it from a direct current inverter, which uses a battery as a backup power source. The question is, is it possible to do this through the ABB rocker switch (i.e. switch manually to Vesper's power supply from the direct current inverter) and will the direct current inverter not be damaged?
Valery:
Hello. Can you please tell me if this motor (imported) can be used to connect to our 220V network for a woodworking machine?
There are 4 options on the nameplate:
- 230, triangle, 1.5kw, 2820 / min., 5.7А, 81.3%
- 400, star, 1.5kw, 2800 / min., 3.3A, 81.3%
- 265, triangle, 1.74kw, 3380 / min, 5.7A, 84%
- 460, evezda, 1.74kw, 3380 / min, 3.3A, 84%
Judging by this, this engine is very well suited for do.o. machine (according to the 1st option). Probably there are 6 contacts in the box? Good (relatively) turnover. Confuses 230V - how will it behave in a 220V network? Why is the maximum current according to option 1, 3?
Can this motor be used for a d / o machine and how to connect to a 220V network?
Today, asynchronous electric motors are popular due to their reliability, excellent performance and relatively low cost. Motors of this type are designed to withstand high mechanical stress. In order for the unit to start up successfully, it must be connected correctly. For this, connections of the "star" and "triangle" type, as well as their combination, are used.
Connection types
The design of an electric motor is quite simple and consists of two main elements - a stationary stator and an internally rotating rotor... Each of these parts has its own current-carrying windings. The stator is laid in special grooves with the obligatory observance of a distance of 120 degrees.
The principle of operation of the motor is simple - after turning on the starter and applying voltage to the stator, a magnetic field arises, forcing the rotor to rotate. Both ends of the windings are led out into a junction box and are arranged in two rows. Their conclusions are marked with the letter "C" and receive a digital designation in the range from 1 to 6.
To connect them, you can use one of three ways:
- "Star";
- "Triangle";
- "Star-triangle".
However, the combined circuit cannot be used if it is necessary to reduce the starting current, but at the same time a large torque is required. In this case, an electric motor with a wound rotor, equipped with a rheostat, should be used.
If we talk about the advantages of combining the two connection methods, then two can be noted:
- Thanks to the soft start, the service life is increased.
- It is possible to create two power levels for the unit.
Today, the most widely used electric motors are designed to operate in 220 and 380 volt networks. It is on this that the choice of the connection scheme depends. Thus, it is recommended to use the "triangle" at a voltage of 220 V, and the "star" at 380 V.
Since they have high reliability, the simplicity of the design allows to increase the engine resource. With collector motors, from the point of view of connecting to the network, things are easier - no additional devices are needed to start. Asynchronous devices need a capacitor bank or a frequency converter if they need to be connected to a 220 V.
How the motor is connected to a three-phase 380 V network
In three-phase asynchronous motors, there are three identical windings, they are connected according to a certain scheme. There are only two schemes for connecting the windings of electric motors:
- Star.
- Triangle.
By connecting the windings according to the "delta" scheme, maximum power can be achieved. But at the start-up stage, large currents arise, they are dangerous for technology.
If connected according to the "star" scheme, the motor will start smoothly, since the currents are low. True, with such a connection, it will not work to achieve high power. If you pay attention to these points, it will become clear why electric motors, when connected to a 220 V household network, are connected only according to the "star" scheme. If you choose the "triangle" scheme, then the likelihood of failure of the electric motor increases.
In some cases, when it is required to achieve a large power rating from the drive, a combined connection is used. The launch is carried out when the windings are connected to the "star", and then the transition to the "triangle" is carried out.
Star and triangle
Regardless of which one you choose 380 to 220 V, you need to know the design features of the motor. Please note that:
- There are three stator windings, each with two leads - the beginning and the end. They are led out into the terminal box. With the help of jumpers, the terminals of the windings are connected according to the "star" or "delta" schemes.
- There are three phases in the 380 V network, which are designated by the letters A, B and C.
In order to make a connection according to the "star" scheme, you need to close all the beginning of the windings together.
And the ends are powered by 380 V. You need to know this when connecting an electric motor 380 to 220 volts. To connect the windings according to the "delta" scheme, it is necessary to close the beginning of the coil with the end of the adjacent one. It turns out that you connect all the windings in series, a kind of triangle is formed, to the tops of which the power is connected.
Transient switching circuit
In order to smoothly start a three-phase electric motor and get maximum power, it is necessary to turn it on according to the "star" scheme. As soon as the rotor reaches the rated speed, commutation is performed and the transition to switching on according to the "delta" scheme. But such a transitional scheme has a significant drawback - it cannot be reversed.
When using a transient circuit, three magnetic starters are used for:
- The first one makes the connection of the initial ends of the stator windings and the supply phases.
- A second starter is required for delta connection. With its help, the ends of the stator windings are connected.
- With the help of the third starter, the ends of the windings are connected to the mains.
In this case, the second and third starters cannot be put into operation at the same time, as a short circuit will appear. Consequently, the circuit breaker installed in the panel will cut off the power supply. To prevent the simultaneous activation of two starters, an electrical interlock is used. In this case, it is possible to turn on only one starter.
How the transient circuit works
The peculiarity of the functioning of the transient circuit:
- The first magnetic starter is turned on.
- A time relay is started, which allows the third magnetic starter to be put into operation (the engine is started with windings connected according to the "star" scheme).
- After the time specified in the relay settings, the third one is disconnected and the second starter is put into operation. In this case, the windings are connected in a "delta" circuit.
In order to stop working, you need to open the power contacts of the first starter.
Features of connection to a single-phase network
When used, it will not be possible to achieve maximum power. In order to connect an electric motor 380 to 220 with a capacitor, you need to adhere to several rules. And the most important thing is to correctly select the capacitance of the capacitors. True, in this case, the motor power will not exceed 50% of the maximum.
Please note that when the electric motor is switched on to the 220 V network, even when the windings are connected according to the "triangle" scheme, the currents will not reach the critical value. Therefore, it is allowed to use this scheme, even more - it is considered optimal when working in this mode.
Connection diagram to the 220 V network
If power is supplied from the 380 network, then a separate phase is connected to each winding. Moreover, the three phases are shifted relative to each other by 120 degrees. But in the case of connecting to a 220 V network, it turns out that there is only one phase. True, the second is zero. But with the help of a capacitor, a third is made - a shift is made by 120 degrees relative to the first two.
Please note that a motor designed to be connected to a 380 V network is easiest to connect to 220 V using capacitors only. There are two more ways - using a frequency converter or one more. But these methods increase either the cost of the entire drive or its dimensions.
Working and starting capacitors
When starting an electric motor with a power below 1.5 kW (provided that at the initial stage there is no load on the rotor), only a working capacitor is allowed. Connecting an electric motor 380 to 220 without a starting capacitor is possible only under this condition. And if the rotor is affected by a load and the motor power is more than 1.5 kW, it is necessary to use a starting capacitor, which must be turned on for a few seconds.
The working capacitor is connected to the zero terminal and to the third vertex of the triangle. If it is necessary to reverse the rotor, then you just need to connect the output of the capacitor to the phase, and not to zero. The starting capacitor is switched on using a button without a lock parallel to the operating one. He participates in the work until the acceleration of the electric motor occurs.
To select a working capacitor when turning on the windings according to the "triangle" scheme, you need to use the following formula:
The starting capacitor is selected empirically. Its capacity should be about 2-3 times that of a worker.
The asynchronous motor is powered from a three-phase AC network. Such a motor, with a simple wiring diagram, is equipped with three windings located on the stator. Each winding is offset from each other by an angle of 120 degrees. Shifting this angle is designed to create a rotation of the magnetic field.
The ends of the phase windings of the electric motor are brought out to a special "block". This is done for the sake of ease of connection. In electrical engineering, the main 2 methods of connecting asynchronous electric motors are used: the "triangle" method and the "star" method. When connecting the ends, use jumpers specially designed for this.
Differences between "star" and "triangle"
Based on the theory and practical knowledge of the basics of electrical engineering, the "star" connection method allows the electric motor to run smoother and softer. But at the same time, this method does not allow the engine to reach all the power presented in the technical specifications.
By connecting the phase windings according to the "delta" scheme, the motor is able to quickly reach its maximum operating power. This allows you to use the full efficiency of the electric motor, according to the data sheet. But this connection scheme has its drawback: high starting currents. To reduce the value of the currents, a starting rheostat is used, allowing a smoother engine start.
Star connection and its benefits
Each of the three working windings of the electric motor has two terminals - the beginning and the end, respectively. The ends of all three windings are connected to one common point, the so-called neutral.
If there is a neutral wire in the circuit, the circuit is called 4-wire, otherwise it will be considered 3-wire.
The beginning of the terminals is connected to the corresponding phases of the supply network. The applied voltage on such phases is 380 V, less often 660 V.
The main advantages of using the "star" scheme:
- Stable and long-term mode of non-stop engine operation;
- Increased reliability and durability due to reduced equipment power;
- Maximum smoothness of starting the electric drive;
- Possibility of exposure to short-term overload;
- During operation, the equipment case does not overheat.
There is equipment with internal connection of the ends of the windings. Only three pins will be connected to the block of such equipment, which does not allow using other connection methods. Electrical equipment made in this form does not require competent specialists for its connection.
Delta connection and its benefits
The principle of the "triangle" connection is to connect in series the end of the winding of phase A with the beginning of the winding of phase B. And then, by analogy, the end of one winding with the beginning of the other. As a result, the end of the phase C winding closes the electrical circuit, creating a continuous loop. This scheme could be called a circle, if not for the mount structure. The triangle shape is given by the ergonomic arrangement of the winding connection.
When connected with a "triangle" on each of the windings, there is a line voltage equal to 220V or 380V.
The main advantages of using the "triangle" scheme:
- Increase to the maximum value of the power of electrical equipment;
- Using a starting rheostat;
- Increased torque;
- High tractive effort.
Disadvantages:
- Increased starting current;
- The engine gets very hot during prolonged operation.
The method of connecting motor windings "delta" is widely used when working with powerful mechanisms and the presence of high starting loads. A large torque is created by increasing the self-induction EMF indicators caused by large currents flowing.
Star-delta connection type
In complex mechanisms, a combined "star-delta" scheme is often used. With such a switch, the power rises sharply, and if the engine is not designed to operate according to the "triangle" method according to its technical characteristics, then it will overheat and burn out.
Motors with increased power have high starting currents, and as a result, when starting, they often cause blown fuses, shutdown of automatic machines. To reduce the line voltage in the stator windings, autotransformers, universal chokes, starting rheostats or a "star" connection are used.
In this case, the voltage at the connection of each winding will be 1.73 times less, therefore, the current flowing during this period will also be less. Further, the frequency increases and the current reading continues to decrease. Then, using a relay-contact circuit, there will be a switching from "star" to "delta".
As a result, using this combination, we get maximum reliability and effective productivity of the used electrical equipment, without fear of disabling it.
Star-delta switching is permissible for light duty motors. This method is not applicable if it is necessary to reduce the starting current and at the same time not to reduce the large starting torque. In this case, a phase-wound rotor motor with a starting rheostat is used.
The main advantages of the combination:
- Increased service life. Smooth start-up allows you to avoid uneven load on the mechanical part of the installation;
- Possibility of creating two power levels.
- At the moment of starting the electric motor, its starting current is 7 times the operating current.
- 1.5 times more power when connected windings by the "triangle" method.
- For smooth starting and motor overload protection, frequency wires are often used.
- When using the star connection method, pay special attention to the absence of "phase imbalance", otherwise the equipment may fail.
- Linear and phase voltages at delta connection- are equal to each other, as are the linear and phase currents in the "star" connection.
- To connect the engine to a household network, they often use phase-shifting capacitor.
Switching the motor from star to delta is used to protect electrical circuits from overloads. Basically, powerful three-phase asynchronous motors from 30-50 kW are switched from star to delta, and high-speed ~ 3000 rpm, sometimes 1500 rpm.
It is known that at the moment of starting the electric motor, its current increases up to 7 times. A squirrel cage induction motor resembles a transformer with a short-circuited secondary winding.
If the motor is connected to a star, then a voltage of 220 volts is supplied to each of its windings, and if the motor is connected to a triangle, then a voltage of 380 volts falls on each of its windings. Here Ohm's law "I = U / R" comes into play, the higher the voltage, the higher the current, and the resistance does not change.
Simply put, when connected to a delta (380), the current will be higher than when connected to a star (220).
When the electric motor accelerates and picks up full speed, the picture changes completely. The fact is that the engine has a power that does not depend on whether it is connected to a star or a delta. Motor power depends to a large extent on iron and wire cross-section. Here another law of electrical engineering "W = I * U"
Power is equal to the current multiplied by the voltage, that is, the higher the voltage, the lower the current. When connected to a delta (380), the current will be lower than to a star (220).
Let's go to practice
In the motor, the ends of the windings are brought out to the "terminal block" in such a way that, depending on how the jumpers are placed, a star or delta connection will be obtained, as shown in the figure. Such a diagram is usually drawn on the lid.
In order to switch from star to delta, we will use the contacts of magnetic starters instead of jumpers.
Consider the power section circuit, shown in bold lines.
Comments and Feedback
Star-Triangle: 133 comments
- Grumm
Triangle error!
But that's okay ...
How is phasing carried out (configured)? - Electrician
The content of the article is not true.
When the motor is switched from star to delta, the supply voltage will accordingly change from 380/220 to 220/127.
The motor switched on with a triangle is switched on to a voltage of 220/127 V.
If you turn it on at 380/220, it will burn out.- Roman
This is the 380/660 Y / A engine. You are not right.
- Roman
Confused - correct: 380/660 A / Y
- Roman
- Roman
- admin Post author
According to the scheme, the motor will rotate in one direction, if you swap the phases on the P1 starter, then the rotation of the motor will change. The most important thing in this circuit is not to confuse the connection of the P2 magnetic starter, its contacts perform the functions of JUMPERS for connecting to the TRIANGLE.
- admin Post author
The content of the article is quite true. When the motor is connected to a triangle, a voltage of 380 volts is supplied to each winding, and if at the same time the motor is connected to a star, then a voltage of 220 volts is supplied to each winding. According to the scheme, we temporarily supply a reduced voltage of 220V for 10-15 seconds in order to reduce the starting current and reduce the jerk of the engine at the time of starting. The engine then switches to normal operation.
- admin Post author
Yes, it is worth pointing out that the voltage of the motor must correspond to the voltage of the mains, at this voltage it must work connected in a delta.
By the way, I spied on this scheme on Japanese equipment.
- admin Post author
Electrician, where did you get the 220/127 from. If the mains voltage is 380/220, then this means when the motor is included in the triangle, each of its windings operates at 380 volts, and when the motor is included in the star, then 220 volts are supplied to the windings.
- Evgeniy
Guys, a similar scheme is already being used in practice. It is called "warm start" in pumping
stations, etc. in high-rise construction.- Evgeniy
Excuse me, what start? warm? Why not hot? This method of starting is called "combined" in pumping stations. There is a "direct" start (star or triangle).
However, more often nowadays it is found in high-rise construction (when using household power stations, water supply, and this is important) frequency or frequency-network start-up.
Now about the subject. This star-delta start provides smoother acceleration on powerful motors to minimize line drawdown.
However, as everyone knows, with a star we have a “shortage” in power.
Not fatal on transition. Maximum power on the triangle. By the way, this method is used when using powerful pumps of fire extinguishing stations.
The only thing that does not correspond to reality (practice) in the circuit is the connection in the terminal box of the motor
spruce.
An example is Grundfoss pumps. The connection is very simple - U1-W2. V1-U2. W1-V2- Alexander
Not a shortage in power, but in torque. The motor torque depends on the square of the voltage and when it is connected to the triangle, the torque is almost 3 times higher. A star circuit when starting the engine is used to reduce starting currents.
- Alexander
- Evgeniy
- Dmitriy
The circuit is absolutely correct and everything is described correctly.
- Megavolt
Nobody noticed that the PT and P3 relays are connected bypassing the "Start" button?
They will work as soon as you plug the circuit into the network. - admin Post author
Megavolt, you are right thanks for the comment. They must be connected on the other side of the start button or through an additional normally open contact P1
- admin Post author
The circuit has been fixed. If you click on the diagram, you can see the old diagram.
Diagram B at the top with dashed lines on the left shows the possibility of connecting the coils of the starter and the time relay for 220 and 380 Volts. This common wire is connected to the 380 volt phase, or to zero 220V. Simultaneously connect on the dotted line and to the phase and to zero is not desirable, it may turn out to be a "shorty".
- Michael
Thanks for the diagram. Please, if possible, give a diagram when the starter coils are designed for different voltages For example P2 for 220V and P3 for 380V The STOP button in this case for some reason does not work Thank you.
- admin Post author
If the coils of starters are for different voltages, then instead of connecting to a common wire, the 220V coils are connected to zero, and the 380V coils are connected to the phase. The rest of the scheme is unchanged.
- Michael
The Stop button does not work in this case. Installed a two-contact Stop button. I break two phases.
- admin Post author
And this button opens exactly two phases. We have two-pin buttons, one contact opens the circuit, the other closes, turning on the signal lights.
How it doesn't work, doesn't turn it on or off. - Impedance
I thank admina for a short, correct explanation of the principle of operation of this scheme !!!
- Bach
There are starters together with a time relay. Remove easily connect
- Evgeniy
- admin Post author
Eugene, Ohm's law is valid for active load.
Ohm's law is preserved, only on a rotating motor, in addition to the active resistance of the windings, inductive resistance appears. And the inductive load with increasing voltage increases the inductive resistance, respectively, the current decreasesYes, for reliable operation of the circuit, you should take the 660/380 motor if the voltage in the network is 380/220
- Pamir
Why was no one embarrassed by the statement that “When connected to a triangle (380), the current will be lower than to a star (220)”, which directly contradicts what was written a few paragraphs above.
With what fright, one wonders, the powers in the star and in the triangle are equal, then it makes sense to switch to the triangle if the engine runs at rated power in the star as well?
admin, inductive (reactance) resistance depends only on frequency and not on voltage. And Ohm's law also works in this case, the higher the voltage, the higher the current. - admin Post author
The circuit reduces the starting current, the motor turns on, for a short time, for the time of starting into a star. The jerk that the engine makes when starting is also reduced, especially if the engine is under load.
And in the triangle, less current, more power, when the engine is running.The power of the motor does not depend on whether the motor is included in a star or a delta. Engine power depends to a greater extent on the load
- Pamir
The power that the engine can develop is written on the nameplate, and it is determined by the parameters of the engine and the connection method, and only the current consumed power depends on the load and it cannot exceed the declared one.
When connected to a star, a lower voltage is applied to the motor windings (not linear 380 but phase 220), respectively, a lower starting and operating current (Ohm's law). Hence, it is clear that in a star the power that the engine is capable of developing will be less than the nominal one.
Admin, you are confusing sources (generators, transformers) with load. For a generator or transformer, the power will be the same for any type of connection, and the phase current in the triangle is less than in the star. For the load, the type of engine, everything will be as I described above.- Evgeniy
“If you look through a telescope” ... even better, on the nameplate of the engine, you can see ... what? right ... answers to questions ... and they are written in the form In = ...
Example- P = 1.5 kW. then I (380) = 1500/380 * 1.732 = 2.3 (Simplified, without coefficients)
For I (220) = 1500/220 = 6.8.
Ohm's law is great. U = IхR. Simplified, Voltage is directly proportional to current.
Accordingly, the power is directly proportional to ... voltage ... and current .... The output is less voltage (or current, which is proportional) on the winding, less power. And then the essence arises ... DO NOT OVERLOAD THE MAINS. BUT we lose in waste.
Well, and, as a result, the customer's question "why the passport data is 3 cubic meters per hour, and this g ** but pumps only 1 cubic meter?"
- Evgeniy
- Kostantin
switching from star to delta provides a smooth start. when you press the start button, the windings are included in the star (for our voltage 380/220) and in the star it works at 660, after a certain time the windings switch to delta and already operates at a nominal voltage of 380 volts ...
- EVgen
Engine AIR132 M2 11 Kw / 3000 rpm. Can such a star-delta motor be connected?
- admin Post author
EVgen, yes if it is 660/380
- Dmitriy
Good day!
I'm a beginner, help me figure it out with this: "If the motor is connected to a star, then each winding is supplied with a voltage of 220 volts, and if the motor is connected in a triangle, then each winding has a voltage of 380 volts."
As I heard, by connecting the windings "to the star" - 380 V, and the "triangle" - to 220 V.
Maybe I misunderstood something, or a typo in the article? - admin Post author
Dmitry, Everything is correct in the article about the voltage on the motor windings. You have heard about the line-to-line voltage.
If between the phases in the 380V network and the motor is connected "to a star", then a voltage of 220V will be applied to each motor winding.We take a 660/380 motor, in such a motor, each winding is designed for 380V, that is, it must be connected to a triangle.
And at the time of launch, we connect it to the star, supply a reduced voltage of 220V to the windings. Accordingly, the starting current will be less.
And when the engine accelerates, we switch it to a triangle. - vitala
- admin Post author
- Yuri
Interesting to read.
Star-delta switching is used a) to reduce inrush currents; b) to increase the power factor of the electric motor and its degree of load. In the first case, for a 380/220 V network, it is necessary to take an electric motor whose passport has a voltage of 660/380 V. In the second case, the torque on the motor shaft, in addition to what has been said, should not exceed 30%. As for the diagram, it must be brought in accordance with GOST for designations, and this is a mixture of existing and long-unused designations. - vik
Hello everyone! I will say right away - for me, the concepts of phase and line current are subtle. In general, I will be grateful to someone who will explain whether this circuit is suitable for (and what options I have) for connecting an AIR90L2U3 electric motor (3 kW, approx. 3000 rev., 380v.). Three-phase network - four wires are included in the house. On the shield, the neutral is connected to the ground loop.
Thank you in advance. - vik
Warning questions regarding 220/380 and 380/660 I will say right away - the nameplate just says 380v. (No fractions)
- admin Post author
vik, the motor is low-power, it can be connected without this circuit.
Just through one starter and start-stop buttons. - vik
thanks, there are three wires under the cover, does that mean only a star? I still need a reverse.
- admin Post author
vik, If there are three wires under the cover, then a star.
To reverse, you need to swap two phases. Two starters are installed with interlocking of simultaneous switching on (necessarily electrical and additionally mechanical).Now an article is being prepared with diagrams about connecting motors, it will soon appear on the site.
- vik
admin, please tell me if the thermal relay TRN-10U3 is suitable for my engine (and how much is it necessary)?
Thanks. - admin Post author
vik, What brand of thermal relay is not important, the main thing is for what current.
If a separate machine is installed on the engine, then there is no special need for a thermal relay, since the machine already has thermal protection.
But there is no superfluous protection; therefore, it is better to put a thermal relay. - vik
And how do you know what current it is? There, on one side of the contact, a brand is stamped (TRN-10U3), on the other the number 10.
Or is the current regulated by a stepless regulator?
Thanks.- admin Post author
It's probably 10 amps. The regulator can smoothly select the current. Try to put it, it will work often, then it will not work.
- admin Post author
- vik
I have a reversible MP with three normally open contacts and one normally closed. I don’t understand how to connect it. If normally closed contacts are used for blocking (for duplicating mechanical), then how to fix three power contacts? It turns out that if you release the start button, the engine will stop rotating, right?
- admin Post author
vik, there are not enough contacts there should be four normally open and one normally closed contacts.
Through a normally closed contact, the coil of the second starter is connected to block.
One normally open contact is used to block the Start button, and three power contacts.
Additional contacts must be put on the starters.
- vik
admin, thanks for the help. You cannot add contacts. I see the solution in the following: change the main section of the starter into four normally open ones, carry out the reverse by holding the button (this completely covers my needs). The blocking remains only mechanical. How critical is this?
Thanks again. - vik
Yes, there is still a pair of normally closed contacts on the second starter. Will it be useful if it opens the main section while holding the reverse button?
- vik
And another question: on the one hand, somewhere it was that, from the point of view of safety technology, it is better to isolate the engine from the metal structure, and in the circuit, the neutral is grounded to the metal case in which it is assembled. How is it more expedient?
Thanks. - admin Post author
vik, the mechanical blocking is not very reliable, it may break over time and will have to be removed. Well, if there is no other way out, you can.
There has never been such a thing to isolate the engine from the metal structure. This structure and the motor itself must be grounded.
The neutral is grounded to the metal case just for safety. In case of breakdown of insulation to the case, a short circuit will occur and the machine will turn off the engine. - vik
admin, thank you so much for your help.
The device I'm trying to put together is a garden shredder. The motor will run in one direction 99% of the time. Reverse will only engage if the crop is wrapped around the cutting unit, so a held button would be even preferable.
I do not think that this device (if it works out) will be used by someone else besides me. Well, I will try to refrain from pressing two buttons at the same time, so there is a hope that the load on the mechanical blocking will not be very shock.
Thanks again. - Andrey
HELLO, I WANT TO FIND OUT WHAT THIS DIAGRAM WILL FIT IN MY CASE: ASYNCHRONOUS MOTOR 130 KW.
- admin Post author
Andrey, yes, if the voltage is suitable.
- Completely confused ...
On all sites in different ways. There is a motor (vacuum, water cooling), on the nameplate 380 volts, 5.5 kW. The terminal block on it is connected in a triangle.
http://s018.radikal.ru/i516/1203/44/1f6335630318.jpgIf I connect 380 will it be correct, or will it be correct to switch the terminals to a star?
Thank you in advance!
- admin Post author
Usually, they write 380/220 or 660/380. If only 380 is written, then it is correct to connect to the star.
It is safer to connect to the star to see how it will work, whether it will deliver the required power, measure the current.
If something is wrong it will be possible to switch to a triangle. - vik
2admin:
Good afternoon, I want to connect this device to protect against phase loss:
http://www.kriwan.com/en/Protection_and_Controls-Products-25,productID__182.htm
It is not clear that the contacts breaking the circuit (M2, M1) do not ring. This is fine? Perhaps they will close when the voltage is applied?
Thanks. - admin Post author
vik, the contacts are probably open, if you apply voltage, they should close.
It should turn off when at least one phase is missing, but here there are no three phases. - vik
It's logical, thanks.
- Glory
And such a question. An asynchronous motor connected by a star (three outputs) must be connected to a single-phase network, there is a starting circuit with resistance or capacity, and the capacity is starting and working, or only starting or only working. If the capacity is only the working motor from the button will start or not? If nichrome is used in the start, then the engine starts and the resistance is discarded. The question is, is it possible to use nichrome in one circuit for overclocking, and the capacity (working) to increase the engine power in operation? If so, what is the scheme? Hopefully not too confused. Thanks a lot in advance!
- admin Post author
- Glory
admin
Thank you, I will try, but I don’t want to disassemble the engine in order to add a fourth wire. - vik
2admin:
Good afternoon, I bought a used three-phase electric motor on the market as 1.5 kW (illegible on the nameplate), went online, and it looks like it is 0.75 kW. I was going to apply it in a device where there was a 1.1 kW single-phase. How critical is the difference and what can you think of? Can I connect it to a triangle?
Thank you very much in advance. - vik
2admin:
I am still waiting for your reply ... - admin Post author
vik, well, if you have already bought it, then bet the difference is not very critical. It will simply put out less power.
For example, if you put it on a pump, then a 0.75 kW motor will pump less water per unit of time than a 1.5 kW motor. And it will warm up more.
It is not worth connecting to a triangle, it can burn out. - vik
- vik
2admin:
Christ is Risen!
I apologize in advance for bothering me on such a day - is it necessary to connect a common point to the motor housing when connecting to a star, or only neutral? - admin Post author
vik, when connecting to a star, a common point can not be connected with anything at all. And connect zero to the motor body, and in another place the motor is still connected to ground. We usually do that.
If you wish, you can also connect the middle point to the body. - vik
Thanks to.
- Dimon
Good afternoon! I am finishing university right now, I have a special question in my diploma, regulation of asynchronous motors by changing the winding connection schemes from a star to a triangle, it is necessary to calculate the losses at different loads and connection schemes. motor 4a315s6 110kw, 380/660. can anyone help ???
- admin Post author
Dimon, the engine turns into a star only when started for just a few seconds. Then he switches to a triangle.
It even became interesting that if the engine is switched to a star at low load, and when the load is increased to a triangle.
Can it cut losses.
I think not, otherwise such schemes would be used everywhere. - PASS
please tell me if a three-phase 220v motor is connected to 380v, it will not burn? and how to do it correctly
admin writes:
31 Jan 2012 at 20:08Vitala, Such a motor needs to be connected only to a star, and when connected to a triangle, it will burn out.
Disappointed !!! It will burn out anyway! Admin, where did you study ?!
Three-phase voltage 380V (linear!) And three-phase voltage 220V (linear!) Are different quantities !!!
Three-phase motors 220V are easier to connect through a converter. The simplest is a three-phase motor connected to a single-phase 220V network.- Evgeniy
Excuse me, where did you see 220V three-phase?) In the house? Sorry, interphase 380 with a ruler of 220 ...
No, well, if 127 V is considered linear, then yeah.
So, the Admin is not as wrong as he did not ask for the full parameters. What did Vitala mean? 220/380? Or 127/220?- admin Post author
Evgeniy,
Line-to-line voltage is the voltage between phases. A Phase voltage is the voltage between phase and zero.
Although I agree it is necessary to clarify what kind of engine it is.And it often happens that the engine has only three leads in a star or triangle, it is soldered inside. and is designed for only one voltage, for example, 380V or 220V
A 220/380 motor for a 220/380 network is connected to a star. And for a 220/127 network in a triangle.
I did not come across 127/220 engines, and why such an engine is everywhere a 220/380 network.
- admin Post author
- Evgeniy
- admin Post author
PASS, and three-phase voltage 380V (linear!) And three-phase voltage 220V (phase!) Are almost the same values.
If the engine is 220/127. The easiest way is to rewind it. - PASS
In the same place it is clearly written "three-phase motor 220v" I have three of them and they work perfectly from the converter motor. And do not need extra haemorrhage with rewinding!
And I know the difference between phase and line voltages and CAM. - DIMA
SHEMA RABOTAET MALAKA
- Plague
"Switching the motor from star to delta is used to protect electrical circuits from overloads." Hmmm ... Actually, all the fuss is due to the increased starting torque, which can hardly be called smooth, “warm” and fluffy. That is, we deliberately overload the engine by current for a short time along the triangle and after a set of revolutions we switch to long-term star mode.
- admin Post author
Plague, if you need a smooth start, switch from star to delta is used, but you need a starting torque, then vice versa.
In practice, I have not come across switching schemes from a triangle to a star, more often a scheme from a star to a triangle is used. - Don Migeli
Why the engine
- Don Migeli
380/220 660/380 - this means if the triangle is the first value of the fraction, and if the star is the second?
Why can only the 660/380 be connected in the star-delta circuit?
- admin Post author
Don Migeli,
The lower the voltage in the fraction is phase and the greater is the linear.Because the electric motor only at the moment of starting in a few seconds switches to low voltage, and after starting it switches to normal operation.
For a 220/380 engine, the usual wiring diagram is a star, if it is connected to a delta it will burn out.
And for the 380/660 engine, the usual triangle scheme.
This is at a voltage of 220/380 - Don Migeli
Thanks for the answer, but will you tell me about the choice of cable? what to build on from the current on the nameplate or is the calculation needed?
- admin Post author
Don Migeli, from nameplate current or power
- admin Post author
- Don Migeli
if 22 kW, 46.2 A - then how does it turn out on each phase of 46A or 46 should be divided into 3 phases, can you tell in more detail?
- admin Post author
Don Migeli, 46A in each phase.
- admin Post author
- Don Migeli
- Andron
Good afternoon. Tell me how you can find out what connection of the windings of the motor is "star" or "triangle" ?? Three wires come out of it, but how is the connection in it unknown ?? I want to start it, but I don’t know which capacitor to install ??
- Nick
on the nameplate 220/380, the triangle is only 220. star 380 can be 220 with a decrease in torque. it all depends on what you want to get, high torque or limit the starting current. do not burn the engines.
- Sergey
Good afternoon, I have such a problem on the nameplate of the engine 380/660, but when switching from a star to a triangle, it knocks out the machine instantly. The engine worked fine after rewinding, before rewinding, is it possible that it was rewound incorrectly and how to check it?
- admin Post author
Maybe it was rewound 220/380, but it is more difficult, it is easier to count the number of turns on the burned out engine and wind the same amount.
It is necessary to measure the current into the star and compare it with the current on the nameplate, whether it is very different.
- admin Post author
- Sergey
I tried to run without load, the circuit works fine, the currents are below nominal. Changed the size of the pulley to reduce the load, now it does not knock out and the currents are normal. Thank you very much for your help.
- Sergey
Compressor with 7.5 sq.
Strongly sits the line and the engine does not fully accelerate.
I propose to change the diameter of the motor pulley, increase the cable cross-section from the meter to the compressor, and include it in the star.
Will these measures be enough, and what else can be done.- admin Post author
Sergey, First of all, increase the cable cross-section.
- admin Post author
- Sergey
With this I thought to start.
But there is still interest, for what purpose they installed a three-thousandth capacity for the compressor.
Usually before we met a compressor with motors for 900 or one and a half thousand, and this ???- admin Post author
Maybe with him the pressure is higher
- admin Post author
- Artur
The old 75 kV motor was launched from a star to a triangle, on the new one for some reason they indicated a connection with a D-D triangle. Can it be started up like an old motor?
- admin Post author
Yes you can
- admin Post author
- Alexander
Help me figure out the engine bought on the cheap by the overall dimensions of the AIR 180M but inside the 6 ends, there is no plate. How to deal with the diagram of its connection with a triangle or a star and how much speed will it give us and what power?
