Connection diagram for a three-phase 220. Starting a three-phase motor from a single-phase network without a capacitor

One of the reasons for connecting a three-phase motor to a single-phase circuit is that the supply of electrical energy to industrial facilities and for domestic needs is fundamentally different.

For industrial production, electrical enterprises manufacture electric motors with a three-phase power system and you need to have 3 phases to start the engine.

What if you have purchased motors for industrial production and need to plug into your home power outlet? Some skillful specialists, with the help of simple electrical circuits, adapt the electric motor to a single-phase network.

Winding connection diagram

To understand a person who first encountered a similar problem, you need to know how a three-phase motor works. If you open the connection cover, you can see the block and the wires connected to the terminals, their number will be 6.

A three-phase electric motor has three windings and, accordingly, 6 leads, they have a beginning and an end, and are connected in electrical configurations called "star and delta".

This is interesting, but in most cases, standard switching is star-shaped, since delta connection leads to a loss of power, but the engine speed increases. It so happens that the wires are in an arbitrary position and are not connected to the connectors or there is no terminal at all. In this case, you need to use a tester or ohmmeter.

You need to ring each wire and find a pair, these will be the three windings of the motor. Then we connect to the "star" configuration as follows: start-end-start. We clamp three wires under one terminal. There should be three conclusions, so further commutation will take place to them.

It's important to know: a single-phase power supply system or - "phase and zero" is organized in the household network. This configuration must be used to connect the motor. From the beginning, we connect one wire from the electric motor to any wire of the network, then, to the second end of the winding, we connect the network wire and there one end of the capacitor unit.

The last wire from the motor and the unconnected contact of the set of capacitors remain free, we connect them and the circuit for starting a three-phase motor into a single-phase network is ready. They can be graphically depicted as follows:

• A, B, C - lines of a 3-phase circuit.
• Ф and О - phase and zero.
• C is a capacitor.

In industrial production, a 3-phase voltage supply system is used. According to the PUE standards, all network buses are marked with letter values ​​and have the appropriate color:

A - yellow.

B - green.

C - red.

It is noteworthy that regardless of the position of the phases, in, the bus "B", with a green color, should always be in the middle. Attention! The phase-to-phase voltage is measured by a special device that has passed the state inspection and by a worker who has the appropriate tolerance group. Ideally, the line-to-line voltage is 380 volts.

Electric motor device

Most often, we get our hands on electric motors with a three-phase asynchronous operation scheme. What is an engine? This is a shaft on which a squirrel-cage rotor is pressed in, on the edges of which there are sleeve bearings.

The stator is made of transformer steel, with a high magnetic permeability, cylindrical shape with longitudinal grooves for laying the wire and a surface insulating layer.

Using a special technology, the winding wires are placed in the stator channels and isolated from the housing. The symbiosis of the stator and the rotor is called an asynchronous electric motor.

How to calculate the capacitance of a capacitor

To start a 3-phase motor from a household network, it is necessary to perform some manipulations with the capacitor units. To start the electric motor without "load", you need to select the capacitance of the capacitor based on the formula 7-10 mF per 100 W of engine power.

If you look closely at the side of the electric motor, you will find its passport, where the power of the unit is indicated. For example: if the motor has a power of 0.5 kW, then the capacitance of the capacitor should be 35 - 50 mF.

It should be noted that only "constant" capacitors are used, in no case "electrolytic". Pay attention to the inscriptions on the side of the case, they speak about the capacitance of the capacitor, measured in microfarads, and the voltage for which they are designed.

The starting capacitor block is assembled according to this formula. Using the motor as a power unit: connect it to a water pump or use it as a circular saw, an additional capacitor bank is required. This design is called - working capacitor blocks.

They start the engine and, by serial or parallel connection, select the capacitance of the capacitor so that the sound from the electric motor comes out the quietest, but there is a more accurate method for selecting the capacitance.

For a verified selection of a capacitor, you must have a device called a container store. Experimenting with different connection combinations, you achieve the same voltage value between all three windings. Then the capacitance is read and the required capacitor is selected.

Necessary materials

In the process of connecting a 3-phase motor to a single-phase network, you will need some materials and devices:

• A set of capacitors with different ratings or "capacitor box".
• Electric wires, type PV-2.5.
• Voltmeter or tester.
• 3-position switch.

Basic tools should be at hand: voltage indicator, dielectric pliers, electrical tape, fasteners.

Parallel and series connection of capacitors

The capacitor is an electronic component and with different switching combinations, its nominal values ​​may vary.

Parallel connection:

Serial connection:

It should be noted that when the capacitors are connected in parallel, the capacitances will add up, but the voltage will decrease, and vice versa, the serial version gives an increase in voltage and a decrease in capacitance.

In conclusion, we can say that there are no hopeless situations, you just need to make a little effort and the result will not be long in coming. Electrical engineering is a cognitive and useful science.

How to connect a three-phase motor to a single-phase network, see the instructions in the following video:

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

Asynchronous versus commutator: how to distinguish

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

How the collector motors are arranged

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

Such motors are produced only single-phase, they are often installed in household appliances, since they allow you to get a large number of revolutions at the start and after acceleration. They are also convenient in that they easily allow you to change the direction of rotation - you just need to change the polarity. It is also not difficult to organize a change in the speed of rotation - by changing the amplitude of the supply voltage or the angle of its cutoff. Therefore, similar engines are used in most household and construction equipment.

The disadvantages of collector motors are high operating noise at high speeds. Remember a drill, grinder, vacuum cleaner, washing machine, etc. The noise during their operation is decent. At low revs, collector motors do not make as much noise ( Washer), but not all tools work in this mode.

The second unpleasant moment - the presence of brushes and constant friction leads to the need for regular Maintenance... If the current collector is not cleaned, contamination with graphite (from washable brushes) can lead to the fact that adjacent sections in the drum are connected, the motor simply stops working.

Asynchronous

An asynchronous motor has a stator and a rotor, it can be single and three-phase. In this article, we consider the connection of single-phase motors, therefore, we will only talk about them.

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

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

In single-phase capacitor motors, the capacitor winding runs all the time. Two windings - main and auxiliary - are offset relative to each other by 90 °. This allows the direction of rotation to be changed. The capacitor on such engines is usually attached to the body and by this sign it is easy to identify it.

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

Connection diagrams for single-phase asynchronous motors

With starting winding

To connect a motor with a starting winding, you need a button, in which one of the contacts opens after switching on. These opening contacts will need to be connected to the starting winding. There is such a button in stores - this is PNVS. Her middle contact is closed for the hold time, and the two outer ones remain closed.

The appearance of the PNVS button and the state of the contacts after the "start" button is released "

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

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

If there are four pins, they are called in pairs. Find two pairs. The one in which the resistance is less is the working one, in which the greater is the starting one. After that, we connect one wire from the starting and working windings, we bring out the common wire. In total, there are three wires left (as in the first option):

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

With all these

single-phase motor connection

We connect all three wires to the button. It also has three contacts. Be sure to put the starting wire on the middle contact(which closes only during start-up), the other two are extremelyno (optional). We connect a power cable (from 220 V) to the extreme input contacts of PNVS, connect the middle contact with a jumper to the working one ( note! not with a common). That's the whole circuit for switching on a single-phase motor with a starting winding (bifilar) through a button.

Condenser

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

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

Circuit with two capacitors

There is also a third option for connecting a single-phase motor (asynchronous) - install both capacitors. It turns out something in between the options described above. This scheme is implemented most often. It is in the figure above in the middle or in the photo below in more detail. When organizing this circuit, a PNVS-type button is also needed, which will connect the capacitor only not at the start time, while the motor "accelerates". Then two windings will remain connected, and the auxiliary one through the capacitor.

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

When implementing other schemes - with one capacitor - you will need an ordinary button, automatic machine or toggle switch. Everything connects there simply.

Selection of capacitors

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

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

The operating voltage of these capacitors must be 1.5 times higher than the mains voltage, that is, for a 220 volt network, we take capacitors with an operating voltage of 330 V and higher. And to make the start easier, look for a special capacitor for the starting circuit. They have the words Start or Starting in the marking, but you can take the usual ones as well.

Changing the direction of movement of the motor

If, after connecting, the motor works, but the shaft rotates in the wrong direction, which you want, you can change this direction. This is done by changing the windings of the auxiliary winding. When the circuit was assembled, one of the wires was fed to the button, the second was connected to the wire from the working winding and a common one was brought out. This is where you need to transfer the conductors.

The 220V electric motor is a simple and widespread device. Due to this voltage, it is often used in household appliances... However, it is not without its drawbacks. We will talk about what these electric motors are, about their application, disadvantages and ways to solve problems, as well as about the possibility of connecting to the network in the article.

Single-phase devices. Description

If it is necessary to connect a universal collector motor with series excitation, the winding is connected to the collector-brush assembly. After the shaft is loaded by the device with which the motor will operate, the required voltage is supplied.

Typically, brushed motors are direct current are low voltage. Therefore, to connect a 3000 rpm electric motor. min 220V, it is necessary to use an appropriate power supply unit with a transformer and rectifier.

Connecting a three-phase motor

Nowadays, it is not uncommon for motorists to use an electric motor. If it needs to be replaced or repaired, then the question may arise about how to connect the electric motor to the 220V network. A three-phase motor can be easily activated without calling a specialist, using the recommendations below.

A screwdriver, thermal relay, electrical tape, an automatic machine, and a tester can come in handy as tools.

detailed instructions

The old motor is removed and the neutral wire is marked with electrical tape. If it is reinstalled, then the neutral wire can be easily determined using the indicator. At the end of it, the light will not light up.

Fittings with a magnetic starter, as well as with an automatic machine and a thermal relay are added to the new engine. The armature is installed in the shield.

The thermal relay is connected to the starter. When choosing the latter, you need to be sure that it matches the power of the motor.

The armature terminals of the input are connected to the terminals of the machine, except for the neutral wire. The output terminals are connected to the same thermal relay. At the output of the starter, a cable is connected directly to the motor.

With a power of less than one kilowatt, the machine can be connected without going through the magnetic starter.

To connect the electric motor, remove the cover. On the terminal strip, the leads will be connected in a delta or star shape. The ends of the cable are connected to the strips. With a star shape, the contacts are connected alternately.

If the leads are randomly located, then a tester is used. It is connected to the ends, looking for the windings. After that, they are connected as in the form of a star, and the leads of the coils are collected to a point. The rest of the ends connect the cable.

Cover the engine with a cover and check the operation of the mechanism. If the shaft rotates in the wrong direction, any wires at the input are simply swapped.

Household electric motors are single-phase motors, they are often called by mistake ("two-phase motors") because they will be used in a network with a voltage of 220V. In this regard, single-phase motors are called 220v electric motor or 220v motor. Electric motors of the AIRE series (single-phase motors - "household electric motors"), asynchronous single-phase squirrel-cage capacitor motors, are designed to operate from an alternating current voltage of 220 V and a frequency of 50 Hz. It is allowed to operate from a 230 V, 50 Hz and 220, 230 V, 60 Hz mains. Single-phase motors are made with a two-phase winding on the stator ("two-phase motors"). To reduce the influence of ambient temperature on the capacitance of capacitors, they should be placed in places that are least subject to temperature fluctuations. During engine operation, it is recommended to periodically monitor the capacitance value of the capacitor.

Operating conditions

• Voltage and frequency: 220 V at a frequency of 50 Hz.
• Climatic version: U2, U3, U5, UHL, 2, T2.
• Operating mode: S1.
• Basic version protection: IP 54.
• Cooling degree - IC 041.
• Heat resistance class of insulation: electric motors are manufactured with insulation of heat resistance class "B" or "F" in accordance with GOST 8865-93.
• The nominal values ​​of climatic factors are in accordance with GOST 15150-69 and GOST 15543.1-89.
• Dust content of the air is not more than 2 mg / m3.
• Mechanical design group M1 in accordance with GOST 17516.1-90.
• Impact of vibration loads for engines corresponding to the 1st degree of severity in accordance with GOST 17516.1-90.

Application area of ​​single-phase motors

A single-phase asynchronous motor is designed to drive mechanisms. In particular, pumps, ventilation and other household equipment. Electric motors with a voltage supply of 220V are equipped with both one and two capacitors (operating and starting). Electric motors of the AIRE, AIRMUT, AIRUT, ADME, AISE, AIS2E series (single-phase with two capacitors), the latter are suitable for use on equipment requiring a large starting torque: woodworking machines, conveyors, compressors, lifts, etc., used to drive small-scale mechanization: feed choppers , concrete mixers, etc. The power supply is carried out from the AC 220V. As a rule, the motors are supplied by the manufacturers equipped with capacitors (the consumer only needs to connect the motor to a single-phase network according to the connection diagram). Mounting versions of single-phase motors and their overall and connecting dimensions correspond to common industrial motors of the AIR series (AIRM, 5A, ADM, etc.). Explanation of designation: AIRE, AIRMUT, AISE - a single-phase electric motor with a two-phase winding and a working capacitor. AIR3E, AIR3UT - a single-phase electric motor with a three-phase winding and a working capacitor.

An example of a conventional designation for an air motor:

AIRE 100S4 U3 IM1081

• AIRE -
  • A asynchronous,
  • AND unified series (Interelectro)
  • R binding of capacities to installation dimensions (P according to GOST, C - according to (CENELEK, DIN)
  • E single phase motor
• 100 -the size of the motor (height between the center of the shaft and the base)
• S- installation dimension along the length of the bed
• 4 - number of poles
• U3-climatic version and category of placement
• IM1081- execution on paws

Constructions according to the method of installation:

• IM1081 (paws)
• IM2081 (feet + flange)
• IM3081 (flange)

Constructions according to the method of installation: IM1081

Design by mounting method: IM1081 - on feet with one cylindrical shaft end.

IM1081

Constructions according to the method of installation: IM2081

Design by mounting method: IM2081 - on feet with one cylindrical shaft end.

Overall, installation and connection dimensions IM2081

The need to use a three-phase asynchronous electric motor independently most often arises when home-made equipment is installed or designed. Usually, in dachas or in the garage, craftsmen want to use homemade emery machines, concrete mixers, tools for sharpening and trimming products.

Using three-phase asynchronous motor by yourself

Here the question arises: how to connect an electric motor designed for 380 to a 220 volt network. In addition, it is important both to connect the electric motor to the network, and to provide the necessary indicator of the coefficient of performance (COP), to maintain the efficiency and operability of the unit.

Features of the engine device

Each motor has a plate or nameplate where the technical data and the winding twisting diagram are indicated. Y stands for star connection and ∆ for delta connection. In addition, the plate indicates the mains voltage for which the electric motor is intended. The wiring for connecting to the network is located on the terminal block, where the winding wires are led out.

To designate the beginning and end of the winding, the letters C or U, V, W are used. The first designation was in practice earlier, and English letters began to be used after the introduction of GOST.

It is not always possible to use a motor intended for a three-phase network for operation. If 3 outputs are brought to the terminal block, and not 6 as usual, then connection is possible only with the voltage indicated in the engineering specifications. In these units, a delta or star connection has already been made inside the device itself. Therefore, it is not possible to use a 380 volt 3-pin motor for a single-phase system.

You can partially disassemble the engine and convert 3 pins to 6, but this is not so easy to do.

There are different schemes of how best to connect devices with parameters of 380 volts to a single-phase network. To use a three-phase electric motor in a 220 Volt network, it is easier to use one of 2 connection methods: "star" or "triangle". Although it is possible to start a three-phase motor with 220 without capacitors. Let's consider all the options.

The figure shows how this type of connection is made. In the operation of the electric motor, you should additionally use phase-shifting capacitors, which are also called starting (Descent) and working (Sat.).

Star connection type

In a star connection, all three ends of the winding are connected. For this, use a special jumper. Power is supplied to the terminals from the beginning of the windings. In this case, the beginning of the winding C1 (U1) through parallel connected capacitors goes to the beginning of the winding C3 (U3). Next, this end and C2 (U2) must be connected to the network.

In this type of connection, as in the first example, capacitors are used. In order to connect the twists according to this scheme, 3 jumpers are required. They will connect the beginning and end of the winding. The conclusions coming from the beginning of the C6C1 winding through the same parallel circuit as in the case of the "star" connection are connected to the output coming from C3C5. Then the resulting end and the output of C2C4 should be connected to the network.

Connection type "Triangle"

If 380 / 220VV indicators are indicated on the nameplate, then connection to the network is possible only according to the "triangle".

How to calculate capacity

For a working capacitor, the formula is applied:

Srab. = 2780хI / U, where
U - rated voltage,
I - current.

There is another formula:

Srab. = 66xP, where P is the power of the three-phase electric motor.

It turns out that the 7μF capacitance of the capacitor is designed for 100W of its power.

The value for the capacity of the starting device should be 2.5-3 orders of magnitude more than the working one. Such a discrepancy in capacitance indicators for capacitors is required, because the starting element is turned on when a three-phase motor is operating for a short time. In addition, when turned on, the highest load on it is much greater, it is not worth leaving this device in the operating position for a longer period, otherwise, due to phase current imbalance, after a while the electric motor will start to overheat.

If you use an electric motor for operation, the power of which is less than 1 kW, then the starting element is not required.

Sometimes the capacity of one capacitor is not enough to start work, then the circuit is selected from several different elements connected in series. The total capacity for parallel connection can be calculated using the formula:

Ctot = C1 + C1 +… + Cn.

In the diagram, a similar connection looks like this:

About how correctly the capacitance of the capacitors is selected, it will be possible to understand only in the process of use. Because of this, a scheme of several elements is more justified, because with a larger capacity, the engine will overheat, and with a smaller one, the output power will not reach the desired level. It is better to start the selection of capacity with its minimum value and gradually bring it to the optimal one. In this case, you can measure the current using a current measuring pliers, then select the best option will become easier. A similar measurement is made in the operating mode of a three-phase electric motor.

Which capacitors to choose

To connect an electric motor, paper capacitors (MBGO, KBP or MPGO) are most often used, but they all have small capacitive characteristics and are quite bulky. Another option is to select electrolytic models, although here you will have to additionally connect diodes and resistors to the network. In addition, when the diode breaks down, and this happens quite often, the capacitor will begin to flow alternating current which could lead to an explosion.

In addition to capacity, you should pay attention to the operating voltage in home network... In this case, you should select models with technical indicators of at least 300W. For paper capacitors, the calculation of the operating voltage for the network is slightly different, and the operating voltage for this type of device should be higher than 330-440VV.

Network connection example

Let's see how this connection is calculated using an example of a motor with the following characteristics on the nameplate.

Engine characteristics

So, let's take a three-phase asynchronous motor with a connection diagram for a 220 Volt network with a "triangle" and a "star" for 380 Volts.

In this case, the power of the electric motor taken for example is 0.25 kW, which is much less than 1 kW, a starting capacitor is not required, but general scheme will look like this.

To connect to the network, you need to find the capacity of the working capacitor. To do this, you should substitute the values ​​in the formula:
Srab. = 2780 2A / 220V = 25 μF.

The operating voltage of the device is selected above 300 volts. Based on this data, the corresponding models are sorted. Some options can be found in the table:

Dependence of capacitance and voltage on the type of capacitor

Thyristor key connection

A three-phase electric motor designed for 380 volts is used for single-phase voltage using a thyristor switch. In order to start the unit in this mode, you need this diagram:

Three-phase electric motor diagram for single-phase voltage

The work used:

• transistors from the VT1, VT2 series;
• resistors MLT;
• silicon diffusion diodes D231
• thyristors of the KU 202 series.

All elements are rated for 300 Volts and 10A.
A thyristor key is assembled, like other microcircuits, on a board.

Anyone who has the initial knowledge in creating microcircuits can make such a device. When the power of the electric motor is less than 0.6-0.7kW, when the thyristor switch is connected to the network, heating of the thyristor switch is not observed, so additional cooling is not required.

Such a connection may seem too complicated, but it all depends on what elements you have in order to convert a 380W motor into a single-phase one. As you can see, using a three-phase motor for 380 through a single-phase network is not as difficult as it seems at first glance.

Connection. Video

The video tells about the safe connection of emery to a 220 V network and shares advice on what is needed for this.