There are several schemes for connecting electric motors. It all depends on what type of machine is being used. In everyday life, each person uses a variety of electrical appliances, about 2/3 of the total number have in their design electric motors of various capacities with different characteristics.
Usually, when appliances fail, engines can keep running. They can be used in other designs: make home-made machines, electric pumps, lawn mowers, fans. But here you need to decide which scheme to use to connect to the household network.
Design of electric motors and connection
In order to use electric motors for homemade devices, you need to properly connect the windings. The following machines can be connected to a single-phase 220 V household network:
- Asynchronous three-phase electric motors. Electric motors are connected to the network"triangle" or "star".
- Asynchronous electric motors powered by a single phase network.
- Combulator motors equipped with a brushed design to feed the rotor.
All other electric motors must be wired with sophisticated starter devices. But stepper motors must be equipped with special electronic control circuits. Without knowledge and skills, as well as special equipment, it is impossible to make a connection. You have to use complex wiring diagrams for electric motors.
Single and three-phase network
There is one phase in the household network, the voltage in it is 220 V. But you can also connect three-phase electric motors designed for a voltage of 380 V to it. Special circuits are used for this, but it’s almost impossible to squeeze more than 3 kW of power out of the device, as the risk of damaging the electrical wiring in the house increases. Therefore, if there is a need to install complex equipment that requires the use of 5 or 10 kW electric motors, it is better to run a three-phase network into the house. It is much easier to connect electric motors with a "star" to such a network than to a single-phase one.
What you need to connect the motor
The principle of operation of any electric motor is familiar to everyone, it is based on the rotation of the magnetic flux. When connecting single-phase electric motors, you don’t really need theory, so the following knowledge will suffice:
- You should have an idea about the design of the electric motor you are working on.
- Know what purpose the windings are intended for, and also be able to carry out installation according to the motor connection diagram.
- Be able to work with auxiliary devices - ballast resistors or starting capacitors.
- Know how an electric motor is connected using a magnetic starter.
It is forbidden to turn on the electric motor if you do not know its model, as well as the purpose of the conclusions. Be sure to check which winding connection is allowed when working on a 220 and 380 V network. All electric motors must have a metal plate that is attached to the housing. It indicates the model, type, wiring diagram, voltage, and other parameters. If there is no data, then it is necessary to ring all the windings using a multimeter, and then connect them correctly.
Connecting a commutator motor
Such electric motors are used in almost all household electrical appliances. They can be found in washing machines, coffee grinders, meat grinders, screwdrivers, heaters and other appliances. Electric motors are designed for a relatively short operating time, they turn on for a few seconds or minutes. But the motors are very compact, high-speed and powerful. And the motor connection diagram is very simple.
You can connect such an electric motor to a 220 V household network very simply. Voltage arrivesfrom the phase to the brush, then through the rotor winding to the opposite lamella. And the second brush removes the voltage and transfers it to the stator winding. It consists of two halves connected in series. The second output of the winding goes to the neutral power wire.
Features of turning on the motor
In order to turn the electric motor on and off, a button with a lock (or without it) is used, but a simple switch can also be used. If necessary, both windings are separated and they can be connected alternately. This achieves a change in the rotor speed. But there is one drawback of such motors - a relatively low resource, which directly depends on the quality of the brushes. It is the collector assembly that is the most vulnerable point of the engine.
How to connect a single-phase asynchronous motor
In any asynchronous electric motor, designed to be powered from a single-phase 220 V network, there are two windings - starting and working. As a “collector”, a cylindrical billet made of aluminum is used, which is mounted on a shaft. It can even be noted that the cylinder on the rotor is, in fact, a short-circuited winding. There are many schemes for turning on an asynchronous motor, but few are used in practice:
- Using a ballast connected to the start winding.
- With the start capacitor turned on.
- Using a push-button or relay starter, a starting capacitor included in the winding circuitstart.
Very often, a combination of a push-button or relay starter, as well as a permanently on run capacitor, is used. Instead of a relay, an electronic key on a thyristor is very often used. With this switch, a single-phase electric motor is connected with an additional group of capacitors.
Practical schemes
Asynchronous electric motors have a rather small starting torque. Therefore, it is necessary to use additional devices, such as starting relays or ballast resistors, as well as powerful capacitors for connecting single-phase electric motors. Windings in motors are made with division into several conclusions. If there are three conclusions, then one of them is common. But maybe four or two.
In order to understand which particular contacts a particular winding is connected to, it is necessary to study the motor circuit. If not, you will need to dial with a multimeter. To do this, switch it to resistance measurement mode. If there is a lot of resistance on a pair of leads, then this means that you measured two windings at the same time. Usually, the working winding of asynchronous motors has a resistance of no more than 13 ohms. In the launcher, it is almost three times higher - about 35 ohms.
In order to connect a single-phase asynchronous motor using a starter, you just need to correctly connect all the contacts with wires. In order to start the asynchronous, it is necessary to briefly turn on in the circuitadditional elements - a capacitor or ballast resistance. To turn off the electric machine, it is enough just to de-energize all the windings.
Three-phase motors
Three-phase electric motors have significantly more power and torque during start-up. Connecting a three-phase electric motor is simple only if there is a three-phase 380 V socket. But it turns out to be problematic to use such motors in domestic conditions, since not everyone has a three-phase network at home. The windings are connected according to the "star" or "triangle" scheme, it depends on the phase-to-phase voltage in the network.
But in the event that you need to connect such an electric motor to a household network, you will have to use a little trick. In fact, you have zero and phase in the outlet. In this case, "0" can be considered as one of the outputs of the power source, that is, the phase in which the shift is zero.
To make another phase, it is necessary to shift the power phase with an additional capacitor. There should be three phases in total, each has a shift relative to its neighbors by 120 degrees. But in order to make the shift correctly, it is necessary to calculate the capacitance of the capacitors. So, for every kilowatt of electric motor power, a working capacitance of about 70 microfarads is required, as well as a starting capacitance of about 25 microfarads. However, they must be designed for voltages of 600 V and above.
But it is best to connect 380 V three-phase motors withusing frequency converters. There are models that connect to a single-phase network, and with the help of special inverter circuits, they convert the voltage, resulting in the output of three phases, which are necessary to power the asynchronous motor.
