Single-phase electric motor - a mechanism designed to be connected to a 220 V network. Such a unit is called single-phase due to only one working winding, although, in fact, it is a two-phase motor. Such devices can be used to drive various mechanisms used in the household, or for small production jobs.
Content
- Electric motor device
- Description of unit parts
- Mechanism models
- The principle of operation of the apparatus
Electric motor device
To start the starting winding of the motor, a centrifugal switch is provided in its composition. This detail distinguishes the basic design of such electric motors from three-phase units. In addition, the electrical mechanism consists of the following parts:
-
hulls; - stator;
- windings;
- rotor;
- shaft;
- bearing assembly;
- fan;
- junction box.
The centrifugal switch consists of a spring and special weights, specially selected to create a moment to turn off the starting winding. This device protects the electric motor from unnecessary wear of the contacts and contributes to more reliable operation of the entire mechanism. And also the design of a single-phase motor is distinguished from a three-phase by the presence of a starting capacitor. It is installed both directly in the engine and in an external launcher.
Description of unit parts
Typically, the motor housing is made of aluminum alloy or cast iron. Cast iron housings are heavy, so they are sometimes inconvenient to install. There are holes for ventilation in the case.
This part in the production scheme can be installed both horizontally and vertically. A stator is attached directly to the motor housing along the perimeter, which is a static winding.
It is imperative that the stator wires be impregnated with insulating material. The stator winding is made of enameled copper wire and impregnated with class H varnish. This contributes to high electrical and mechanical reliability of the windings and increases the overall life of the motor.
The rotor core is a high-carbon steel laminate structure pressed onto the shaft with subsequent thermal and chemical treatments.
The connection of the elements is considered to be short-circuited, which ensures a low moment of inertia and a high efficiency.
Directly the motor shaft itself is made of high quality steel, which gives it mechanical strength and avoids deformation as a result of operation. The bearing seats are cast from the following material:
- aluminum;
- cast iron.
Special springs are used to compress the bearings. Sealed ball bearings are mainly used as shaft supports, which eliminate the need for lubrication.
In some designs of 220-volt electric motors, roller bearings are used, which can reduce the radial load by 2 times. The fan for cooling the rotating parts of the engine is made of plastic or light metal.
Its work is protected by a metal case with ventilation holes. Currently, electric motors are available with a symmetrical radial or combined cooling system.
To circulate the cooling air inside the unit, diffusers are used, installed on two end shields. There is usually an aluminum alloy terminal box on top of the motor housing.
The location of the terminal block can be changed depending on the installation location of the electric motor. The general fastening of the engine is carried out using feet or end flange.
Mechanism models
There are many electric motors nowadays. They can be used both on a production scale and for private use. Among them there are the following models:
-
SMP-2TS - this brand is widely used in washing machines. This design is connected through ballast capacitors. - Lek 1.5 kW-750 - an engine with a horizontal platform, the maximum number of revolutions is 750 per minute. It is widely used in households to connect various devices.
- AIRE 56 B2 Is a popular brand of single-phase motors. They are mainly used for installing emery stones during grinding work.
- AASO-53 - models of this brand are produced in Italy and are very popular in many countries. They are widely used in heating systems as a drive for the main generator.
It is also worth noting the following models: AASO-63, AIR-71A2, CSCR, etc.
The principle of operation of the apparatus
When the electric motor is started, the electric current forms a pulsating magnetic field on the stator of the unit. In practice, two fields are formed, which rotate in different directions, but have equal amplitudes and frequencies.
When the rotor is stationary, two oppositely directed moments are formed around it. In such a situation, in the absence of starting mechanisms, the engine can remain in a static position. But with the help of a capacitor, which gives a short-term impulse to one of the moments, the motor starts to rotate.
This action is carried out by briefly pressing the start button until the rotor starts to rotate. The start-up phase is designed for an operating time not exceeding 3 seconds. Otherwise, electrical equipment will overheat.
Therefore, it is forbidden to hold the capacitor button longer than usual at the time of engine start. In order to avoid the failure of the engine at this moment, the use of a centrifugal switch and a thermal relay is provided.
The advantages of using these mechanisms include low cost, simplicity of design, long service life, operation from a 220 V network. Such units can be successfully used for household needs.
The disadvantages of such electric motors are: the complexity of starting, low efficiency, difficulties in adjusting the rotor rotation.
