Good motors are in washing machines, even when the latter breaks down and is thrown away - the motors are left and later used in the household (for example, for a mini-machine). Here we will consider a typical motor from an automatic washing machine (new and old type) and a diagram of its separate connection to 220 V. But first, let me lay out a little boring theory, which you can skip by moving on to the second, practical, part of the article.
Theory of operation of a 220 V electric motor
Asynchronous motors for single-phase networks are mainly motors with two-phase windings and an auxiliary phase taken from a capacitor. Such motors are used in household appliances. A similar motor is used, in particular, to drive a washing machine. In addition to two-phase winding motors, three-phase winding motors are sometimes used in some other household appliances.
During direct starting, the motor can receive a current from the network that significantly exceeds its rated value. This current is called the motor starting current, and its value varies in the region Ir = 5-7In .
One way to reduce the inrush current is to use a star-delta switch. A motor designed to operate the stator in a triangular connection at a given mains voltage is connected to the star system at the time of start-up:
Due to the reduced voltage supplied to the stator winding phase and the change in connections from delta to star, the current taken from the network will be reduced by three times compared to the starting current in a delta circuit. However, when connected to a star, the motor has three times less starting torque, which makes it impossible to use this method during heavy starting (with a heavy load).
Advantages of asynchronous motors for washing machines
The electric motor that rotates the drum is the heart of the washing machine. The drive in the very first versions of the machines was belts that rotated the container with laundry.
But today the asynchronous unit, which converts electricity into mechanical energy, has been significantly improved.
Most often, washing machine circuits contain asynchronous electric motors, consisting of a stator, which does not move and serves as both a magnetic circuit and a supporting structure, and a moving rotor that rotates the drum. An asynchronous motor operates due to the interaction of the magnetic alternating fields of these nodes.
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Asynchronous motors are divided into two-phase, rare, and three-phase.
The advantages of asynchronous units include:
- simple design;
- simple maintenance, including replacement of worn bearings and
- periodic lubrication of the electric motor;
- silent operation;
- relative cheapness.
- Of course, there are also disadvantages:
- low efficiency;
- big sizes;
- low power.
Such motors are usually installed on inexpensive models.
Capacitor for electric motor
For small motors (<1 kW), the value of the starting capacitor can be determined from the relationship:
C [uF] = (1800 x Pn) / U2
where Pn [W] – rated motor power, U [V] – supply voltage.
This formula is also suitable for calculating the starting capacitor value for single-phase start-phase motors.
For larger motors (>1kW) a capacitance of around 70uF/1kW is suggested. It is necessary to use starting capacitors with operating voltages of 400..630 V AC.
You can omit the calculations and simply connect a standard motor from the washing machine to 1 phase 220 V through a 7 microfarad capacitor connected between the required terminals. Connect the first power wire to the middle, and the second, depending on the direction of rotation, to one of the capacitor wires. The power drop will be 30% - this is in theory.
The issue of choosing a capacitor is easily resolved. Here are examples of capacitance values for different engine powers.
Pn [W] 90 120 180 250 370 550 750 1100 S [µF] 4 5 6 8 12 16 20 30
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The rotation power in the washing machine is the same in both directions. These are motors with a typical connection for a single-phase motor. The main winding is connected directly to 220 V and a phase winding is connected in parallel with it along with a series-connected capacitor. If you reverse the phase winding wires, the motor will rotate in the other direction, but the power will be slightly less. This circuit works during the spin cycle. The same for slow and fast rotations - the capacitance switches inside the washer from 7 µF to 16 µF. Read more about the capacitor here
Possible breakdowns
Now you know how to connect an electric motor to give it a whole new life, but a small incident may occur: the motor will not start.
It is necessary to understand the reasons and find a way to solve the problem. Check engine heating after running for 1 minute. In such a short period, the heat does not have time to transfer to all components and the place of active heating can be clearly fixed: the stator, bearing assembly, or something else.
The main factors for rapid heating are:
Then we examine every 5 minutes of work; it is enough to do this 3 times. If the reason is the bearing, then it needs to be disassembled, lubricated or replaced. During further operation, we regularly monitor the heating of the motor. Avoid excessive overheating, as repairs can cause huge damage to your home budget.
Source
Connecting the motor from the SMA
This motor contains two independent windings:
for synchronous speed 3000 rpm - two-phase winding.
for synchronous speed 500 rpm - symmetrical three-phase winding . The three-phase connection system allows you to change the rotation speed by switching the power supply to the winding.
An older type motor usually has 5 wires, black, blue, white, red and green. A series of measurements were carried out to determine the windings and the resistance between them:
- Blue-black 85 Ohm
- Blue-green 85 Ohm
- Black-green 80 Ohm
- White-blue 15 Ohm
- White-red 30 Ohm
Connecting an old electric motor requires finding the starting winding using a multimeter.
- ON - initial winding . It is designed to start the engine only and starts at the very beginning until the engine begins to rotate.
- OB – field winding . This is the work winding that runs constantly and constantly turns the motor.
- SB – button from which voltage is supplied to the starting coil and turned off when the engine starts.
Motor connection diagram in an old washing machine
Everything is more serious here. You need to find 2 pairs of pins that match each other using a multimeter (toaster). To do this, fix the device on any of the terminals and find the paired one using a probe. The two remaining pins will be the second pair automatically.
Now determine the location of the working and starting windings by measuring the resistance. The starting point (PO), which creates the starting torque, is found by its higher resistance. The disturbance winding (OB) creates a magnetic field.
Connecting the electric motor from a new washing machine
If you look at the terminal block with the wires on the front, usually the first two wires on the left are the tach wires, which measure and regulate the rotation speed of the washing machine motor. We don’t need them - they are crossed out with a cross.
In different models of washing machines, the wires differ in color, but the connection principle remains the same. You just need to find the necessary wires by testing them with a multimeter.
A working tachogenerator in a quiet state usually has a resistance of 50-100 Ohms. You will immediately find these wires and disconnect them.
If you need to change the engine speed in the opposite direction, simply drag the jumper to the other pins. Look at the diagrams to see what it looks like.
Two contacts go through the brushes to the rotor windings, and the other two contacts go to the stator winding. The remaining contacts are a sensor for measuring the motor rotation speed. The rotor and stator windings are connected in series and by changing the ends of one of the windings, you change the direction of rotation. Without an electronic regulator, the engine will accelerate to several thousand revolutions per minute (as at maximum spin).
- Read how to regulate the motor rotation speed from the SMA here.
How does an asynchronous motor work?
To understand the principle of its operation, we recall the same picture as in the previous example: a frame (but without half rings) is placed between the magnetic poles. The magnet is made in the shape of a horseshoe, the ends of which are connected.
We begin to slowly rotate it around the frame, watching what is happening: until a certain moment, no movement of the frame is observed. Then, at a certain angle of rotation of the magnet, it begins to rotate behind it at a speed less than the speed of the latter. They work asynchronously, which is why the motors are called asynchronous.
In a real electric motor, a magnet is a winding placed in the stator slots to which current is supplied. The rotor is a frame. In its grooves there are short-connected plates. That's what they call it - short-circuited.
Call the master
If you are unable to repair and replace the Indesit washing machine motor on your own, you need to seek help from a specialist. There are several ways to find a master:
Most craftsmen do not charge money for a visit if the person agrees to pay for the repairs. This information needs to be clarified at the stage of calling a specialist. Before choosing a repairman, you need to study reviews of his work. Moreover, it is better to do this on a site other than the one on which he placed an advertisement about his services.
Approximate prices:
As a rule, the brushes are guaranteed for 6 months, and the motor is 1 year. Prices do not include the cost of parts (if they need to be replaced).
A lot of important and useful information about repairing Indesit washing machines is presented in this section.
