Repair and testing of the washing machine motor (collector)
Washing machines can use different types of electric motors. The most common are the following:
Direct drive motors
Collector
And asynchronous
These electric motors have their own operating characteristics. For example, in order for an asynchronous motor to work normally, we need a special phase-shifting capacitor. Most washing machines produced a long time ago worked using this method.
Nowadays, a washing machine uses a special control system to control this type of engine. And in order to test the quality of an asynchronous engine without a special stand or test machine, you will have to work hard.
It will be no less difficult to independently check the performance of an electric motor with a direct drive. This drive is used in some models of modern washing machines. When checking them, difficulties may arise due to the fact that they are connected to the SMA tank. In addition, in order to test this type of electric motor, a control system is also needed.
Methods for checking a commutator motor
You can test brushed motors without any problems and even at home. The bulk of engines of this type are connected according to the following scheme:
In the diagram you can see that the power supply to the engine goes through the circuit: two hundred and twenty volts - control triac - reverse relay contacts (II or I) - stator winding - and rotor.
To switch the stator winding in the SM, a relay is used and contact groups of the command apparatus are used.All of them are located in the control module of the machine.
The stator winding includes 2 sections. This design reduces the influence of various interferences that may occur due to sparks on the collector.
A change in the direction in which the drum of the machine rotates is created by changing the polarity of the stator winding. Some washing machines have a tap for the stator winding. It is activated when squeezing clothes. With such a system, electricity is connected to one of the outer terminals and the outlet described above. And when the stator winding is connected through the outer terminals, the machine engages in the normal washing mode. And her drum rotates slowly.
In order to test the operation of the engine, a specialist connects the stator and rotor windings alternately. And they connect them to electricity. See below for a schematic representation:
This method of verification also has its disadvantages. For example, with this testing you still cannot be sure that the engine is working one hundred percent. Even when the shaft is spinning, this does not mean that you can guarantee that under various operating modes of the machine no malfunctions or obvious defects will appear.
In addition, this scheme does not include any protection. And if suddenly during operation the electric motor can “short”, then it will most likely quickly become unusable. In order not to expose the engine to unnecessary danger, one more link is included in the testing circuit. You can use a heating element from a washing machine or a powerful lamp (over five hundred watts) as it. The ballast is connected as indicated in the diagram:
And if short circuits occur, the heating element will increase its temperature due to the influence of electricity. There is also another option for checking the operation of the motor. It is necessary to connect the windings in the same way as in the second circuit. And power everything using a special autotransformer, which has a power of more than 500 watts. This method makes it possible to more clearly control the speed of revolutions and will allow you to respond to any surprises in a timely manner. In order to protect the entire process, you can use a five or ten amp fuse.
Instead of a laboratory transformer, you can also use an electronic regulator. One that is designed to control loads of a given power. If you are good at electronics, you can make it yourself using the appropriate circuit.
There is another option for performance testing. It is necessary to monitor how strong the sparking occurs between the brushes and the commutator. If it sparks strongly, then most likely the washing machine motor is faulty.
Main causes of electric motor malfunction
The main reasons for a washing machine motor failure may be as follows:
Malfunctions of the collector lamellas,
Breaks in rotor and stator windings,
Worn motor brushes.
Lamella malfunctions most often occur due to short circuits in the windings.
Broken lamellas
Due to breakdowns, the lamellas may lose contact with the rotor winding section. They can also heat up too much and even peel off. The lamellas are fixed to the collector with an adhesive. And the electrical connection with the sections of the rotor winding is created by special hooks.One of the most common failures of this engine part is the breaking of the cord in the rotor section at the junction with the lamella.
It is much worse if, due to excessive heating, the lamella has peeled off. Such a breakdown occurs due to short circuits in the winding sections, between the lamellas and rotor jamming. This defect occurs because electricity passes through the lamellas significantly above the operating level.
This can happen when the bearings jam or when a top-loading washing machine starts washing with the drum flaps not locked in the closed position. More often than not, this defect in the lamellas tells us that there are some other breakdowns of the electric motor or that the machine is not being operated correctly.
Minor delamination, not exceeding half a millimeter, is removed by grooving the collector on a special machine. After this, you need to carefully inspect and clean all parts of the part from dust and chips and remove burrs.
In order to determine the presence of this malfunction, you can slowly rotate the rotor with your own hands. If you hear a characteristic cracking sound, then most likely there is a problem.
Worn motor brushes
If the washing machine motor brushes are worn out, then it’s time to replace them with new ones. You can find new brushes in specialized stores. They can also be purchased to order. The easiest way to find suitable parts for a washing machine is to use search engines on the Internet. In Google or Yandex search results you can find organizations that sell these spare parts. And by calling them, you can find out if the brushes you need are in stock or place an order for them.
To find out if the brushes are worn out, you can use a visual inspection or check how much the engine sparks during operation.
By the way, quite strong sparking can occur when the brushes are still new and have not gotten used to the internal parts of the engine. Another reason to decide that the brushes are worn out is incomplete rotation of the machine drum. Quite often this happens when there is a problem with the drive belt. For example, when it breaks or slips off a pulley. Also, the cause of what is happening may be a short circuit between the turns of the engine winding.
In most cases, brushes from other motors will not work. It is necessary to purchase brushes designed specifically for your motor.
The hardness of the brushes can affect how long they will last. But very hard brushes can damage the commutator over time.
Short circuits and breaks in rotor and stator windings
Has the engine become less powerful? Short circuits occurring between the turns of the winding are possible. As we already wrote above, in the event of such a breakdown, the drum of the machine may not rotate or may not rotate completely.
Has the electric motor stopped working? Most likely, there was a break in the stator windings. This can also happen due to too much heating of the motor housing due to short circuits in the same motor windings. If the engine has heated up to a temperature of over ninety degrees, a special thermostat designed for protection will operate. The normal temperature during operation of the electric motor should not exceed eighty degrees. As you have already read above, if the engine overheats and short circuits, the lamellas may peel off.
In order to check whether there is a break in the windings, you can use a multimeter (tester). Turn it into ohmmeter mode. Then hook it to the adjacent slats. In different shaft positions, the resistance between adjacent lamellas should be the same (from 0.1 to 0.4 Ohm).
In addition, short circuits in the washing machine motor winding may occur due to insulation failure. Unfortunately, in this case the entire engine will have to be replaced. Or re-create the winding. Which is not very easy. And we don't recommend doing it yourself.
A short circuit in the engine of the machine can cause many other malfunctions. For example, the contacts of the control module connectors may become unusable, the power triac, reverse relay, etc. may fail.
Washing machines can use different types of electric motors. The most common are the following:
Has the engine become less powerful? Short circuits occurring between the turns of the winding are possible. As we already wrote above, in the event of such a breakdown, the drum of the machine may not rotate or may not rotate completely.
Very useful, thank you!