An electric motor anchor refers to the rotating part on which dirt is collected, soot is formed. In case of malfunctions, you can carry out diagnostics at home visually and with a multimeter. On rubbing surfaces there should not be chips, scratches and cracks. If any are found, measures are taken to eliminate them.
Typical malfunctions
The motor armature is not subject to wear during normal operation. Only brushes are replaced, measuring the permissible length. But with prolonged loads, the stator windings begin to heat up, which leads to the formation of soot.
Due to mechanical stresses, the motor armature can be skewed if the bearing assemblies are damaged. The engine will work, but the gradual wear of the lamellas or plates will lead to its final failure. But to save expensive equipment, it is often enough to carry out preventive repairs and the device can be used for a long time.
Negative factors affecting the motor armature include moisture on metal surfaces. Critical is the prolonged exposure to moisture and the appearance of rust. Due to red clusters and dirt, an increase in friction occurs, this increases the current load. The contact parts are heated, the solder can exfoliate, creating a periodic spark.
A service center can help, but it will require certain costs. You can deal with the breakdown yourself, having familiarized yourself with the question: how to check the motor armature at home. For diagnostics, you need a device that measures resistance and tools.
How is the malfunction diagnosed?
Checking the motor armature begins with the determination of the fault itself. A complete failure of this assembly occurs due to the scattered collector brushes, destruction of the dielectric layer between the plates, and also due to a short circuit in the electrical circuit. In case of sparking inside the device, it is concluded that the current collectors are worn or damaged.
Sparking of brushes begins due to the appearance of a gap at the point of contact with the collector. This is preceded by a fall of the device, a high load on the shaft during jamming, as well as a violation of the integrity of the solder at the terminals of the windings.
A malfunction on a running electric motor is manifested by typical conditions:
- Sparking is the main symptom of a malfunction.
- Hum and friction during rotation of the anchor.
- Sensible vibration during operation.
- Change of direction of rotation when the anchor traces less than a turn.
- The smell of melting plastic or strong heating of the body.
What to do when the listed deviations in the work appear?
The frequency of rotation of the motor armature is kept constant. At idle, the malfunction may not occur. Under load, friction is compensated by an increase in the current flowing through the windings. If deviations in the operation of the grinder, drill, starter become noticeable, then you need to remove the voltage supply.
Further use of the equipment may result in a fire or electric shock. First of all, it is recommended to inspect the product body, evaluate the wiring for integrity, the absence of fused parts and damage to the insulation. The temperature of all parts of the device is checked by touch. They try to rotate the anchor by hand, it should move easily, without jamming. If the mechanical parts are intact and there are no contaminants, they proceed to disassembly.
Diagnostics of the internal parts
The winding of the motor armature should not have soot, dark spots, similar to the effects of overheating. The surface of the contact parts and the gap area must not be clogged. Fine particles reduce motor power and increase current. It is not necessary to disassemble devices with a plug plugged into the network for the safety of work.
It is recommended to take pictures of the disassembly process to eliminate difficulties in the reverse process. Or you can write on a piece of paper every step of their actions. Some wear of brushes, lamellas is allowed. But if scratches are found, the cause of their origin should be found out. Perhaps this was facilitated by a crack in the body, which can be seen only under load.
Work with an ohmmeter
Sincere could happen due to the loss of electrical contact in one of the lamellas. To measure the resistance, it is recommended to place the probes on the side of the current collectors. Rotating the motor shaft, watch the dial. There should be zero values on the screen. If the numbers slip even a few ohms, then this indicates a burnt. When an infinite value appears, an open circuit is judged.
Regardless of the results, you should then check the resistance between each adjacent lamellas. It should be the same for each measurement. In case of deviations, it is necessary to inspect all the coil connections and the contact surface of the brushes. The brushes themselves should have uniform wear. With chips and cracks, they must be replaced.
Coils are connected to the core by wiring that could peel off. Solder often does not withstand impacts from falls. At the starter, the current through the contacts can reach 50A, which leads to the burning of poor-quality connections. External inspection determine the location of damage. If there is no malfunction, then measure the resistance between the lamella and the coil itself.
If there is no ohmmeter?
In the absence of a multimeter, a 12 Volt power supply and a bulb for the corresponding voltage will be required. Any motorist with this set will not have problems. The positive and negative terminals are connected to the plug of the electrical appliance. An incandescent lamp is placed in the gap. The result is observed visually.
The armature shaft is rotated by hand, the lamp burns without surges in brightness. If attenuation is observed, a faulty engine is judged. Most likely, there was an interturn closure. Complete disappearance of the glow indicates a break in the chain. The reasons may be non-contact of the brushes, a break in the winding or lack of resistance in one of the lamellas.
How to “revive” a faulty device?
Repair of the motor armature begins only after full confidence in the failure of the node. Scratches and chips on the lamellae are cleaned with a circular groove of the surface. Soot and soot can be removed with cleaning products for contact electrical connections. Broken bearings are repressed and replaced with new ones. It is important to keep the shaft balanced during assembly.
The rotation should be easy and without noise. Damaged insulation is restored, you can use ordinary electrical tape. Suspicious connections are best soldered again. For problems with the coils of the anchor, it is recommended to resort to rewinding, which can be done independently.
Coil Recovery
You can rewind the motor anchor in a garage, only you need to be careful when applying each turn. Copper wiring is selected similarly wound. The section can not be changed, this will lead to a violation of the high-speed modes of the engine. Dielectric paper is required to separate the windings. Coils at the end are varnished.
You will need a soldering iron and skills to use it. The joints are treated with acid, rosin is used to apply tin-lead solder. When dismantling the old winding, the number of turns is counted and the same amount of new winding is applied.
The case must be cleaned of old varnish and other inclusions. A file, sandpaper or burner is suitable for this. Sleeves are made for the anchor, the material is electrotechnical cardboard. The resulting blanks are laid in grooves. Wound coils should be done in right turns. Conclusions from the side of the collector are rewound with kapron thread.
Each wire is soldered to the corresponding lamella. The assembly should end with the next measurements of the resistance of the contact joints. If everything is normal and there are no short circuits, you can check the operation of the electric motor under voltage.