7 reasons; why electric motor brushes sparkle From the article you will learn 7 reasons why power tool motor brushes sparkle. Electric motor device. And how to solve these problems on an angle grinder, rotary hammer and milking devices.
Poor brush contact with the collector
The electric motor spends part of its operating time in overheating mode. Under these conditions, carbon deposits form on the manifold. Poor contact will lead to increased spark formation from the brushes and more soot.
It is necessary to clean the collector surface with fine-grain sandpaper. Use a screwdriver to increase the stripping effect. Clamp the engine rotor into the chuck and at low speeds, sand the carbon off. After that, you need to finally polish it on a felt circle.
7 reasons why electric motor brushes sparkle
In household electrical equipment, collector motors are widely used. Small dimensions, lightness, ease of operation have led to their presence in angle grinders, hammer drills, circular saws, screwdrivers. The main disadvantage is increased wear of the brush-collector pair. Failure of this unit is predetermined by spark formation arising in it.
- The device of the electric motor and the principle of operation
- The reasons
- Wear of brushes
- Short circuit in the armature winding
- Malfunction in the stator winding
- Incorrectly installed brushes
- Poor brush contact with the collector
- Mechanical violations
The wear product of brushes is graphite dust; it is an additional source of increased sparking. Dust accumulates between the plates, which creates additional conditions for the spark formation process. Preventive work on cleaning the collector with sandpaper and cleaning up dirt between the plates will keep it clean.
The essence of the problem
The sparking of the brushes makes it impossible for the power tool to operate at full power. Since they are the connecting link in the electrical circuit, disruption of their operation leads to interruptions in the supply of current. This negatively affects the motor winding and reduces its service life.
Sometimes the fault may be in the brushes themselves. They quickly burn out due to cracks, chips, scratches, overheating. Replacing the old brush set will solve the problem. If the reason for the sparking is not in the brushes, then the new ones burn in the same way.
The armature shaft is fixed in the chuck of a torque mechanism (lathe, drill). Rotation starts, the abrasive is applied to the collector. Power pressure and the use of coarse sandpaper are excluded. The minimum grit value is 1000 P.
Using a multimeter, detect the presence of a breakdown in the armature winding. Set resistance test mode. Attach one probe to the lamella and the other to the contact of the corresponding winding path. The absence of an open circuit will be indicated by an audible signal. If there is no signal, this trace is broken. You will need to replace the armature or rewind its winding.
Determine if the bearings are running out. If it is found, replace the bearings and measure with a micrometer the diameter of the armature shaft edges at the points of its abutment to the assembly units.
There may be several reasons why angle grinder brushes spark and wear out strongly:
- Malfunction or increased wear of the brushes themselves;
- Violation of the contact density between them and the collector plates;
- Deterioration of the clamping action of the brush spring;
- Breakdown between collector lamellas;
- Axial runout of the armature due to bearing wear;
- Short circuit in the armature winding;
- Making structural damage to the mechanism during repair.
The reasons listed above are the result of improper operation of the angle grinder or poor assembly of its components.
In order to avoid the appearance of sparks in the area of the brushes, the rules for the safe use of the angle grinder should be observed.
- Do not turn on in case of high humidity, pronounced voltage drops in the network, dirt entering the brush block, contamination of the air duct grilles in the housing.
- Avoid overheating of the engine, load, slowing down the rotation of the mechanism at the time of operation.
- Do not use a low-power angle grinder for cutting heavy materials.
Why does the angle grinder spark
If the brushes spark on the angle grinder the reasons may be different. Can be pretty commonplace. For example, you bought a new angle grinder and are happy to plug it in for the first time. And in shock, disappointed, turn it off. Your purchase starts to sparkle strongly and, in addition to everything, smells like burnt.
Why do the brushes sparkle on the angle grinder when it’s new? Because the brushes have not yet got used. They should, over time, during the work of the angle grinder, rub in and then strong sparking and smell will disappear. This problem is solved if you just let the angle grinder run for a while. But if this problem occurs over time with your angle grinder, there are several reasons. And do not hope that the reason for the self-page during further work is the same as in the case of a new angle grinder.
First thing to find out why the angle grinder sparks check the same brushes. If the tool has quick access to the brushes, then simply unscrew the cap and take them out. Brushes should be intact, without chipping, not worked out to zero. The spring of the brushes must be intact, not crumpled or "planted". The wires inside the brush must be intact and not burnt out. If something is wrong, then we simply replace them. It is advisable to change both brushes at the same time. We use brushes of only the right size, otherwise the lamellas on the anchor will quickly fail.
The second reason why the angle grinder sparks and does not pick up speed is the burnt lamellas at the anchor. They can be carefully cleaned with a zero sandpaper. They should not have black carbon deposits. At the same time, if necessary, we clean the gaps between them from chips and dirt. The lamellas should be not only clean, but also smooth without working out. Otherwise, sparking and intermittent rotation will not be eliminated. For this whole operation you will have to disassemble the machine and remove the anchor.
If everything is in order with the above, then move on to more complex reasons. The anchor sparks onto the angle grinder. You can check the anchor at home if you have the necessary experience and a tester for ringing electrical circuits. First, the resistance between the lamellas is measured, it should be approximately the same everywhere. Next, check the breakdown on the armature body. For this, the probe of the device is closed on each lamella with the armature body. If the breakdown and the tester or probe beeps, then you are on the road for an anchor. By the way, the price of a new anchor is about half the cost of an angle grinder.
The next unpleasant breakdown can be a stator breakdown. It is also called for the resistance of all windings. It should be about the same. Also breakdown to the case. Repair or rewinding of the stator angle grinder is carried out in special workshops. Typically, such a breakdown occurs at the end of the life of the grinder or under improper operating conditions.
There are several other reasons why the angle grinder sparks. Bearings can be broken and, as a result, unbalance and armature runout. Cracks and defects in the magnet, which should not scroll or burst. The angle grinder must be clean, free from dust and chips, both inside and out. Watch out for voltage drops. Observe the instructions for use of the angle grinder. Do not forget that the household angle grinder is designed for short-term use after which the tool must cool down. Overheating can also be the reason why the brushes on the angle grinder burn. Remember that overheating of the tool and its breakdown is not a warranty case for your contact with a service center. Watch your angle grinder carefully and then it will serve you for a long time.
The mechanics of collector contacts contamination are as follows: the electric motor overheats, carbon deposits on the collector, which creates additional friction. As a result, the engine overheats again, even when operating at low rpm, the amount of carbon deposits increases, friction increases, and so on until the engine burns out at all.
The solution to the problem is obvious and consists in cleaning up contacts. Do it with the finest (zero) sandpaper:
- Remove the manifold with an anchor.
- Lightly sandpaper the contacts.
- Reinsert the module.
It is best to clean using a lathe to avoid disturbing the geometry of the part. But in practice, you can get by with manual work.
The main reason sparks appear even on a new engine is the mechanical interaction of the collector and brushes. Moving during tool operation from one collector contact to another, the brushes alternately create and break contact with each of them.
To make it easier to understand the principle, remember the situation when you pull out the plug of some electrical appliance from the outlet. When the circuit breaks, a spark is generated between the socket and plug. So it is in this case. Insignificant arcing is normal.
But if the sparks fly in a sheaf, this situation may be due to the following reasons:
- Collector contacts in carbon;
- Graphite dust from the brushes got between the contacts;
- A short circuit has occurred in the armature winding.
Why do the brushes sparkle at the screwdriver and what to do about it?
If the screwdriver sparks with rare and small sparks, this does not necessarily indicate a malfunction. A newly purchased tool can behave this way in the first 1015 minutes of work, while the brushes are grinding. If enough time has passed and the sparking does not stop, it is better to return the screwdriver.
But what if the problem manifests itself after years of using the power tool and the warranty has expired long ago?
Why electric motor brushes sparkle
Collector electric motors differ from other types of motors by the presence of a collector-brush assembly. The unit provides electrical connection of the rotor circuit to the circuits located in the stationary part of the motor and includes a collector (a set of contacts located directly on the rotor) and brushes (sliding contacts located outside the rotor and pressed against the collector).
During the operation of the commutator motor in a power tool, sparking of the brushes can sometimes be observed. In some cases, this symptom leads to an early breakdown of the power tool, and in some. Does not bode well. One way or another, it is useful in each case to understand what is the cause of the sparking, so that, if necessary, take the right measures in a timely manner. In this article, we will look at the causes of brush sparking, as well as measures to combat the problems causing this phenomenon.
Obviously, the intermittent mechanical contact of the brushes with the collector cannot but lead to arcing, because in fact, the rotor’s electrical circuit breaks and closes again many times a second.
The rotor contains a winding, which is a predominantly inductive load. The rupture of such a circuit is inevitably accompanied by a transient process, which is associated with the appearance of small arcs from the self-induction of the rotor winding or the rotor and stator windings. Of course, brushes wear out over time, as do the collector plates, but sometimes problems arise even before they wear out.
For the sake of fairness, we note that for the above reason, even a serviceable collector engine cannot work without sparks at all, there is always a small spark on the collector. A fully functional device normally reaches full power, develops working speed and still sparks a little. It is another matter if the sparking is strong, then justified concern arises.
Sparking brushes as a sign of wear
If the brushes are already badly worn out, simply due to the age of the engine, then the engine will not be able to reach full speed and reach full power. In this case, the sparking will be very strong, and the engine will not start the first time.
How can you verify that this is the case? If the worn brushes are pressed against the manifold with a screwdriver, the contact will become tight, and the engine will start. But as soon as the pressure is loosened, the sparks will reappear, the distance between the plates and the brushes will be filled with small arcs. The brushes are clearly worn out and should be replaced with new ones. Sometimes replacement is only possible together. With brush holders and springs.
There may be a short circuit in the rotor winding
The armature (rotor) winding of a collector motor traditionally contains several sections. If at least one is damaged, if there is an interturn short circuit, then more current will be supplied to one section than to the others. This will lead to overheating of the winding in one place, and to uneven sparking on the collector at some transitions on the plates, sparks will be stronger than on others. This requires rewinding an anchor or a completely new anchor.
Is the stator winding OK?
A similar malfunction is possible inside the stator, when part of the winding overheats, and strong arcing is observed near one of the brushes. Check the resistances of both halves of the stator winding, they must be the same. If one of the parts of the stator winding has a resistance that is much lower than that of the other, then rewinding or replacement of the stator is required.
A dirty collector is the reason for an unnecessary short circuit on it, as a result, extra sparks appear
Dust on the collector is formed as a result of the gradual wear of the brushes, this is graphite dust. It accumulates between the collector plates (lamellas) and creates unauthorized short circuits. Sparks appear due to short circuits. Simply clean the collector with sandpaper to remove any dirt between the lamellas.
Be sure to check how the brushes are located, whether one of them is displaced relative to the normal position, correct the brushes if necessary. When the brushes are positioned crookedly, graphite dust is generated in prohibitive amounts than with the correct positioning of the brushes.
Another reason for contamination is carbon deposits on the collector due to its overheating. When all other causes of sparking have been eliminated, it is necessary to clean the contacts from carbon deposits in order to improve the contact of the brushes with them.
If the contact is good, the resistance does not increase beyond the rating, and unnecessary sparks do not arise. You can clean off carbon deposits like graphite dust. Sandpaper, only rotating the rotor with the collector clamped in special pads.
Angle grinder brushes spark strongly cause
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Sparkle the brushes of the motor of the power tool
The brushes sparkle, does not develop revolutions at full power, does not periodically turn on (after a blow it starts to work), the consumption current is not overestimated.
the capacitor is intact, the armature is intact in appearance, the stator windings are in good order in appearance. The resistance when comparing the spirit of the windings is the same, the brushes are worn out by 60%.
while the engine is running, using a screwdriver (attention, the handle must be a dielectric), gently press the brushes against the armature, as a result the engine starts to work at full power (rpm increased).
we change the brushes for new ones, if this is not enough, then we replace the springs of the brush holders.
Both brushes sparkle, does not develop at full speed.
– Cleaning the collector with emery paper zeroing (using pads) in the direction of rotation of the armature, after which the dielectric spacers are cut between the collector plates with a cutter (preferably on a lathe).
In extreme cases, to clean the armature collector with a leg, use a drill, clamp the anchor in its chuck and at low speeds evenly lean the leg against the collector.
– If you have a proprietary puncher, then the cause of the sparking may be in the installation of non-native brushes.
– If both brushes spark strongly, the armature winding heats up. The anchor burned out the fastest, inter-turn circuit.
Only one brush sparks, it is possible that the stator of your hammer drill has burned out.
The stator can be checked at home. Measure the resistance of the windings with a tester, usually it is 4 Ohms, if the resistance of both windings is the same, then the stator is operational, if it differs, then it is necessary to rewind the stator winding.
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