The Little Things I Didn’t Know About Small DC Motors | Hackaday
At the heart of every electric RC vehicle is the motor, or the “driving force” Sealed endbell motors need a lot of running to break in their hard Let it dry, put some oil on the bushings or bearings, and let it sit for a few hours. The Little Things I Didn't Know About Small DC Motors The only consumer items I can think of that regularly break this rule are very cheap children's toys, . The faster you pump it, the more power it takes in a linear relationship, so you draw a line for the load from the origin .. Graphite is a dry lubricant. Motomate combines a brushless motor, movement and position control, together with .. As soon the rotor begins to turn, the fixed brushes make and break . The graph for this relationship does not vary with the supply voltage of constraints caused by inertia, viscous friction and dry friction inside the.
Most motors are held in with a couple of screws and some washers on them. Remove those screws and keep a small tray around to keep your small parts and your pinion in. If you have a sealed motor, you are limited to how well you can clean it. Take a clean toothbrush and gently brush the dirt and grime away from the bushings or bearings—take care to not push the dirt in deeper.
How to get the most out of your brushed RTR motor - RC Car Action
Another option is compressed air, but only use this after you get the majority of the dirt off the exterior of the motor. Then, use the compressed air and blow dirt out of the motor using the vent holes; you can even try using the motor mounting holes to blow the motor out. Running it partially submerged in water helps break them in faster.
Water dipping is a trick old-school guys used to break in their motors, but it would also help clean your brushed motors. Never use this method on brushless motors.
Breaking In BRUSHED Motor (Wet Or Dry)? - R/C Tech Forums
You will need a cup of water and your motor wired back to your electronics so it works just like if you mounted it in the vehicle. Put enough water into the cup so that you can submerge your motor in it. Next, turn on your radio and your electronics just like you were going to run the vehicle. Run the motor, and hold it in your hand while you turn the throttle trim up until the motor is running at a nice, steady rpm. The paint mixers high running speed and infrequent use make it a decent candidate for hooking directly to the motor.
This is for a lot of reasons. The first is that they typically spin very fast, 6, — 15, rpm is not atypical for even the tiniest motor. Or a mere 1.
However, if you start to combine lots of rotations together using a gear train, you can start to get some real power out of it, even with the friction losses. Both of these are taking for granted that their torque needs are low and their speed needs are high, or that the motor burning out is no real loss for the world at least in the short term.
Most of these motors are hundreds of loops of very thin enameled wire wrapped around some silicon steel plates spot welded or otherwise coerced together. This means that even a small heat event of a few milliseconds could be enough to burn through the 10 micrometer thick coating insulating the coils from each other.
Making Contact Pololu has the clearest picture of the different kind of brushes inside these small motors. If the resistive imbalance is still high, you may want to move to Position Y, downstream of the contactor. If the imbalance is still evident at Position Y, testing at the motor connection box, Position Z, will isolate the motor from the power circuit and determine which is the problem area.
Insulation Condition This refers to the insulation between the windings and ground. High temperatures, age, moisture and dirt contamination all lead to shortened insulation life. It has been said that if plants would just use the space heaters available to keep the insulation dry, then doubling the life of our motors would not be out of the question.
Insulation systems today are better than ever and are able to handle higher and higher temperatures without significant reduction in life. However, we are still finding ways to destroy our insulation much earlier than should be expected.
Keep in mind that although insulation is many times involved in a failure, this fault zone is heavily influenced by other problems. The power circuit for one can heavily influence the insulation. If a high resistance connection exists upstream of the motor, which develops better than a 5 percent voltage imbalance, and we continue to run the motor at its normal horsepower rating, we will see a shortened insulation life.
Reverse sequence currents developing rotating magnetic fields in the opposite direction will not only reduce the torque capability, but can allow the temperature to rise out of control and exceed even the degree Celsius limit on your Class F insulation systems. Was the insulation system the real cause of the motor failure or was it just a symptom? It is easy to diagnose the evident insulation failure as the fault mechanism but it will happen again with a different motor if the problem is not fixed.
The Little Things I Didn’t Know About Small DC Motors
Then what will the explanation be? Again, testing with a Megger is not going to tell you everything, but it is a good start when it comes to insulation testing. Something that people often overlook when it comes to the IEEE Institute of Electrical and Electronic Engineers limits on resistance to ground is the reference to 40 degrees C.
Simply Megger testing with no regard to temperature will result in resistance to ground readings, which swing heavily from high to low readings, depending on the temperature of the windings.
Temperature correcting the readings will not only meet the IEEE testing requirements, it will give a much better trend as seen in Figure 5. Figure 5 We must realize that moisture contamination may cause the temperature corrected reading to be invalid. Ensure the heaters are energized when the motor is not running to prevent this from happening. An insulation test that has fallen out of the spotlight is the Polarization Index test.
Applying a constant DC voltage, in the form of a Megger test, for a period of 10 minutes will result in a gradual increase in the resistance to ground RTG reading. This is a result of charging the insulation system, much like a capacitor, which causes a reduction in the absorption current.
Therefore, the reduction of this absorption current must result in an increase in the resistance. Unfortunately, motors with unstable insulation systems can give values close to or greater then a 2. Figure 6 In Figure 6, when the minute reading approximately megohms is divided by the one-minute reading approximately megohmsthe result is 1. This nearly meets the IEEE specification as a good insulation system, and would probably be accepted in the field. You can see, however, that this insulation system is very unstable.
Always look at the PI Profile and not just the index. A limiting factor about DC resistance to ground testing is that the DC signal will many times not give the best evaluation of the true insulation condition. The insulation on a motor is a natural dielectric material. Therefore, it is a poor conductor of DC. AC, however, does not allow the dielectric to charge and will pass through the dielectric much easier.