Installation and Maintenance of Carbon Brushes and Slip Rings for Wire-wound Motor
 
 
1. Installation of brushes: The brushes should be installed into the brush grip to ensure that they can move up and down freely, and the clearance between the brush side and the inner wall of the brush grip should be between 0.1-0.3 mm to avoid the brushes from being stuck in the brush grip due to the excessive clearance and oscillation. The distance between the lower edge of the brush grip and the surface of the commutator should be guaranteed to be within the range of 2-3 mm. If the distance is too small, the brush grip is easy to hurt the commutator brush; if it is too big, the brush is easy to be upside down and lead to damage.
 
 
When grinding the arc surface of the brush, use glass sandpaper (do not use emery paper), put it on the commutator or collector ring, and apply the same spring pressure on the brush as when it is running.
 
Pump the sandpaper along the direction of motor rotation (the brush should be lifted up when pulling back the sandpaper), until the brush arc surface and the commutator or collector ring basically coincide with the basic, to remove the grinding down of the powder and sand particles, the motor idling for 30 minutes, and then 25% of the load running, to be brushes and the commutator or the collector ring contact is complete, the motor can be put into normal operation.
 
2、Brush pressure: The spring pressure applied to the brushes should be as uniform as possible, especially the brushes used in parallel, otherwise it will lead to the uneven load of the brushes. Otherwise, it will lead to uneven loading of brushes.
 
Otherwise, it will lead to uneven loading of brushes. The spring pressure is different for different motors. For motors with higher circumferential speeds, the brush pressure should be increased, but excessive pressure will increase brush wear. Brush pressure can be
 
The brush pressure can be adjusted according to the data in the brush technical performance table.
 
Replacement of new brushes: When the brushes are worn down to 2/3 or 1/2 of their original height, it is necessary to replace the brushes with new ones. When replacing the brushes, all the old brushes should be removed from the motor, and the new brushes should be of the same type and specification as the original brushes. The commutator or collector ring of the same motor is not allowed to mix two or more types of brushes.
 
4, brush maintenance: motor operation, commutator or collector ring surface often maintain a layer of bright brown oxide film, and to stabilise the brush contact voltage will be low friction coefficient, reduce brush wear on the commutator or collector ring. Oxide film is too thick, the contact voltage will increase, cause brush overheating and increase electrical loss. Oxide film is too thin, will increase the wear of brushes, commutator or collector ring, and easy to produce strong spark.
 
 
Oxide film formation, in the motor 25% of the rated load, easier, oxide film formed by the thickness of the motor environment related to the use of high temperature, humidity and corrosive gases, the commutator and collector ring is easy to form a thicker oxide film. On the contrary, in highland areas and thin air, the commutator and collector ring are not easy to form oxide film. For brushes used in special environments, brushes treated with appropriate impregnants should be selected.
 
The load on the brushes should not exceed the permissible values in the technical performance table for motors in continuous operation. All kinds of brushes have self-lubricating property, so it is forbidden to apply oil, paraffin and other lubricants on the commutator or collector ring.
 
5, commutator turning and cleaning: when the motor commutator or collector ring oval degree more than 0.02 mm, should be turning, grinding, so as to avoid the brush due to the commutator or collector ring eccentricity is too large and vibration.
 
The mica between the commutator pieces is not allowed to protrude, and the mica groove should be kept at a depth of 1~2 mm.
 
6、Part of the motor due to frequent starting, copper conductive ring life is short, frequent replacement, if changed to steel ring, the service life will be improved.
 
7, in order to avoid the collector ring discharge, require high pressure motors each time after the shutdown of the collector ring parts of the entire ash cleaning, check the carbon brush condition (whether in the brush box jammed, whether skewed, whether all the surface of the collector ring tightly, whether the pressure is too high or too low), when the carbon brushes are worn out only 25-30mm need to be replaced; when the surface of the collector ring is worn out after the emergence of grooves need to be replaced.