1 Carbon brushes
(1) Hardness: Compared with the original carbon brushes of the unit, the products produced by Shanghai Morgan joint venture have greater hardness and cause wear important mechanics.
(2) The resistance of the carbon brush itself: Since different batches of carbon brushes are mixed, their resistance coefficients are different, which causes a big difference in the increase of the temperature of the carbon brushes during operation, which leads to uneven current distribution of parallel carbon brushes, not only does the individual current exceed the norm, but wear increases.
(3) The contact resistance between the brush body and the brush braids is large (the connecting rivets and the brush braids change color), which results in the high temperature of the brush in carbon.
2 Brush holders
The structure of a set of custom brush holdersis not standardized compared to the original ones. The carbon brushes cannot move freely in the brush holders: due to. the carbon brushes in operation are not the lengths of the 36 parts are exactly the same, so the spring pressures are also different, and there is no tool to measure the pressure. It can only be measured by touch, so it is difficult to be sure. the spring pressure standard. Additionally, overheating the carbon brush will cause the spring to anneal, reducing pressure. As a result, the current of some carbon brushes is reduced.
3 Slip ring
(1) Since the slip ring was cut and polished during the carbon brush fire accident, it is much smaller than the original design diameter of 500mm, and The entire brush holder has not been modified accordingly, which is not conducive to effective contact.
(2) Thepolarity of the slip ring cannot be adjusted in time, which will also cause significant wear of the slip ring.
4 Brush holder
It can be seen from the contact surface between some carbon brushes and the slip ring that the center line of the carbon brush is not completely perpendicular to the circumferential section of the slip ring, but has a certain angle of inclination. Tilting will inevitably cause poor contact of the carbon brush, inconsistent spring pressure, inconsistent distance between the brush holder and the slip ring surface, and differences in the effective contact area of the carbon brush: there has burrs around the brush holder and is not smooth. , and it is easy to hang toner and dust, which will damage the carbon brush. The current difference will increase.
5 External environment
The slip ring and the brush devicecarbon brushes are close to the 10 watt generator, and there is oil mist, which affects the life of the carbon brush and slip ring. . The humidity of the surrounding air affects the formation of the carbon film of the slip ring, thereby affecting the conductive performance of the carbon brush.
6 Other aspects
The cooling air ducts of the slip ring and carbon brush are not smooth, and the powder blowing and suction function carbon is not strong, which causes the accumulation of carbon powder. into the groove of the slip ring cooling cloud line. When the ambient temperature on site increases, due to poor cooling effect, the friction temperature between the slip ring and the carbon brush increases. Some surfaces of the carbon brush exhibit combustion phenomena and the conductivity decreases, causing a deviation offluent.