Slip ring series synchronous motors and asynchronous motors using slip ring motors are widely used in the industrial field, and they operate under various harsh conditions. Although these motors do not have the commutation function of DC motors, they also have problems such as brush collector rings or special wear, brush vibration, and sparks in daily life with commutators. The strange thing is that in terms of brush materials, the collector ring not only uses graphite brushes, but also metal graphite brushes to improve the current density of the brushes. Therefore, factors such as special residual swelling must also be considered. Even for high-speed motors, such as turbogenerators or those operating in fully enclosed gas and hydrogen media, there are many problems.

The collector ring material requires high mechanical strength, is an excellent electrical conductor, and has corrosion resistance and wear resistance and smooth sliding contact characteristics when sliding in contact with the brush. Generally speaking, steel collector rings have excellent wear resistance and high mechanical strength, so they are mostly used in synchronous motors with large differences in collector ring wear caused by polarity.

Generally speaking, steel collector rings have excellent wear resistance and high mechanical strength, so they are mostly used in synchronous motors with large wear differences, and the polarity will cause the collector rings. Steel, which can be machined into complex structures, is an easily available and inexpensive material that is widely used in synchronous electrical machinery including hydroelectric generators at low peripheral speeds. For slip rings, the main emphasis is on mechanical strength and wear resistance at high peripheral speeds, for example in turbogenerators, sometimes using forged steel. In addition, when corrosion resistance is required, stainless steel may be used, but the sliding characteristics of stainless steel are not messy, and improper contact with the brush will cause the brush to jump, which may easily cause excessive temperature rise or special wear of the brush, so the use should be doubled. Notice. Compared with steel collector rings, copper collector rings such as bronze castings have excellent sliding properties, so they are widely used. Slip ring brushes are worn or exceptionally worn.

The collector ring is connected with the brush. When the abrasiveness of the brush is too strong and the material of the collector ring is too soft, step wear corresponding to the width of the brush easily occurs on the collector ring. Especially for fully enclosed motors with high temperature and low humidity, it is more likely to cause excessive wear of brushes or collector rings. That's how ghost marks are formed. There are only small scars at the beginning, and the brush has poor current collection in these parts and sparks occur. Once a spark occurs, the scar will gradually deteriorate and expand, and finally form a scar that communicates with the size of the brush sliding contact surface. Therefore, care must be taken even if the brushes of the slip rings generate very small sparks.