The characteristics of carbon brushes are classified into static characteristics and dynamic characteristics.

• Static characteristics include bulk density, hardness, resistivity, and bending strength. These parameters are defined for each material type and serve as a measure to verify whether the product has been manufactured according to the specified conditions. Therefore, static characteristics are commonly used for quality control purposes. Since they indirectly affect motor performance, they can also serve as a reference when selecting materials.

• Dynamic characteristics include friction coefficient, contact voltage drop, and maximum peripheral speed. These parameters directly affect motor performance and are therefore important guidelines for material selection. However, since they may vary depending on the motor specifications and operating environment, evaluation through actual motor testing is essential.