Are brushes considered a wear element

2021-08-23 11:28:45

Although brushes are considered to be wear components and are a very small part of the motor, the absence or failure of the brushes will cause the motor to stop. These failures may occur, for example, due to accelerated wear of the brushes, incorrect contact pressure, or current non-uniform distribution, resulting in high temperatures, arcing, and damage to the motor. The continued existence of one of these abnormal conditions may lead to catastrophic failure of the motor, and therefore economic loss.

Normally, the motor can be checked only after the motor has stopped. The method to assess the condition of the brushes and other parts of the motor is to perform physical inspections on site by the operator. Usually, inspections require the use of measuring instruments. For example, a dynamometer is used to measure the pressure of the brush spring, a diameter gauge is used to measure the axial measurement of the brush holder, and an external diameter gauge is used to measure the length of the brush. Although these measurements are important, the pressure at which the brush is installed is fundamental because it is related to the friction of the brush on the slip ring. Too high pressure will accelerate the mechanical wear of the brushes, while too low pressure will cause arcing, which will change the electronic components in the ring. The correct measurement can enable the inspector to check whether the parameters of the pressure mechanism are within the recommended range, so that the carbon brushes are evenly worn, so as to comply with the range specified by the maintenance procedure. Generally speaking, the maintenance plan aims to find a point at the intersection of pressure and wear at the contact point of the brush.