What are the steps to repair the carbon brushes (brushes) of the generator set?

useGenerator setCompanies often find problems with carbon brushes (electric brushes) in their units, which causes production instability for many customers. They have repeatedly contacted Jiangsu Haixing Power for its after-sales response. Multiple safety reports have been issued, and several large-scale incidents have been reported in succession.Generator set, shutdown accidents caused by carbon brush or rotor collector ring failures have caused large economic losses to the company. When a fault occurs during the operation of the carbon brush that introduces and exports current, everyone needs to think carefully about how to identify the type and nature of the fault so as to deal with the fault as soon as possible and ensure the stable operation of the equipment. In fact, if the carbon brushes of the running generator set are properly maintained and used, they will not cause problems. Nowadays, it is often reported in the news that large generator sets have shutdown accidents caused by carbon brush or rotor collector ring failures, causing large economic losses to enterprises.
There are many reasons for the occurrence of carbon brushes in generator sets, which can be analyzed from three aspects: electromagnetic, mechanical and chemical aspects:
1. Electromagnetic factors: When the reactive power or excitation current is adjusted, the sparks of the carbon brushes will change significantly. When the exciter is commutating, the carbon brushes and commutator segments are in poor contact, and the contact resistance is too large; the thickness of the oxide film on the commutator or slip ring is uneven, causing unbalanced current distribution in the carbon brushes; or sudden load changes, and sudden Short circuit causes abnormal voltage distribution between commutator segments; unit overload and imbalance; unreasonable selection of carbon brushes, uneven spacing between carbon brushes; quality problems with carbon brushes, etc.
2. Mechanical factors: The center of the commutator is incorrect and the rotor is unbalanced; the unit vibrates greatly; the insulation between the commutator segments protrudes or the commutator segments protrude; the contact surface of the carbon brushes is not ground smoothly, or the surface of the commutator is rough and causes contact Defective; the surface of the commutator is not clean; the air gaps under each commutation pole are not equal; the spring pressure on the carbon brush is uneven or inappropriate; the carbon brush is too loose in the brush holder and jumps, or the carbon brush is too tight in the brush holder. The brush is stuck in the holder and so on. If the operating speed of the unit is reduced or the vibration is improved, sparks will be reduced.
3. Chemical factors: The unit operates in corrosive gases, or the operating space of the unit lacks oxygen. The naturally formed copper oxide film on the surface in contact with the commutator and the carbon brush is destroyed, and the already formed, approximate The commutation of the linear resistance no longer exists, and the commutator sparks intensify during the process of re-forming the oxide film on the contact surface. The commutator (or slip ring) is corroded by acid gas or grease. The carbon brushes and commutator are contaminated, etc.

Specific steps for overhauling and maintaining generator set carbon brushes (brushes)
A. Operation inspection: Strengthen regular and irregular equipment inspections. Under normal circumstances, staff must inspect the generator carbon brushes twice a day (once in the morning and once in the afternoon) and measure the collector ring with an infrared thermometer. And the temperature of carbon brushes, during summer peak load period and when reactive power and voltage fluctuations are large, the temperature measurement interval should be shortened, and the new carbon brushes should be replaced with key inspections. Units that have the conditions should regularly use infrared thermal imaging cameras to measure the temperatures of collector rings and carbon brushes. And keep records of the operating conditions of patrol inspection equipment.
B. Maintenance and replacement: Check and accept the newly purchased carbon brushes. Determine the inherent resistance value of the carbon brush and measure the contact resistance of the carbon brush lead. The resistance value must comply with the manufacturer and national standards. Strictly control the carbon brush replacement process. The carbon brushes used in the same unit must be consistent and cannot be used interchangeably. Before replacing the carbon brush, carefully grind the carbon brush to make the surface smooth. The brush should have a gap of 0.2 to 0.4 mm in the brush holder, and it can move up and down freely in the brush holder. The distance between the lower edge of the brush holder and the working surface of the commutator is 2-3 mm. If the distance is too small, it will collide with the surface of the commutator and be easily damaged. If the distance is too large, the brush will jump and cause sparks. Strive to achieve a carbon brush contact surface greater than 80% of the carbon brush cross section. Replace frequently, but do not replace too many carbon brushes multiple times. The number of carbon brushes replaced at one time should not exceed 10% of the total number of single poles. Carbon brushes with the top of the carbon brush 3mm lower than the top of the brush holder should be replaced as soon as possible. Each time the carbon brush is replaced, The same type of carbon brushes must be used, but attention should be paid to saving and making full use of the carbon brushes. The replaced carbon brushes must be measured with a DC caliper meter to measure the carbon brush shunt and an infrared thermometer for temperature testing to prevent individual carbon brushes from overheating due to overcurrent. For obvious equipment problems such as bulges and dents in slip rings or commutator segments, use the opportunity of unit maintenance to tighten and grind. Strengthen the quality of maintenance and operation control to avoid leakage of turbine oil during operation of the unit due to poor quality of maintenance or improper operation adjustment, throwing it onto the collector ring and increasing the contact resistance between the carbon brush and collector ring. The brush holder and brush holder must be carefully adjusted during major or minor repairs of the unit. When playing back and installing the brush holder, the angle and geometric position must be kept in the original state. The sliding in and out edges of the carbon brush must be parallel to the commutator.
C. Routine maintenance: Clean and blow dust frequently to keep the smooth surface of carbon brushes and commutator slip rings clean. In case of strong wind or afterward, they must be cleaned in time. Frequently adjust the spring pressure. The pressure of the carbon brush spring must comply with the manufacturer's regulations so that the carbon brush can bear even pressure. Prevent individual carbon brushes from overheating or generating sparks, or the brush braids from being scorched and burned out. If problems occur during the operation of carbon brushes, they must be eliminated in time to avoid a vicious cycle and endanger the normal operation of the unit. The carbon brushes used in the same unit must be consistent and cannot be used interchangeably. Maintenance staff should be particularly careful when performing inspections and maintenance. Hair braids should be placed in caps and cuffs should be fastened to prevent clothes and wiping materials from getting caught on the machine. When working, stand on the insulating mat and do not touch two poles or one pole and the grounded part at the same time, nor can two people work at the same time. When adjusting and cleaning carbon brushes and slip rings on a rotating motor, it must be done by comrades with practical experience.