How should the steps to repair the carbon brush (brush) of the generator set be carried out?

Companies using generator sets often find that there are carbon brushes (brushes) problems in the unit, which has caused production to remain unchanged for many customers. They have repeatedly contacted Jiangsu Haixing Power's after-sales response. Multiple safety notices have been reported continuously for several large generator sets , which caused major economic losses to the enterprise due to failure of carbon brushes or rotor current collector rings. When a fault occurs during operation of the carbon brush that is imported and exported, how to determine 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 is something that everyone needs to think carefully. In fact, if the carbon brushes of the generator set are maintained and used properly, there will be no problems. Nowadays, it is often reported that large generator sets have shutdowns caused by carbon brushes or rotor current collector ring failures, causing significant economic losses to the company.
There are many reasons for the appearance of carbon brushes in generator sets. They can be analyzed from three aspects: electromagnetic, mechanical and chemical aspects:
1. Electromagnetic factors: When reactive or excitation current is adjusted, the spark of carbon brushes has obvious changes. When commutating the exciter, the carbon brushes have poor contact with the commutation sheet and the contact resistance is too large; the thickness of the oxide film of the rectifier or slip ring is uneven, causing the carbon brush current distribution to be unbalanced; or the load changes suddenly, and sudden short circuits lead to abnormal voltage distribution between the commutation sheets; unit overload and imbalance; unreasonable selection of carbon brushes, unequal distance between carbon brushes; carbon brush quality problems, etc.
2. Mechanical factors: the center of the commutator is not straight, the rotor is unbalanced; the unit vibration is large; the insulation between the commutator plates is protruding or the commutator plate is protruding; the contact surface of the carbon brush is not smooth, or the surface of the commutator is rough, causing poor contact; the surface of the commutator is not clean; the air gap at each commutator end is not equal; the spring pressure on the carbon brush is uneven or the size is not suitable; the carbon brush is too loose in the brush holder and jumps, or it is too tight, and the carbon brush is stuck in the brush holder, etc. The unit's operating speed is reduced or the vibration is improved, and the spark will be reduced.
3. Chemical factors: The unit is running in a corrosive gas, or the unit's operating space lacks oxygen, and a layer of copper oxide film naturally forms on the surface where the commutator comes into contact with the carbon brush is destroyed. The commutator's already formed, approximately 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 commutators are contaminated, etc.

Specific steps for repairing and maintaining the carbon brush (brush) of the generator set
A. Operation inspection: Strengthen regular and irregular equipment inspection work. Under normal circumstances, staff must inspect the carbon brushes of the generator twice a day (once in the morning and once in the afternoon), use infrared thermometer to measure the temperature of the collector ring and carbon brush. During peak load in summer and when reactive power and voltage fluctuations are large, the temperature measurement interval should be shortened, and the replacement of new carbon brushes should be conducted for key inspections. Units with conditions should regularly use infrared cameras to measure the temperature of the current collector ring and carbon brush. And keep records of the operating conditions of the circuit inspection equipment.
B. Maintenance and replacement: Accept 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 grasp the process of replacing the carbon brush. The carbon brushes used in the same unit must be consistent and must not be mixed and used. Before replacing the carbon brush, carefully grind the carbon brush to make its surface smooth. The brush should have a 0.2 0.4 mm gap in the brush holder, so that it can move up and down freely in the brush holder. The distance between the lower edge of the brush holder and the commutator working surface is 2-3 mm. If the distance is too small, it will collide with the commutator surface, which is easy to damage and the distance is too large, and the brush jumps easily and 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 shall not exceed 10% of the total number of single poles. Carbon brushes with a carbon brush top 3mm lower than the top of the brush holder should be replaced as soon as possible. Carbon brushes of the same type must be used each time when replacing the carbon brush, but pay attention to saving and making full use of the carbon brush. The replaced carbon brush must be measured with a DC caliper meter to measure the flow of the carbon brush, and an infrared thermometer is used to perform temperature testing to prevent individual carbon brushes from overheating due to overcurrent. For obvious equipment problems such as the protrusions and depressions of slip rings or rectifier reversing plates, the opportunity of unit maintenance should be used for tightening and grinding. Strengthen maintenance quality and operation control to avoid the turbine oil leaking during operation due to poor maintenance quality or improper operation adjustment, throwing it onto the current collecting ring, and increasing the contact resistance between the carbon brush and the current collecting ring. The brush holder and brush holder should be carefully adjusted during large or minor repairs of the unit. When replaying and installing the brush holder, the angle and geometric position should be ensured in its original state. The sliding in and out sides of the carbon brush must be parallel to the commutator.
C. Daily maintenance: Clean and blow soot frequently, keep the light surface of the carbon brush and the rectifier slip ring clean. If there is strong wind, it must be cleaned in time afterwards. Adjust the spring pressure frequently. The pressure of the carbon brush spring must comply with the manufacturer's regulations to ensure that the carbon brush bears even pressure. Prevent individual carbon brushes from overheating, sparking, or burning and burning of brush braids. 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 the same and cannot be mixed and used. Staff performing maintenance should be very careful when inspecting and maintaining. The braid should be placed in the cap and fastened the cuffs so that the clothes and wipe materials should not be hung by the machine. When working, stand on an insulating pad and do not contact the two poles or one pole and the grounding part at the same time, nor do two people work at the same time. When adjusting and cleaning the carbon brushes and slip rings on the rotating motor, comrades with practical experience must do so.