Carbon brush failure factor and maintenance method of generator set

Carbon brush failure factor and maintenance method of generator set

The carbon brush is a brush. If the carbon brush of the generator set in operation is improperly maintained and used, it will cause accidents to reduce the load and even stop the machine.

Factors that cause carbon brush failure

1. Electromagnetic factors:

When the reactive or excitation current is adjusted, the spark of the carbon brush changes significantly. When the exciter is reversing, the carbon brush and the commutator are in poor contact, the contact resistance is too large; the oxide film of the commutator or the slip ring is not thick, causing the carbon brush current distribution to be unbalanced; or the load suddenly changes, and the sudden The short circuit causes the voltage distribution between the commutator segments to be abnormal; the unit is overloaded and unbalanced; the carbon brush selection is unreasonable, and the carbon brush spacing is not equal;

2. Carbon brush quality issues and more.

Mechanical factors: the center of the commutator is not right, the rotor is unbalanced; the vibration of the unit is large; the insulation between the commutator segments is convex or the commutator segments are convex; the contact surface of the carbon brush is not smooth, or the surface of the commutator is rough and the contact is poor; The surface of the commutator is not clean; the air gap under each commutating pole is not equal; the spring pressure on the carbon brush is not uniform or the size is not suitable; the carbon brush is too loose in the brush grip to jump, or the carbon brush is too tight. Rick lived and waited. The unit's running speed is reduced or the vibration is improved, and the spark will be reduced.

3. Chemical factors:

The unit is operated in a corrosive gas, or the operating space of the unit lacks oxygen. A layer of naturally formed copper oxide film on the surface of the commutator in contact with the carbon brush is destroyed, and the already formed, approximately linear resistance is reversed. No longer exists, the commutator spark is intensified during the re-formation of the oxide film on the contact surface. The commutator (or slip ring) is corroded by acid gases or grease. Carbon brushes and commutators are contaminated.

Carbon brush maintenance

A. Operation check: Strengthen the inspection of regular and irregular equipment. Under normal circumstances, the staff must check the generator carbon brush twice a day (once in the morning, once in the afternoon), and measure the collector ring with an infrared thermometer. The temperature measurement interval should be shortened when the temperature of the carbon brush, the peak load during the summer, and the fluctuation of reactive power and voltage are large, and the replacement of the new carbon brush should be checked. Conditional units should periodically measure the temperature of the collector ring and carbon brush with an infrared camera. And do a good job of patrolling inspection equipment operating conditions record.

B. Overhaul and replacement: Accept the newly purchased carbon brushes. Determine the inherent resistance of the carbon brush and measure the contact resistance of the carbon brush lead. The resistance should meet the manufacturer's and national standards. Strictly grasp the process of replacing the carbon brush. The carbon brushes used in the same unit must be consistent and should not be used. Before replacing the carbon brush, carefully grind the carbon brush to make it smooth. The brush should have a gap of 0.20.4 mm in the brush holder, and move freely up and down in the brush holder.

C, daily maintenance: diligent cleaning, soot blowing, keep the carbon brush and commutator slip ring smooth, in case of windy weather, or must be cleaned in time. The spring pressure is adjusted frequently, and the pressure of the carbon brush spring is in accordance with the manufacturer's specifications, so that the carbon brush is subjected to uniform pressure. Prevent individual carbon brushes from overheating or sparking, and burnt burns. Problems in the operation of carbon brushes must be eliminated in time to avoid vicious cycles and endanger the normal operation of the unit.

The carbon brushes used in the same unit must be identical and must not be used in combination. For maintenance personnel, be careful when checking maintenance. The bun should be placed in the cap and fasten the cuffs so that the clothes and wiping materials are not caught by the machine. When standing during the work, do not touch the two poles or one pole and the grounding part at the same time, nor can two people work at the same time. When adjusting and cleaning the carbon brush and slip ring on the rotating motor, it must be carried out by comrades with practical experience.