- Enhance the understanding of the oxide film on the brush surface, and establish the conditions for its formation and normal operation: Several recent failures were mainly caused by the inability to form a lubricating layer on the oxide film of the brush surface. The formation of the oxide film requires certain conditions. When these conditions are not met, the oxide film cannot form or forms poorly.
- There are mainly the following reasons:
(1) High temperature: The oxide film on the brush generally forms easily at around 70°C. When the collector ring and the brush have overheating faults, the temperature is usually above 150°C. Even if new brushes are replaced, the oxide film cannot form easily and cannot play a lubricating role. The brush wear will intensify, leading to a further increase in temperature, forming a vicious cycle. At this time, external forced cooling methods can be adopted, such as applying vaseline, using high-power fans for ventilation, etc., to reduce the temperature of the collector ring to a normal range and maintain it for a period of time, allowing the oxide film on the brush surface to gradually form, and entering a benign cycle state.
(2) Pollutants in the cooling air: Impurities in the air will have an adverse effect on the formation of the oxide film on the brush surface. These impurities include: corrosive gases of sulfides or halogens, oil mixtures in the air, dust, iron filings, rust dust, carbon powder and other impurities. When the brush wears, it will produce dust impurities such as carbon powder. A filtering device can be installed on the cooling ventilation circulation channel of the brush frame cover to improve the air quality inside the brush frame cover.
(3) Too low air humidity or too low oxygen content: The formation of the oxide film on the brush surface requires a certain moisture content in the air, that is, the air humidity cannot be too low, but it cannot be too high either. In addition, the formation of the oxide film mainly occurs through oxidation with oxygen in the air. When the oxygen content is too low, it is also not conducive to the formation of the oxide film.
The inability to form or poor formation of the oxide film is not only related to the above factors, but also due to excessive grinding of the brush, using solvents for wiping, poor surface finish of the collector ring, and unqualified carbon brush materials, etc.
2. During the selection of brush and brush frame products, the quality should be strictly controlled: Currently, brushes of the same brand are processed in various different places and factories. This requires us to strictly control the quality during the purchase process and understand the production process and quality inspection methods and procedures of the manufacturers.
3. Strengthen the maintenance and management of collector rings and brushes during production and operation: Strengthen the dedicated maintenance system for brushes and collector rings, improve the technical level of the dedicated personnel, and strictly inspect and maintain the collector rings and brushes in accordance with the requirements of the “Operation Procedures for Steam Turbine Generators”, strictly control the number of replacements of brushes. In addition, actively use infrared thermal imaging technology for daily inspections and checks of collector rings and brushes, and use it as an auxiliary analysis tool when there is suspicion of faults at the fault location.
In addition, this meeting also proposed analysis suggestions for the scaling of the insulation water pipes of the stator:
1. When the insulation water pipes are severely scaled or have affected the results of routine tests, it is recommended to replace all new insulation water pipes.
2. After each major overhaul of the generator, before starting up, the stator water system should be flushed under pressure with demineralized water until the drainage is clear and free of particles and the conductivity is qualified.
3. During normal operation of the generator, when the cumulative operating time reaches two months and there is an opportunity to shut down, the inner and outer water systems of the stator and rotor should be back-flushed.
4. Improve the entire cooling water system of the generator, try to make it a closed circulation system. During operation, if the water quality contains high copper content, the inner wall of the insulation water pipes is dirtied and scaled, the main component is copper, because the waterway is not closed, long-term oxidation and corrosion of the copper tubes cause this.
5. Strengthen the monitoring of water quality during operation, the water quality of the internal cooling system should be strictly implemented according to the operation procedures.
6. For the solution of water system problems, it should mainly start from the daily operation and maintenance, necessary communication and exchange among various specialties should be carried out, and there should be a certain understanding of the cross-knowledge of related specialties. The generator is a comprehensive device that involves many professional aspects. Issues that are considered important in one field might not receive the same level of attention in other fields. This can pose many risks to the safe operation of the equipment.
For more questions about the generator set, please call the Beidou Power team. More than ten years of professional production and sales of power generation equipment experience, more professional engineer team to serve you, choose Beidou power is to choose rest assured, welcome on-site factory inspection.
Post time: Feb-27-2026