某水轮发电机组碳刷温度分布和温升特性分析

Analysis of Carbon Brushes Temperature Distribution and Temperature Rise Characteristic of Hydroelectric Generating Unit

为通过了解温度分布和温升规律来解决碳刷打火问题,利用红外热像仪测量分析了正常碳刷和打火碳刷在相同条件下的温度数值、温度分布和温升曲线,并根据实测数据建立数学模型,分析励磁电流对碳刷温升规律的影响,以计算机组安全运行条件。结果表明,打火碳刷沿滑环旋转方向与滑环的接触面上温度较高,且与碳刷本体温差大,而正常碳刷温度分布较均匀;随励磁电流的增加,打火碳刷温升较快,而正常碳刷温升平稳;打火碳刷与滑环的接触电阻较大且随着励磁电流的增加而波动,碳刷打火伴随着温度的异常升高,且碳刷温度分布不均匀;正常运行时应将打火机组的励磁电流控制在800A以下。

In order to solve the problem of carbon brush sparking through understanding the temperature distribution and temperature rise characteristic, the infrared images of the normal carbon brush and sparking carbon brush were got by an infrared thermal imager under the same conditions. The temperature values, temperature distribution and temperature rise curve were analyzed from the infrared images. Based on the measured temperature rise data of carbon brush, the mathematical model was established to analyze the influence of the excitation current on the law of temperature rise. The safe operating conditions of the unit was analyzed by the mathematical model. The results show that the higher temperature was measured at the carbon brush contact surface along the slip ring rotation direction, and the temperature of contact surface is higher than that of the carbon brush body; But the temperature of the normal carbon brush distributes uniform. The temperature rise of sparking carbon brush is faster while that of the normal carbon brush is stable when the excitation current increases. The contact resistance of sparking carbon brushes between the carbon brush and the slip ring is larger and fluctuates with the excitation current increasing; The carbon brush sparking is accompanied by abnormal temperature rise, and the temperature distribution of the sparking carbon brush is not uniform. The excitation current of the sparking unit should be controlled below 800A during normal operation.