The Current Monitoring System Of Synchronous Generator Excitation Brushes

In order to make sure the sufficient electrical energy is provided by the electric generator, thousands of ampere current flows to the large synchronous generator. According to the relevant data shows, the mechanical sliding flow guiding ring is used between brush and collector ring in the large synchronous generator mostly. There is hidden trouble in this part, because of long time mechanical wear, equipment loss, jitter and other issues. Base on the relevant technical and the requirements of safety production,a method of the excitation current detection for the synchronous motor is proposed. The method of engineering scheme is designed.The characteristics of large synchronous motors are large excitation current, many guide rings, the complex spatial distribution and the interference frequency. In order to measure each road current of excitation brushes accurately. Firstly, the key problem in principle is analyzed. The characteristics of the filter are studied and the filter is used in the excitation brushes current detection. Based on the above analysis and research, the direction of device selections is identified for engineering practice. For the high speed data acquisition of multi-channel current signal, the LTC2494 ADC of LINEAR is controlled by FPGA. At the same time, the 4-20 m A current loop and RS485 are designed to ensure the excitation brushes current monitoring system compatible with mainstream products in industrial control. The Verilog HDL is used in the Modbus communication protocol about the RS485 interface. In the process of programming, the SPI interface, serial port driver and CRC verification and other related procedures are designed through the top-down modular. The program has a good portability.The design of the large synchronous motor excitation brushes current monitoring system is completed through theoretical analysis, device selection and physical production. The system cooperate well with the touch screen of TAIDA B07S411. The on-line excitation brushes current monitoring of the large synchronous motor in the power plant is realized.