The Design Of Controlling Device For Outdoor Vacuum Circuit Breaker With Monostable Permanent Magnetic Mechanism

10 k V feeding line occupies a considerable proportion in the distribution network and fuses or demarcation load switch are used for protection and control in the T contact between users and power supply company. However, it is difficult for them to isolate fault users quickly without affecting normal power users. With the development of all kinds of vacuum circuit breaker with permanent magnetic mechanism, it reflects advantages and it has also been used gradually in the field of medium-voltage. The complete set of corresponding controlling devices is developed which is applied to the T contact of the 10 k V feeding line, so that it can monitor the running state, distinguish fault types of users and eliminate the transient fault.Firstly, the paper introduces the basic working principle of vacuum circuit breaker with monostable permanent magnetic mechanism and the grounding mode of the 10 k V distribution network. And it focuses on the analysis of the steady-state characteristics of phase-to-ground fault. Besides, it also introduces the principle of extracting fault characteristic quantities by using fast Fourier transformation(FFT) to make theoretical preparation for protective relaying function of controlling device.Secondly, the paper introduces the overall design scheme of the controlling device. According to the function, the controlling device is divided into primary control unit, power management unit and human-computer interaction and communication unit, which using microprocessor of STM32 series as their control chip. Features of the hardware design as follows:1) The controlling device is installed in the outdoor and there is not power, so the output voltage of potential transformer secondary act as the main power supply with the backup power of lead-acid battery, achieving the uninterrupted power supply by the electric power supply plan above. 2) Opening or closing operation need large current to drive, so the controlling device uses the 22000μF capacitor as the power supply for opening or closing operation which can release short-term large power by the full bridge circuit in order to drive opening or closing operation of monostable permanent magnetic mechanism. The paper mainly introduces the transplantation process of the real-time operating system μC/OS-II and main flow charts of each part of controlling device.Finally, I set up the experiment platform in the laboratory to verify the function of measure, control and protection through performing experiments. At the same time, the pulse width of the drive signal is determined to ensure the operation reliability of opening or closing of permanent magnetic mechanism. The experimental data of controlling device is gained and it is within the error range, and the protective relaying action is also fast, reliable and selective. It has reached the design target.