Research Of Mechanical Properties Of Circuit Breaker Monitoring And Arc Detection On 12kV Switch Cabinet

With the rapid development of electric power industry, the protective measures of 110 kV and above voltage levels are relatively mature and perfect.However, the bus system in the voltage levels range from 6kV to 35 kV is not configured with fast bus protection generally but depended on the back-up protection of the upper level transformer to remote the bus fault which resulted in the extension of the fault removal time and increased the damage of the equipment. Circuit breaker is one of the most important equipment in power system, which is responsible for the important task of limiting the short-circuit current and improving the reliability of the system. At present, the application of Circuit Breaker on-line monitoring is less. The staff can not understand the health and status of circuit breaker but through regular maintenance to eliminate the trouble which is not only increased the cost of maintenance greatly, but also cause the new fault of circuit breaker. The on-line monitoring of Circuit Breaker can improve the security and reliability of the system effectively. Aiming at the above problems, the paper's main content includes:(1)Introduced the cause and harm of Arc. Based on the energy and spectrum of Arc and research of the detection principle of electric arc. Both overcurrent and arc were adopted to detect the fault of the arc. Selected the appropriate arc sensor, this paper focused on hardware module designer of Arc detection unit.(2)The whole hardware system of the intelligent monitoring unit of Circuit Breaker was designed. We will focused on the hardware circuit design of the sensor acquisition module,signal processing module and CPU control module in the device, which including the selection of components and circuit principle analysis. Designed the software function of intelligent monitoring unit and described the program structure of each module. The mechanicproperties parameters of Circuit Breaker and the HMI displaying module and display software are introduced. Analyzed the criterion of opening-closing of Circuit Breaker and researched the opening time and closing time significantly. Achieved the acquisition of the breaker's mechanic properties and drawed out the travel-time and coil current curve by the mechanic properties, which is used to judge whether the circuit breaker operating mechanism is normal.(3)Through the experiment of the 12 kV circuit breaker, repeated manual circuit breaker closing operation. Observe the change of the mechanic parameters of the circuit breaker on the displaying unit. Analyzed the operating status according to the obtained data and combined whit the waveform curve and the circuit breaker's factory inspection report. Studied the waveform of the circuit breaker in several fault condition and a comparative assessment with the normal coil current. Through the experiment verify the functions and maneuverability of the intelligent monitoring unit in this paper.