Development Of The On-line Monitoring Device For Medium Voltage Switchgear With A Magnetic Actuator Circuit Breaker

As the gradual development of our national economy and people’s living standard, the traditional power system network can not meet the needs of economic development and the people’s expectation. Smart grid has been attached great importance from the national strategic aspect as an important initiative enhancing the security and reliability of power system’s operation. In the distribution, on-line monitoring for switchgear, which is the key equipment, can find the potential failures in time and improve the security and reliability of the power system, which has very important significance for intelligent construction of smart grid.In this thesis, according to the national draft standard, combined with one enterprise’s 12kV switchgear with a magnetic actuator circuit breaker, an on-line monitoring device has been developed. The device has the function of monitoring, diagnosis, and communication for the operation condition of the switchgear. It can monitor contact box insulating condition, bus bar temperature rise condition, mechanical properties condition and electric chassis and electric grounding switch motor current states, and potential failures will be detected with the combination of the switchgear’s operation history, then send data to the computer for remote monitoring. In hardware, the device designed each modular circuit board based on theADμC842, and achieved extraction and regulation for the switchgear of the insulation, temperature, mechanical properties, and electric chassis and electric grounding switch motor current. In software, based on the idea of modular programming, by developing the insulation, temperature, breaker and electric chassis and electric grounding switch motor current and communication processing program modules, the on-line monitoring software system is completed.After completing the debugging of each modular circuit board under laboratory conditions, the device and sensors are installed in the enterprise. At the same time, the functions of monitoring, diagnosis, and the device self-checking function and communication function are tested, and performance test all show that the device has reached the national standard and enterprise standard of intelligent switchgear in terms of the its insulation, temperature, mechanical properties and electric chassis and electric grounding switch motor current. Meanwhile, the device has been given the EMC test, which included electrical transient bursts, electrostatic reactance interference immunity test experiment, the surge immunity test, and successfully passed the Level4 test on the basis of many changes and tests, which guarantee the normal operation of the device even under strong electromagnetic interference environment of power system.