The Design Of Power Equipment's Other Insulation Monitoring Device

As the development of our country's economy, more and more heavy electrical and high-voltage equipments have been applied in many industrial fields, in one hand, it speeds up the economic development step, but in other hand it also increases the harm to the surroundings and other relative devices. For example, due to the increased atmosphere corrosion, the enlarged amount of the power electrical networks, the higher rated voltage levels and other factors, the flashover accidents are often taking place. At the same time, as the country is staging a reform to the power electrical network, and the higher requirement of development of the automation of the electrical power system, consequently, it needs a more precisely power equipment's monitoring system and a more equipment reliability. The device of power equipment's outer insulating monitoring that researched and made by this project, is a higher precision and higher anti-disturb capability device compared with the traditional insulating monitoring ones, use it you can do real-time on-line analysis and on-line monitoring, in addition, it is very easy to install and maintain and easy to use with a good stability and a strong adaptability to the applying surroundings.In this thesis, firstly, the principle of the electric equipments'insulating, characters of micro-current sensors and sensing principle of the leaking current are analyzed. Then the system's general design plan, hardware's design, software's design and the system's reliability design are discussed collectively. In these process, the entire constructions of the monitoring device is expatiated in the general design plan, the object-orient modularization design ideas and layer-distributed system construct method are adopted in the entire hardware design plan and software entire design plan. The system's hardware design includes: the selecting of the micro-current signal transducer, sampling unit of the surroundings'temperature and moisture, micro-control processor unit and communication unit, and the method of subsection folded-lining floating-coordinates displaying is used to increase the sensing precision of the system, the system's software design includes: the programming of the system's outer insulating monitoring device's DSP, the CPLD software design of the power equipment's outer insulating monitoring device and the behind upper computer's software design that based on Windows 2000 operating system. Finally, together with the matching of the above mentioned hardware and software, the power equipment's outer insulating device has been developed, and it is tested in the field for a period of one year, and the one year's monitoring data are analyzed.In addition, in the developing of this device, for increasing the system's sensing precision and stability and reliability, the below measures are adopted:⑴Two stages of transducers are adopted to process the small signal.⑵By referencing large amount of technical documents and a long time test run to verify and revise the analytical results.⑶The design of the monitoring device's EMC system from three classes are made to insure the system's reliability and stability.⑷CPLD is used to improve the system's integral degree and stability instead of the normal logic timing design.⑸The running surroundings of the power equipment's outer insulating monitoring device is researched, and then several error sources in the installing are analyzed, and the relative revise methods are presented, such as the selection and install style of current-cutting ring.The test run and inspecting results have denoted that the researched power equipment's outer insulating monitoring device, no matter from the hardware design or from the software and upper machine's software function design, have reached the requirements of the design. It has a large sensing range (100μA～100.0mA), when the leaking current is larger than 100.0mA , the fore signal transducer will be saturated fast. In the range of 100μA～10.0mA, the error is±10μA; in the range of 10.00mA～100.0mA, the error is less than 1%. The system is easy to operate, simple to install, it has a good stability and reliability.