| Gas insulated switchgear is a widely used electrical equipment in power network. Compared with the traditional open type equipment, GIS has many advantages of compact structure, high reliability, strong safety. But because of its structure which is completely closed, once fault occurs, it will affect a large area.Also it is difficult to locate the fault and fast repair, which will bring serious economic losses. Therefore, it is necessary to monitor the state of GIS equipment. According to the similarities and differences of vibration signal generated for GIS discharge faults and mechanical faults, the following work is done:Based on analysis of the existing detection technology, GIS discharge common defect model has been built in the laboratory. This paper obtain the typical spectra by ultrasonic detection method for GIS shell vibration, and analyzes the characteristics of them.This paper makes a theoretical analysis and calculation of vibration signal characteristics of GIS shell, the vibration detection system is constructed based onthe principle of signal measurement. Also the use of the choice of basis, sensor signal processing and acquisition unit and PC software design are described in detail.Based on the vibration detection system, respectively monitoring test of GIS equipment in the laboratory and field conditions are maken, and the results are compared and analyzed in this paper. Conclusion: laboratory experiments, for single-phase GIS, when the contact is good, there is no vibration signal; but once the existence of contact failure, especially when the current is larger when flowing through the contacts, will lead to the rapid increase of vibration signal. Poor contacts, the vibration signal is in 100 Hz baseband signal, and when the contact fault is more serious, it will produce 3 harmonics. While the field test, the vibration of the GIS, the major frequency of vibration signal is 100 Hz, which is consistent with the laboratory test results. |
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