Compared with the traditional design method, the finite element analysis can simulate the real situation of the parts and get the solution to the problem, which provides a strong guarantee for the design and inspection of the product. In this paper, we consider the use of finite element analysis methods, mainly based on the following considerations: (1) The traditional design only verifies the inner side of the spring working ring, ignoring other parts. The finite element model can get data from any position on the model. (2) During the test and measurement process, due to the limitation of the size of the strain gauge and the quality of the paste used in the test, it is basically only the average value of the stress at the measured point, and the exact value is not obtained. (3) Test measurements may be based on personal experience limitations, only some points of interest are measured, and other possible key points are ignored. (4) Some points in practice are impossible to make actual measurements due to location. Moreover, the test is not easy to measure a large amount of point data, which requires finite element method to supplement.
The finite element calculation model, in which point A is located on the inner side of the spring support ring about 100 mm from the end, and points B and C are respectively located in the middle of the inner side of the spring working ring. The middle working circle uses the SOLID 45 unit of the Brick8 node; 10,656 units, 12,054 nodes. The support ring uses the SOLID92 unit of the Tet10 node, which counts 6680 units and 1952 nodes. A total of 17,336 units, 14008 nodes. Experimental stress measurement of springs Although the finite element analysis method has incomparable advantages, the accuracy of the model also needs to be tested to verify. In order to find the maximum local stress of the ST spring under axial load, the main fatigue point (the inner side of the spring support ring and the inner side of the spring working ring) is analyzed, and the outside of the spring working ring is measured for auxiliary comparison. For specific parts, the loading load is 40, 50, 60 and 88 kN in order. The test used a right angle three-direction strain flower. The calculation and test results analysis, from the above test and finite element calculation comparison, the maximum point of stress appears in the inner side of the spring working ring point B, consistent with the classical theory. In addition, the stress at the point A on the inner side of the spring support ring is also relatively large, and this test is consistent with the results of the finite element analysis. The results of the two tests at point B and point C are not much different from the results of finite element analysis. The relative deviation D is expressed by the following formula: D=ReY-ReSReS For the two points B and C, the maximum value of D appears at point B of 50kN, The value is 4178%. For point A, the difference between the two is relatively large, and the maximum value appears at 60kN (88kN), and its value is 26154%. For point A, the experimental data is smaller than the finite element calculation, which is mainly limited by the experimental means. Due to the size limitations of the strain gauges themselves in the test, it is not possible to measure the position where the stress gradient is large. Therefore, the strain at the inner edge of the support ring cannot be accurately measured, and the maximum value of the finite element calculation is appearing at the inner side of the support ring. The stress values ​​of the two points B and C are basically linearly increasing with the change of the load, while the stress value at point A is greatly changed at 4050kN, and the variation of 5060kN is reduced by half. At 6088kN, the change is basically small. According to the finite element calculation results, when the axial load reaches 56kN, the stress on the inner side of the support ring changes little. Test observations revealed that the spring support ring was in contact with the working ring. The drawing requirement of the spring support ring end and the working ring clearance is 216,714 mm, the finite element calculation setting gap is 5 mm, and the actual measured gap of the test piece used is also about 5 mm. However, due to the ST spring during the machining process, the gap cannot be ensured well. When the gap is large, the spring support ring is in contact with the working ring late, resulting in an increase in the stress inside the spring support ring.
High Voltage Switchgear
The power system deals with voltage above 36KV, is referred as high voltage switchgear. As the voltage level is high the arcing produced during switching operation is also very high. So, special care is to be taken during designing of high voltage switchgear. High voltage circuit breaker, is the main component of HV Switchgear, hence high voltage circuit breaker (CB) should have special features for safe and reliable operation. Faulty tripping and switching operation of high voltage circuit are very rare. Most of the time these circuit breakers remain, at ON condition, and may be operated after a long period of time. So CBs must be reliable enough to ensure safe operation, as when required. High voltage circuit breaker technology has changed radically in the last 15 years. Minimum oil circuit breaker (MOCB), air blast circuit breaker and SF6 circuit breaker are mostly used for high voltage switchgear.
High voltage switchgears are categorized as,
1.Gas insulated indoor type (GIS),
2.Air insulated outdoor type.
Again, outdoor type air insulated circuit breakers are classified as, 1.Dead tank type circuit breaker
2.Live tank type circuit breaker
HV Switchgear
HV Switchgear,Small HV switchgear,Metal HV Switchgear
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