Characteristic Calculation Lw8b The-40.5kvsf6 High Voltage Circuit Breaker Actuator Breaking Porcelain Breakage Of The Diagnosis

This paper is finished on the basis of diagnosis for cracking of insulated porcelain-mantle equipped with LW8-40.5 (B)-Outdoor H.V SF6 Circuit Breakers manufactured by Yunnan Switches Factory. The interrupting performance of CT14 spring operating mechanism of this kind of breakers and assemble craft of the insulated porcelain-mantle have been studied and analyzed successively as two key clues to inspect the causes, and some interrelated reasons for failure are gained and validated successfully. Meanwhile, corresponding improvement projects and guard points are put forward according to related calculations and analysis on the most possible processes from manufacture to assemblage.The valid project to diagnose the causes for insulated porcelain-mantle cracking has been explored in this thesis, and it will have stronger reference value for practical design and application.Firstly, instantaneous opening/closing speed/work formulas have been deduced and revised according to relevant references for single pressure puffer-type SF6 circuit breakers with rated current, and related parameters and their meanings involved are clarified as well. ADAMS (Automatic Dynamic Analysis of Mechanical Systems) is used to get the average speed of main parts of CT14 spring operating mechanism in interrupting processes to calculate the speed ratio, and UG (Unigraphics) is adopted to get quantity and inertia of relevant parts of this mechanism, and equivalent quantity can be calculated through such over two steps. Compared with traditional methods for calculating equivalent quantity, the result is more accurate but the calculation process is simplified greatly. The final comparison is as fellows:computed opening speed VS design opening speed: Vgf=3.44(m/s) VS Vgf= 3.4±0.2(m/s); computed closing speed VS design closing speed:Vgf=3.8O(m/s) VS Vgf=3.0±0.2(m/s). The comparison shows that the design parameters are reasonable and the methods and approaches adopted in this paper are highly reasonable and creditable. And closing work VS opening work:Wh> Wf (Wh=1861.49(J),Wf=1552.51(J)),such result shows the closing process of mobile electrode is creditable. Secondly, force/moment between conducts and phases and dynamic SF6 pressure characteristics in the arc-chute are computed as another two key points to inspect the cracking causes when short-peak-circuit current is interrupted by this actuator. The result shows that the SF6 pressure and the force\moment produced by short-circuit can not cause insulated porcelain-mantle be cracking.The above process shows that the design of this kind of breakers is reasonable according to calculations and analysis on interrupting performance; Assemble craft of the insulated porcelain-mantle is investigated and analyzed as the next point to find the reason according to investigationg on working spot. Some value result is gained as fellows:the silica gel filled between insulated porcelain-mantle and flange is too excessive which causes excessive screw-moment between flanges be needed to keep seal effect, and such screw-moment leads the insulated porcelain-mantle be cracking.Finally, some effective improvement projects are presented at the end of this paper according to the correlative analysis, and the experiment model and products'working proves that the reasons accord with the failure, and the improvement design is reasonable and valid.