METHODS OF QUALIFYING ELECTRICAL CABINETSFOR THE LOAD CASE EARTHQUAKE

摘要

With the qualification of electrical system cabinets for the load case earthquake it is differentiated betweenthe two objectives a) stability of the cabinet and b) functionality of the built-in electrical modules during andafter the earthquake. There are three methods to attain these goals: analyses, tests and proof by analogy.A common method is the shaking of a complete cabinet on a shaking table, with the advantage that stabilityand functionality can be proved at the same time, but with the disadvantage that quite expensive test equipment,especially a multi-axle shaking table, is necessary and that generally a cabinet which was proved for SSE is preaffectedand thus may not be incorporated into the plant offhand, I. E. the extreme example would be that thecabinet must be built twice.As a rule, analyses are currently carried out by means of Finite-Element-Models of the supporting structurewith consideration of the electrical components at least with their masses. This analysis can prove the stabilityand pursue the excitation until the anchoring point of the electrical components (Henkel et al., 1987). Thecombination of the aforementioned two methods often constitutes the best way. The stability of the cabinet isproved by calculations, the functionality of the safety-relevant modules by tests. Once tested, modules identicalin construction can be used for cabinets without further testing for earthquakes of similar or lower levels.Proof by analogy is possible only if tests or analyses of similar cabinets were done in advance. By means ofthe comparison of supporting structure, mass allocation and distribution, level and shape of the earthquakeexcitation it can be shown that the cabinet planned is covered by cabinets already tested or analysed (Katona etal., 1995). All facets of the various methods with advantages and disadvantages are discussed and explained onthe basis of numerous examples.