On-site measurement of load and no-load losses of GSU transformer
Present development and production of power transformers with lower losses in addition to replacement of outdated transformers assume regular measurement of losses in both load and no-load regime. These measurements are very demanding especially in the case of on-situ measurements. The complexity of the measurements grows with the size of transformer. This paper presents one typical test of losses measuring in load and no-load regime of power transformer with nominal power of 40 MVA in HPP Perucica.
Limitations of Grundy & Kabaila ’ s simplified method and its repercussion 1 on the safety and serviceability of successively shored building structures 2
10 One of the most critical stages for a structure’s safety is precisely its construction process, 11 and this problem is even more acute in buildings with reinforced concrete structures. These 12 structures are usually built by shoring successive floors, so that the most recently poured floor 13 rests on the lower floors by means of shores. It is therefore vitally important to have calculation 14 tools available to estimate the loads to which the shores and slabs are subjected in each stage 15 of construction. A number of calculation methods have been proposed to date, of which the 16 one proposed by Grundy & Kabaila in 1963 is the best known and most frequently used. This 17 paper analyses the limitations of Grundy & Kabaila’s method by means of a parametric study 18 of FEM simulations, which found a large number of situations in which this method presented 19 unsafe results as regards the estimated loads on the slabs. In many situations, therefore, 20 applying this method could gravely affect a building’s in-service behavior and durability. The 21 paper’s final objectives are to make the reader aware of the limitations of Grundy & Kabaila’s 22 method and the need to use the more refined methods now available to estimate the loads on 23 shores and slabs in reinforced concrete buildings under construction. 24
Study on Electrical Explosion Mechanism and Ignition Characteristics of Copper and Aluminum Powder Under Ignition Solid Propellant
In order to study the characteristic of the electrical explosion of copper and aluminum powders, a multilayer generator was designed, an experimental system was set up, and the parameters of metal powder electrical explosion were measured and analyzed. The results show that the duration of the electrical explosion process increases significantly due to the addition of metal powder. The duration of aluminum powder electrical explosion jet flow is ~86.36 ms due to its self-sustained combustion, which releases a large amount of energy, and a small fraction of aluminum powder particles is not burned. The duration of copper powder electrical explosion jet flow is ~15.84 ms, and most of the copper powder particles are in the solid state. The current pause process is absent; instead, the first discharge process is connected to the second discharge process. The effect of copper powder on the first discharge process is greater than that of aluminum powder. Furthermore, the ignition ability of copper powder electrical explosion to solid propellant is stronger than that of aluminum powder in a closed bomb experiment. These results are indubitably meaningful for the application of metal powder electrical explosion and ignition of solid propellant in an electrothermal chemical gun.