The application of surge-protective devices in lowvoltage systems faces the dilemma of providing effective limiting against surges while not attempting to limit the temporary overvoltages that do occur in a power system The paper illustrates this dilemma with specific scenarios and presents recommendations for reconciling these two conditions through adequate design and more explicit standards.

In his article "Possibilities and Limits of Comparative Literature Today" Darío Villanueva discusses the itinerary of comparative literature and its problematics and queries the discipline's adherence to literary history and its identification with the theory of literature. Villanueva's discussion is with particular reference to Spanish-language works such as by Claudio Guillén's systemic view ...

surge is one of the two destructive factors in compressors. surge is the stream instability phenomenon in compressor that imposes severe damages to the compressors. nowadays, suppressingsurge phenomenon is one of the most important issues in oil and gas industries, especially when flow reduction or gas reflux is considered. according to moore-greitzer compressor model, this paper designs an act...

Mathematical and simulation models enable hydroelectric power unit dynamic behavior analysis using computers. In this paper, nonlinear mathematical of all elements in hydroelectrical plant are detailed described. Basic water supply tunnel, surge tank, penstock, turbine synchronous generator. If we want more credible simulations calculation results, have to use differential equations. Using thes...

The surrounding rock stability of an underground cavern group is important issue in the process excavation, which has characteristics large displacement, discontinuity and uneven deformation, so calculation analysis are very complicated. optimized discontinuous deformation for failure method was adopted to analyze a real engineering under different excavation schemes. cracking schemes, depth cr...