Vuki (Slovakia)

Příspěvek se zabývá projektem inovativního nákladního podvozku normálního rozchodu pro maximální zatížení 22,5 tuny na nápravu. Rodina podvozků označená NP-X je zaměnitelná za dnes běžně používaný podvozek Y25 a vyznačuje se použitím pryžokovových prvků, kyvných ramen a dalších inovativních prvků. Jeho cílem je reflektovat současné a budoucí požadavky na nákladní dopravu. Příspěvek popisuje současný stav vývoje a výhledy do dalších let grantového projektu.

Systematic and a long-term care has been paid to questions regarding safe operation of electrical equipment, being reflected into new requirements for all their components. Many electrical devices in industrial and building units are apart from so-called expected projected stresses arising from their attribution, exposed to stresses, subjected to their application environments or incident and are seldom considered at the planning stage of the complex. Qualified estimate of their effect on the preservation of operational life and functionality requires a comprehensive analysis of equipment and fixing of conditions of continued use on desired level of reliability and safety. Materials, mainly insulation materials are the most important components of power system. However, currently, we witness contradictory trend of the operational life of cables, being functional under fire conditions. The first is the requirement for increasing temperatures to simulate fire conditions during the test from the initial temperature of 650 °C (IEC60331 in 1970) to today’s early 1040°C (EN50577 still being in the process of proposal) [1]. The second is the evaluation of their dependable operation at normal and limit temperatures that can occur during energy transfer [2].In this paper we want to compare the efficiency of various materials and constructions of cables’ fireproof barriers, ensuring their functionality in the fire, not only in terms of their behaviour in the fire, but also in term of the transmission of energy at high temperatures. In this paper we compare the dielectric parameters after exposure of selected cable types to temperatures above the allowed operating temperatures and fixation of their dielectric changes.

Abstract This report is part of an extensive investigation on thermal and thermooxidative degradation. The results of an analysis of the products formed during degradation of the glycol esters of phthalic, maleic, adipic and sebacic acids are discussed. The experiments were carried out in an apparatus especially devised for this purpose. The specimens were subjected to heat treatment at 200, 250, and 300°C. in a current of air for periods varying between 4 and 200 hr. The degradation products were selectively trapped and analyzed by classical methods and by paper chromatography. Some of the degradation products were determined quantitatively, others only qualitatively. Among the degradation products of all types of the polyesters studied were found the monomers, formaldehyde, acetaldehyde, formic and acetic acids, carbon dioxide, carbon monoxide, water and compounds of the type of hydroxyaldehydes, hydroxyacids, and aldehydic acids, which were not identified closer. Furthermore, among the degradation products of glycol adipate and glycol sebacate acids and aldehydes were found with three and more carbon atoms to the molecules. Benzoic acid is a specific product of the degradation of glycol phthalate, as well as cyclopentanone of glycol adipate. The qualitative composition of the degradation products changes little with change in temperature and duration of the experiment. The change in quantity with these factors is greater. From the quantitative standpoint the main degradation products are the monomers, carbon dioxide, carbon monoxide and water. A mechanism for the degradation is proposed which includes consecutive reactions (hydrolysis, esterification, and ressterification) leading to the formation of free endgroups and monomers on the one hand, and radical reactions of which the products are mainly oxidized substances of the structural units of the polymer, on the other.