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The Origin of Nordic Bridge Structures
The Viking approach to infrastructure and bridge construction was characterized by innovation and practicality suited to their environment and resources. Vikings prioritized durable structures that facilitated trade, travel, and expansion across Scandinavia and beyond. The Arkadiko Bridge, dating from the 13th century BC, in the Peloponnese is one of the oldest arch bridges in existence and use. Neolithic people also built a form of boardwalk across marshes; examples of such bridges include the Sweet. ABSTRACT: This paper is an informal introduction to the theme of bridges, combining the "disciplines" of bridge engineering, history, and philately. It is an updated brief summary of an earlier publication.
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Permissible operating temperature of busbar joints
The IEC 61439-1 sets the thermal limit in busbars working at the maximum working load. Here, 140°C (which is 105K over the ambient temperature of 35°C) is the upper safe temperature limit. With the aid of a correction factor (k2), the continuous currents specified in the follow-ing table may be adjusted to alternative oper-ating temperatures. A maximum temperature-rise of 55 K for bare (uncoated) Aluminium busbars and conductors (Al-Al joint) shall not exceed, to ensure safety & performance of the solution over a prolonged duration of service. Also attaching excerpts of IEC 61439 Ed.