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The reality of generating and transmitting ultrahigh voltage power, Part 1

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1 Author(s)
Hebra, A. ; Vienna Univ. of Technol., Vienna, Austria

While we admire the precision of atomic clocks and GPS satellites, we tend to forget the fundamental tools used in creating civilization. Flash back to the old Egyptians and their primitive yet effective instrumentation for surveys of their fields in the wake of the yearly flooding by the Nile. Or Eratosthenes of Syene's (today's Assuan) measurements of the Earth's circumference with no other tools than a tower and a deep well in which waters reflected the image of the sun on the day of summer solstice. But even in our days of digital instrumentation and ultrahigh voltage power transmission lines, the means of measurement are often right there under your nose. Line workers - for instance - estimate the distance between towers with nothing better than a two-by-four and a squeeze of the hand. Telepathy? No, just the knowledge that the speed of propagation of transversal oscillations in ACSR cables is nearly the same (130 m/s) for all gauge sizes, and that the length of conductor between two support points can be found by counting the seconds between a hearty hit on the cable and the feeling of its reflection in the fingers clamped around the cable. Primitive? Yes, but the method proves its value when it comes to comparative measurements, such as making sure that the spacing of adjacent spans is not exactly equal. As demonstrated later in the article, slightly unequal spacing is afforded to keep resonant cable vibrations from jumping the suspension points and propagating from span to span.

Published in:

Instrumentation & Measurement Magazine, IEEE  (Volume:15 ,  Issue: 2 )