NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: New inovation in astro navigation?
From: George Huxtable
Date: 2010 Aug 3, 21:40 +0100
From: George Huxtable
Date: 2010 Aug 3, 21:40 +0100
Lu Abel wrote, about effects of a serious solar flare on the early electic telegraph "The Northern Lights are caused by atmospheric ionization, and solar flares significantly increase it, so there are many examples of the Northern Lights being seen below their usual latitudes due to solar flares. But as a graduate electrical engineer, I have a hard time with "shorting out telegraph wires." "Shorting out" requires either wires to stretch enough that they touch, or that the air or insulation separating them suddenly becomes conductive. I can not imagine how a solar flare could cause this to happen. Do you have any reference material on how this solar flare "shorted out telegraph wires?" =================================== I know little about early telegraphy, and have read no authoritative detail about what happened in 1859 or in 1989. But that won't deter me from speculating. I~n early telegraphy, repeaters were required at intervals, which were first human operators, later based on the use of electrical relays. The aim was to maximise the distance between repeating stations. This was done by keying signals using a large voltage at one end, taken from a big stack of batteries, which could amount to some kilovolts, and detecting the resulting current pulses at the other using a sensitive galvanometer. There would be spark gaps placed to protect the galvanometer in the event of a lighning strike. I can envisage a flare producing enhanced ionisation in the air, resulting in sparking at those spark gaps and perhaps elsewhere. I've considered the effect of voltages induced in the current loop created by the wire and its ground return, by changes in the magnetic field passing through that loop, but at first sight the order-of-magnitiude seems quite insufficient to give rise to sparking.. As for the 1989 event that knocked out the Quebec electrical grid, I've seen it ascribed to a runaway event triggered by a burned-out power transformer. But what caused the transformer failure? Such systems are protected against lighning surges, which I would expect to be rather more testing. Or was it a failure of cotrol circuitry? It's possible to imagine sudden changes in Earth's magnetic field giving rise to unexpected current surges in ground-loop circuits, giving rise to a cumulative domino-effect in the protection system. But to be honest, I'm only guessing. Can anyone offer an authoritative study of either event? George. contact George Huxtable, at george@hux.me.uk or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.