NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Clive Sutherland
Date: 2010 Aug 6, 15:23 +0100
Hi
I have just rejoined the list after a long spell and This
is my new message. Things have changed a bit since my last, so this may not go
the way it should. If I get it wrong perhaps someone will put me right.
In response to the (old) thread this may be of interest:-
I have a Journal published by the Institute of Post
Office Electrical Engineers (in the UK), on ‘The Design, Laying and
operation of the Trans-Atlantic Telephone Cable’, which was a joint
effort by UK, Canada and USA sometime in the early 1950s before Telstar.
In the Introduction to the chapter on Power Feed
equipment, it says “the objective of the design of the power plant”
was, amongst several others, to quote:-
“To compensate for earth potential differences of
up to 1000 volts, of either polarity, that may develop between the earths at
Oban (Scotland) and Clarenville (Newfoundland), during the magnetic storms
accompanying the appearance of Sunspots and Aurora Borealis”.
I don’t know what earth voltages were induced during
the use of the TAT cable, but clearly the engineers were anticipating them to
be quite high! (The cable supply was 1950 V negative, wrt earth, supplied from
one end and 1950 V positive from the other).
However, GPS will probably be immune to induced earth
voltage as the ground monitoring stations are unlikely to be linked by cable! But
high earth voltage excursions might well have damaged the Power and telephone
circuits in the USA.
Clive.