Abstract
THE engineers of the staff of the General Electric Co. of America have computed that about 75 per cent of all interruptions to electric service are caused by lightning. In the Electrician of August 4 an account is given of a simple magnetic device which has been largely used for recording the currents that flow in the earth conductors of the lattice towers when the line is struck by lightning. Small pieces of magnetic material called magnetic links are mounted on brackets and installed within a few inches of the leg of the tower. At the present time, more than 2,000 of these links are in use on high voltage lines. The link is so placed and designed that the magnetism induced in it is proportional to the highest value of the lightning current. Line patrolmen working under the research staffs of the power companies test the links periodically for magnetisation. The magnetised links are sent to the research laboratories. By inserting them in a measuring instrument called a ‘surge-crest’ ammeter the pointer of the instrument indicates the maximum value of the lightning current. Currents up to 25,000 amperes have been measured. As the resistance of the ‘earth’ at the tower is sometimes high, this current may be reflected into the service line with ensuing damage or interruption of the power current. The overhead earth wire at present largely used as a safeguard against lightning was the outcome of previous experimental researches on voltages induced by lightning.
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Lightning Current Recorders. Nature 132, 309 (1933). https://doi.org/10.1038/132309a0
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DOI: https://doi.org/10.1038/132309a0