Cable with overall shield for protection from lightning and faults

A study was conducted to device means to prevent or control the effects of lightning on instrument and control systems. It is found that the best approach for lightning protection is to use instrument cables with an overall shield grounded at both ends. The overall shield functions as a magnetic shield. It is not a shield because of the mere presence of metal, but because it generates a counter, or opposition, current into the signal conductor. This counter current cancels out the interference current generated by a lightning stroke or other transients.<
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