10/6/10 888-2629-200 D-1
WARNING: Disconnect primary power prior to servicing.
Maxiva ULX COFDM Series
Appendix D Lightning Protection Recommendation
D.1 Introduction
What can be done with a 2 million volt pulse pushing 220,000 amps of current into your
transmitting plant? Like the 500 pound gorilla it does what ever it wants to. There is not
much that can be done to protect against a major direct lightning strike. This is called a
significant impulse lightning stroke. It usually lasts less than 100 microseconds and is
most destructive to electronic equipment because it contains huge amounts of high
frequency energy.
Here are some examples of this damage:
• Melted ball and horn gaps.
• Ground straps burned loose.
• H.V. rectifier stacks shorted.
• Massive arc marks in the output circuit of AM transmitters.
• Ball lightning traveling into building on outer conductor of transmission line.
Figure D-1 is a map of the United States that shows the number of lightning days
expected in any year, with Colorado, New Mexico, and Florida leading the list.
Figure D-2 shows the incidents to tall structures. A triggered event is one that happens
because the tower was present. Without the tower the strike would not have occurred.
Figure D-1 Map Showing Lightning Days Per Year
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