D-2 888-2629-200 10/6/10
WARNING: Disconnect primary power prior to servicing.
Maxiva ULX COFDM Series
Figure D-2 Lightning Incidents to Tall Structures
D.2 Environmental Hazards
There are devices and procedures that do offer protection from lessor environmental
hazards than lightning. Some of these anomalies are listed and defined:
1. Over voltage/under voltage (brownout). Where the lines voltage differs from the
nominal RMS for longer than one cycle.
Remedy - Automatic voltage regulators, preferably individual regulators on each
phase. This can only be accomplished when the power feed line is delta or 4/wire wye
connected, See
Figure D-3.
2. Single phasing. This is where one leg of the three phase service is open.
Remedy - Protection afforded by a loss of phase detector. Without protection power
transformers and 3 phase motors over heat.
3. Radio frequency interference (RFI). This is something we must design into all trans-
mitters, however, equipment may be purchased that is susceptible, is not protected,
and may develop problems.
Remedy - RFI filters on the ac lines and control lines are sometimes effective. Some-
times the entire device must be enclosed in an RF free space.
4. Electromagnetic pulse (EMP). This is a interfering signal pulse that enters the system
by magnetic coupling (transformer). Generally caused by lightning.
Number Per Year
Structure Height In Feet
All
Triggered Events
500
1000
1500
2000
Collected
Events
40
30
20
10
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