Cambium PTP 450 series, Руководство пользователя

Страница: 91 / 180

Grounding and lightning protection PTP 450 User Guide
ptp-450 (July 2014)
2-71
Grounding and lightning protection
This section describes the grounding and lightning protection requirements of a PTP 450 installation.
Electro-magnetic discharge (lightning) damage is not covered under warranty. The recommendations in
this guide, when followed correctly, give the user the best protection from the harmful effects of EMD.
However 100% protection is neither implied nor possible.
The need for power surge protection
Structures, equipment and people must be protected against power surges (typically caused by lightning) by
conducting the surge current to ground via a separate preferential solid path. The actual degree of protection
required depends on local conditions and applicable local regulations. Cambium recommends that PTP 450
installation is contracted to a professional installer.
Standards
Full details of lightning protection methods and requirements can be found in the international standards IEC
61024-1 and IEC 61312-1, the U.S. National Electric Code ANSI/NFPA No. 70-1984 or section 54 of the Canadian
Electric Code.
Lightning protection zones
The ‘rolling sphere method’ (
Figure 17 ) is used to determine where it is safe to mount equipment. An imaginary
sphere, typically 50 meters in radius, is rolled over the structure. Where the sphere rests against the ground and a
strike termination device (such as a finial or ground bar), all the space under the sphere is considered to be in the
zone of protection (Zone B). Similarly, where the sphere rests on two finials, the space under the sphere is
considered to be in the zone of protection.
Figure 17 Rolling sphere method to determine the lightning protection zones