Tadiran Telecom Coral IPx 800 Series, Инструкция по установке и справочник по аппаратной части

Страница: 137 / 400

External Connections
5-11
Pr
otection Devices
5
5.3
Protection Devices
0
.
Lightning and over-voltage arrestors are used to protect the user and the system from
lightning and other electrical hazards that may occur on external circuits connected to
the system.
Any cable that passes through open air, under open ground (i.e.: across parking lots,
fields, road beds, etc.), across a bridge, or along the exterior or under the non-metallic
roof of a building, is exposed to lightning and electrical hazards.
Telephone circuit protection devices fall into two distinct design categories:
„
Primary (lightning) protection devices which limit voltages on a telephone circuit
below levels which do not present a hazard to the user. (
Table 5-2
lists minimum
specifications)
„
Secondary (surge and impulse) protectors that further limit voltages on a
telephone circuit to prevent damage to electronic equipment. (
Table 5-3
lists
minimum specifications)
Primary protection absorbs the major impact of infrequent, but dangerous, catastrophic
surges; while secondary protection suppresses constantly occurring impulses which,
while not dangerous, can cripple valuable, and in many cases, essential
communications facilities.
1 Introduction to Primary and Secondary Protection Devices
Any circuit connected to the Coral system that is exposed to lightning or electrical
hazards must be protected with approved lightning and surge protection devices to
avoid potentially lethal hazards to all users.
Secondary protection devices should be installed on any circuit requiring primary
lightning protection, which connects electrically to an interface of the Coral system.