Lighting Protection For Antenna & Feeder Subsystem - Huawei Airbridge BTS3612A-1900 Technical Manual

Technical Manual
Airbridge BTS3612A CDMA Base Station
Figure 6-1 Connection to BTS via trunk cables
All E1 cables achieve the lightning protection through the E1 lightning protection board.
The circuits on the board can prevent the lightning current going into the cabinet
through E1/T1 cables when the trunk lines get lightning stroke, and the circuits can also
discharge most of the current through the electricity discharge tube when large current
strikes the cabinet.
6.2.4 Lighting Protection for Antenna & Feeder Subsystem
The Radio Frequency (RF) equipment of the BTS shall be placed within the protection
range of the lightning rod, which is the precondition to ensure the normal performance
of BTS lightning protection system.
I. Lightning protection for RF antenna & feeder
The lightning protection function for the antenna & feeder protects the equipment
against secondary lightning attack, i.e. the inductive lightning. Inductive lightning
means that the feeder receives inductive current upon a lightning attack, which may
cause damage to the equipment.
Inductive lightning can be prevented effectively in three ways:
The feeder is grounded at least at three points. In actual implementation, the
number of grounding points depends on the length of the feeder.
For 450MHz band and 800MHz band, the RF antenna & feeder part and CDU (or
DDU, DFU) are grounded through an internal path. The lightning current induced
by the antenna & feeder can be directly discharged to the ground through the
grounding point. In addition, the CDU (or DDU, DFU) itself features strong
protection capability against lightning current, and can satisfy the normal
protection requirements without extra lightning protectors.
BTS
75/120/100
Transmission
equipment
Grounding bar
Chapter 6 Lightning Protection and Grounding
75/120/100
BESP
BCIM
6-3
System Principle