User guide

Projecting Guidelines
5.6.3 Single Earth Systems – Power Loop
Firstly, consider a Single Earth system for simplicity.
1) All PowerLoop cabling must be shielded
Every segment of the PowerLoop cable has to be protected by a
shield that effectively attenuates the radiated field from the cable.
The shielding is required to avoid radiated emissions and hence
crosstalk from one PowerLoop to any other. Armouring is normally not
considered to be a sufficient shield.
2) Shield must be terminated at one end only
The shield must be terminated close to the BSD-340 PowerLoop
Driver. As the cable forms a full loop, the return path of the cable
shield must not be terminated. No electrical connection to earth must
be made anywhere in the system, i.e. the units must be installed and
galvanically isolated from the chassis.
The termination of the shield will be defined by the site installation, to
a earth terminal in the cabinet or similar.
BSD-340
IE
IE 8
PLA+ 6
PLA- 7
PLB+ 9
PLB- 10
Max 30 cm
3) Maximum permissible non-shielded length of cable - 30 cm
This implies that the internal cabling in a rack or enclosure where the
BSD-340 and / or the Loop Units are installed also needs to be fully
shielded. The requirement includes termination / junction boxes and
all field wiring as well.
System Description, AutroSafe Integrated Fire & Gas Detection System, 116-P-ASAFE-IFG/XE Rev. B, 2005-10-27,
Autronica Fire and Security AS
Page 46