ZX Fire Alarm Control Panels
Page 24
Document No. 996-174-000-1, Revision: 01
Installation Manual
3.4.9.3 EMC
Compliance
Absorber
Affix cable tie
around wires
below ferrite
Connect Earth drain
wire of cables to nearest
earth stud on inner, top
wall of back box
- keep length
as short as possible
For EMC Compliance, fit
the Ferrite Absorber
supplied with the RS485
Interface board around the
Peripheral (or Panel) Link
cables.
Using crimp rings terminate
the cable screens at the
nearest earth stud on the
inner top surface of the
back box. In order to keep
the earth tails as short as
possible, use an M5 nut to
space the tail crimp rings
from the back box and to
achieve adequate earth
bonding.
The figure opposite shows
the typical arrangement for
a typical installation.
Figure 23 – RS485 Loop – EMC Absorber Installation
3.4.9.4
Cable Screen – Earth Connections
During installation of a panel network the consequences of connecting remote grounds together
must be considered.
When wiring between RS485 cards and/or peripherals if a drain earth wire is available it should
not be bonded to the chassis at both ends of the link.
The drain earth wire
should only be bonded
to one of the panel
back boxes at the
cable gland or
provided earth studs.
The other end should
not be bonded directly
to the back box but
should be connected
through a non-
polarised
2.2µFcapacitor.
Capacitor
Absorber
Absorber
Connect Earth drain
wire of cables to nearest
earth stud on inner, top
wall of back box
- keep length
as short as
possible
This arrangement is
shown opposite.
Figure 24 – RS485 Screen – Earth Arrangement
3.4.10 High Integrity Loop
Hi485 Interface Modules can be used to create a ‘High Integrity’ RS485 Communications Loop
for use on the Panel Network and Peripheral interface links.
The ‘High Integrity’ Loop provides open and short circuit protection to ensure that information can
still be passed around the loop if a single fault occurs. The loop can be extended to provide a
communications network of up to 12km (39000’) in distance.
Refer to the Hi485 Installation Guide (996-065) for further information.
