997-532-000-1, Issue 1
March 2006
12
EN54 & ISO 7240 2-8 Zone Conventional Fire Panel - Installation & Configuration Manual
3.3
EMC Considerations
Following the above instructions and by using suitable
screened cables EMC problems will be avoided.
In particularly difficult EMC environments, or where non-
preferred cabling is used, it is possible to fit ferrite sleeves
to cables entering the panel, in particular the power
supply input, sounder and auxiliary output cables.
The ferrite sleeves (A) should be fitted over all the
conductor(s) and as close as possible to the entry point
of the cable. If required, use a cable tie (B) - not supplied
- to hold the ferrite in position.
If additional ferrites are required these can be purchased
from your supplier (ZIRCON/EN/SPARES).
3.4
Cables for Sounder Circuits
When designing the sounder circuits, check that you are
using an adequate cable diameter, considering the cable
length, to ensure sounders operate within specification.
Example:
Sounder circuit output:
20.0V (min); 0.5A (max)
Sounder device spec.:
15Vdc (min); 20mA (depends
on tone used)
Cable type spec.:
Pirelli FP200 Gold, 1.5mm
2
core resistance:12.1R/km
(per core at 20°C).
Maximum number of sounders per sounder output
circuit:
= 0.5A / 0.020A = 25
Assuming worst case loading with all sounders at the
end of the cable:
Maximum cable resistance to ensure 15V:
= (20-15) / 0.5 = 10R
Maximum cable length that will ensure 15V minimum:
= 10 / (12.1+ 12.1) = 0.413km
If the sounders are more evenly distributed along the
length of the cable, then calculations will show that longer
cable lengths are permissable. After installation, the
following tests will confirm that your installation is
functional:
a. Activate the sounders and measure the voltage drop
along the cable:
V
drop
= Panel Terminal Voltage - End-of-line Voltage
b. Subtract this from the mimimum terminal voltage
when on battery back up to give the minimum end-
of-line voltage (V
eolmin
):
V
eolmin
= 20 - V
drop
The voltage must exceed the minimum specification of
the sounders, typically 15V.
A
B
Summary of Contents for EN54
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