Emc Considerations; Cables For Sounder Circuits - Zircon EN54 Installation & Configuration Manual

EN54 & ISO 7240 2-8 Zone Conventional Fire Panel - Installation & Configuration Manual
997-532-000-1, Issue 1
March 2006
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
A
to cables entering the panel, in particular the power
supply input, sounder and auxiliary output cables.
B
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:
Sounder device spec.:
Cable type spec.:
Maximum number of sounders per sounder output
Assuming worst case loading with all sounders at the
end of the cable:
Maximum cable resistance to ensure 15V:
Maximum cable length that will ensure 15V minimum:
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
b. Subtract this from the mimimum terminal voltage
when on battery back up to give the minimum end-
of-line voltage (V
V
eolmin
The voltage must exceed the minimum specification of
the sounders, typically 15V.
12
20.0V (min); 0.5A (max)
15Vdc (min); 20mA (depends
on tone used)
Pirelli FP200 Gold, 1.5mm
core resistance:12.1R/km
(per core at 20°C).
circuit:
= 0.5A / 0.020A = 25
= (20-15) / 0.5 = 10R
= 10 / (12.1+ 12.1) = 0.413km
= Panel Terminal Voltage - End-of-line Voltage
):
eolmin
= 20 - V
drop
2