14 Addressable Fire Panel IRIS - Installation and Programming Manual
• Loop Controller “Loop SS”
The maximum length of the loop in the system could vary according to the cross-section and the ohmic resist-
ance of the used cable. To make possible identifying devices with identical addresses (double addresses) in
the system conguration, the cable resistance should not exceed denite calculated value. According to the
ohmic cable resistance, calculate:
· Formula 1: L
C1MAX
= 21 / R
C
· Formula 2: L
C2MAX
= 80 / R
C
,
Where:
L
C1MAX
and L
C2MAX
- are maximum permissible length of the used cable, [km];
R
C
- is total ohmic resistance of the two wires of the used able; its value shows the magnitude of the cable
resistance at length 1km [Ω/km].
If
L
C
is the necessary length of the cable used in the loop, then:
· At L
C
≤ L
C1MAX
- the re pane will be able to communicate with the devices in the circuit and also will
be able to identify the presence of double address.
· At L
C1MAX
< L
C
≤ L
C2MAX
- the re panel will be able to communicate with the devices in the circuit
but will not be able to identify the presence of double addresses.
· At L
C
> L
C2MAX
- the re panel will not be able neither to communicate with the devices nor to identify
the presence of double addresses.
R
C
= 39 Ω/km, then
L
C1MAX
= 21 / R
C
= 21 / 39 ≈ 0,540km
L
C2MAX
= 80 / R
C
= 80 / 39 ≈ 2km
L
C
= 1km
In this case it is possible to use the chosen cable in the system, but the re panel will not be able to identify
devices with double addresses. If this could not satisfying the requirements of the system it must be chosen
cable with lower ohmic resistance R
C
.
• Loop Controller “Loop SS”
The maximum length of the loop in the system could vary according to the cross-section and the ohmic resist-
ance of the used cable.
To ensure the correct operation of the system is necessary to make some calculations in advance:
1. To ensure the ability of the re
panel to receive the signals from the
devices in the loop, calculate:
L
C1max
≤ 123 / R
C
2. To ensure the ability of the re
panel to recognize the double ad-
dresses in the system, calculate:
L
C2max
≤ 62 / R
C
3. To ensure the ability of the devices
in the loop to receive command sig-
nals from the panel, calculate:
L
C3max
≤ (12 / I
max
- R
i
)
/ R
C
Where:
L
C1MAX
, L
C2MAX
and L
C3MAX
- are maximum permissible length of the used cable, [km];
R
C
- is total ohmic resistance of the two wires of the used able; its value shows the magnitude of the cable
resistance at length 1km [Ω/km];
R
I
- is the total resistance of the isolator modules in the loop;
I
max
- is the maximum current consumption in the loop - total amount of the current consumption of all devices
in the loop.
( In case of using addressable base IRIS ligth B24A, the total amount for I
includes: the maximal current con-
sumption in alarm mode of 15 devices with base IRIS ligth B24A, and for the rest of the devices with base IRIS ligth
B24A - the total consumption in stand-by mode.)
L
C
is the necessary length of the cable for the loop.
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