32 en | Planning Modular Fire Panel
09.2017 | 11.3 | F.01U.028.089 System Information Bosch Sicherheitssysteme GmbH
q = cable cross section = 0.503mm
2
(for cableØ0.8mm)
n
E
= number of elements
ρ = specific resistance of copper = 0.0178mm
2
/m)
R
FET
= FET resistance = 0.7Ω (LSN classic) or 0.35Ω (LSN improved),
I
NE
= average current consumption of elements in[A]
I
trans
= transmission current = 0.012A
I
flash
= flash current = 0.018A
Note that the sum of non-isolated cables must not exceed the limit of 500m. The limit of
500m applies to:
– The lines on the inputs of the following modules: FLM-420-RHV, FLM-420-I2 , FLM-420-
I8R1-S, FLM-420-O8I2-S, FLM-420-O1I1, FLM-420-RLE-S
– The NAC line of the FLM-420-NAC module
– The lines to remote indicators: FAA-420-RI-DIN, FAA-420-RI-ROW
The limit of 500m non-isolated cables doesn't count for the conventional lines of the
FLM-420/4‑CON and the lines connected to the relay contacts and open collector outputs.
Note that the maximum cable length must not exceed 3000m.
Using the Diagram for LSN improved
FET resistance = 0.35Ω, fire alarm cable with Ø0.8mm
Example 1:
You want to know the maximum cable length for a given number of network elements and a
given current consumption (n
E
=120, IN
E
=0.5mA). On the X axis, go vertically up at 120 until
you reach the 0.5mA curve. Then, from the point of intersection go horizontally to the left to
the Y axis and read off the maximum achievable cable length. In this example it is 1950 m.
Example 2:
You want to know the maximum number of network elements for a given cable length
(L=1000m, I
NE
=2mA). Starting from the Y axis at 1000, go horizontally across to the right as
far as the 2mA curve and then from the point of intersection vertically down to the X axis.
Read off the maximum number of network elements, in this example it is 73.
Notice!
Remote indicators activated by the detector C point:
A maximum additional cable length of 500m is allowed when using remote indicators (e.g.
FAA-420-RI-DIN/FAA-420-RI-ROW).
The total length of installed cable must not exceed the limit of 3000m.