Bosch FAS-420-TM Operation Manual page 56

56 en | Planning
where
I
g
I
A
I
Q
I
PSmax
I
L
K
n
n
n
max
NOTICE!
The power supply units are laid out using the calculated total current I
Please refer to Section 2.8 Technical Specifications, page 30 for the current consumption of the
FAS-420-TM.
Line calculation
The maximum line length is derived from the permissible voltage drop on the supply line. The
permissible voltage drop is the difference between the end-point voltage of the backup
battery (21.5 V) and the lower operating voltage limits of the aspirating smoke detectors.
where
L
max
A
I
g
γ
ΔU
To guarantee the impermeability of the housing, the corresponding cable bushing must be
selected for the existing cable:
–
–
F.01U.088.878 | 4.1 | 2010.11
= Total current of all connected aspirating smoke detectors in [A]
= Alarm current of an aspirating smoke detector in [A]
= Standby current of an aspirating smoke detector in [A]
= Max. power supply of the network power supply in [A]
= Charging current of the rechargeable batteries (80% of the nominal
capacity within 24 hours) in [A]
= Rated capacity of the rechargeable battery in [Ah]
= Total number of connected aspirating smoke detectors
= The highest number of aspirating smoke detectors in one detection zone
= Maximum line length in [m]
= Strand cross-section in [mm²]
= Total current of all connected aspirating smoke detectors in [A]
= Conductivity: Cu=57 m/Ω mm²
= Charging current of the rechargeable batteries (80% of the nominal
capacity within 24 hours) in [A]
M 25 cable bushing: ∅ 9-14 mm
M 20 cable bushing: ∅ 8-12 mm
Operation Guide
.
I I n I I
+
=
g
Q L
γ
ΔU A
. .
L
=
max
I 2
.
g
FAS-420-TM Aspirating Smoke Detector
PS max
with the highest value.
g
Bosch Sicherheitssysteme GmbH