User's Manual

Fire Alarm Systems | FLM‑I 420‑S Short Circuit Isolator
The Short Circuit Isolator isolates alarm zones in which a
short circuit has occurred. This means the functionality of
the remainder of the network remains preserved.
System Overview
b1+ a- b2+ N/A N/A N/A
LSN
9 1
6 4
7 3
8 2
0
5
8 2
0
5
6 4
9 1
7 3
CL 1
2
0
Description Connector
b1+ / a- / b2+ LSN
N/A (3 x) free terminals, e.g. for looping through ext. auxiliary volt-
age and for shielding
Functions
Features of improved LSN
The interface modules in the 420 series offer all the
features of improved LSN technology:
•
Flexible network structures including T‑tapping
without additional elements
•
Up to 254 LSN-improved elements per loop or stub
line
•
Unshielded cable can be used
Address switch (rotary switch)
The address of the Short Circuit Isolator is set using the
rotary switches.
The following settings are possible:
0 0 0 Loop/stub in LSN mode improved version with automatic
addressing (T-tap system not possible)
0 0 1 - 254 Loop/stub/T-tap system in LSN mode improved version
with manual addressing
CL 0 0 Loop/stub in classic LSN mode
Configuration
The Short Circuit Isolator isolates alarm zones in which a
short circuit has occurred. The following illustrations
show typical configurations of the isolator module.
FLM‑I 420‑S Short Circuit Isolator
▶
Rotary switch for automatic and manual address
setting
▶
Preservation of LSN loop functions in the event of a
short-circuit by two integrated isolators
▶
Power supply via LSN
▶
Three free screw terminals
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