Siemens FS20 - Line Separation Function

Planning detector lines
Planning an FDnet detector line
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Building Technologies
008843_v_en_
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Fire Safety
2015
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12
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15
Technical specifications
● All FDnet devices have an integrated ↑ line separator.
● Only one ↑ stub may branch off between two adjacent devices.
● When there are several stubs next to one another, a line separator FDCL221
must be connected between each one.
Maximum number of stubs/sub-stubs on loop:
Max. number of
stubs/sub-stubs on loop
Loop resistance
R
cable
+ R
iso
Pure cable resistance
R
cable
5 <240 Ω <180 Ω
10 <210 Ω <150 Ω
20 <150 Ω <100 Ω
40 <100 Ω <60 Ω
Table 15: Number of sub-stubs depends on line resistance
R
cable
: Pure cable resistance of loop (measured on the loop terminal)
R
iso
: Total of isolating resistors of line devices on loop (0.5 Ω per line device)
7.1.5 Line separation function
All FDnet devices have an integrated ↑ line separator.
It has two functions:
● Short-circuit and open line monitoring
● Allows branching of a stub between two FDnet devices
Short-circuit monitoring
In the case of a short-circuit on the ↑ detector line, the ↑ line separator
automatically isolates the faulty line section. This is to ensure that, in the case of a
short-circuit, only the faulty line section fails, not the complete detector line.
Open line
If the detector line is a ↑ loop, no devices fail in the case of open line.