Siemens FS20 - Periphery Board (2-loop)

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
Determining the cable capacitance
To determine the cable capacitance the following cable lengths must be added:
● Total loop length
● Length of all stub lines
● Length of all cables to all external alarm indicators
● Length of all cables to external circuits (e.g. fire controls)
Figure 24: Relevant cable lengths to determine the capacitance
Calculating the cable capacitance (Cs)
Cs = l * Cs'
Cs Cable capacitance [nF]
l Total cable length [km]
Cs' Cable capacitance per km [nF/km]
LOOPxA
max. C
LOOPxB