Siemens FS720 - Page 62

Calibrating an FDnet/C
-
NET detector line
Calibration report
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62 | 178
Building Technologies
A6V10210416_j_en_
--
Fire Safety
2018
-
08
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29
Figures and calculation variables
In the following section, you will find the main figures and calculation variables
needed to understand and interpret the calibration report.
Line calibration for lines with a stub topology has a reduced functional scope
as
certain calculation variables cannot be measured.
Figure / calculation
variable
Description
I
quiet
The measured power consumption of a line in an quiescent condition.
I
nom
Calculated nominal power consumption of all devices in an alarm scenario.
I
nom
= I
Line[t1]
+ I
Load compensation non-'
Voice alarm sounder beacon/Voice al. sound.
beacon base
' devices
The nominal power consumption is made up of the measured power consumption
of all 'Voice alarm sounder beacon/Voice al. sound. beacon base' devices on the
line and the calculated compensation value for all non-'Voice alarm sounder
beacon/Voice al. sound. beacon base' devices on the line.
I
max
Calculated maximum power consumption of all devices in an alarm scenario with
a simultaneous cable break directly at the connection terminal or a short-circuit.
I
max
= max(I
cable break at terminal<A,B>
) + I
load compensation non-'
Voice alarm sounder
beacon/Voice al. sound. beacon base
' devices
Information: For the calculation, the system takes the larger measured value for
an assumed cable break on connection terminals A or B.
I
tot
The calculated total power consumption of the line card in an alarm scenario.
R
Line+
The measured line resistance on the plus wire of the line.
R
Line-
The measured line resistance on the minus wire of the line.
∆R
max
The calculated tolerance of the line when faced with a gradual cable break and
thermal drift.
The value reveals how much additional line resistance the line can still withstand
without the individual line devices falling below their required supply voltage in an
alarm scenario and in the worst assumed underlying conditions*.
The following applies for a permitted line: ∆R
max
>0 Ω
U
Device
The measured voltage on an 'Voice alarm sounder beacon/Voice al. sound.
beacon base' line device in the worst assumed underlying conditions*.
* The worst possible underlying conditions include a gradual cable break directly
on one of the line's connection terminals and a maximum assumed thermal drift of
∆T = 10 °C.