Siemens FS20 - Load Resistance Monitoring (Vds)

Defining
controls
Monitored outputs (I/O card (remote transmission) FCI2007
-
A1 and I/O card (horn/monitored) FCI2009
-
A1)
9
137 |
242
Building Technologies
008843_v_en_
--
Fire Safety
2015
-
12
-
15
RIoad Load resistance [Ω]
UIoad Load voltage (Minimum) [V]
RcableMax. Maximum permitted cable resistance [Ω]
Reol Termination resistor [Ω]
Peol Power EOL [W]
9.1.2 Load resistance monitoring (VdS)
The connection type with load resistance monitoring in accordance with ↑ VdS has
the following features:
● Monitoring is only carried out in an inactive status with normal polarity.
If the resistance is not linear and is high (e.g. in the case of electronic loads such
as sounders and beacons), the monitoring resistance must be defined using a
dominant Rx. A freewheeling diode should also be used for inductive loads.
Figure 60: Connection with resistance monitored in accordance with VdS
1
Optional load resistance as well as optional freewheeling diode for inductive load
Planning steps
1. Determine the load resistance that will be connected at the output (Rload),
e.g. sounder DS10: Rload = 24 V/0.42 A = 57.2 ohm
2. Define the minimum required voltage of the sounder (Uload), e.g. datasheet
DS10: U = 19…29 V -> Uload = 19 V
3. In the dimensioning table, find the row that corresponds to these values and
determine the associated values.
The monitored resistance value must be within the range for the monitoring
resistance, otherwise a fault message will be displayed at the ↑ station. You will
find detailed information about this in document Product data 008837.
Dimensioning of load with load resistance monitoring in accordance
with ↑ VdS
Use the dimensioning table to determine the following:
● RcableMax
Example from dimensioning table 1
● For Rload >40 ohm
● RcableMax = 6 ohm
For the Rx and diode, make sure the dimensioning is correct (maximum power
dissipation, maximum diode reverse voltage >30 V, etc.).
-
Rload
FCI2007
FCI2009
Rcable
+
Uload
Rx
1
1