Signal Cable Connection - Siemens LDS 6 Operating Instructions Manual

4. Sensor electronics voltage supply connection. 24 V/60 mA.
5. Signal output connections.
6. Network connection. Ethernet 10Base-T (RJ-45).
See also
Pin assignment of LDS 6 (Page 31)
Signal cable connection (Page 29)
3.3.3

Signal cable connection

Signal voltages
The signal voltages must be electrically isolated extra-low voltages (SELV). The maximum
voltage potential accessible to persons is 33 V
voltages are available, then it is possible that the sum of these potentials is higher than that
allowed to get in contact with the human body.
Signal cables
The signal cables must only be connected to devices which guarantee safe isolation from their
power supply.
If signals (i.e. analog output 4-20 mA) are to be routed into a potentially explosive atmosphere
of zone 1, they must be intrinsically safe. Supplementary retrofitting of the analyzer with energy-
limiting modules is necessary.
The Ex identification of these modules must be clearly visible on the housing:
• The signal cables in the rack mount analyzer are connected to the DSUB plugs at the rear.
• RC elements must be connected according to the figure "Spark suppression" below as a
measure to suppress the generation of sparks across the relay contacts (i.e. limit relays). Note
that the RC element results in a drop-out delay for an inductive component (i.e. solenoid
valve). The RC element should therefore be dimensioned according to the following rule-of-
thumb:
R [Ω] ≅ 0.2 x R
Additionally, make sure that you only use a non-polarized capacitor C.
Note
When using direct current, it is possible to fit a spark suppression diode instead of the RC
element.
LDS 6
Operating Instructions, 01/2022, A5E00295894-10
CAUTION
WARNING
[Ω] C [µF] ≅ I
L
or 46,7 V peak or 70 V dc. If several SELV
eff
[A]
L
Installation guidelines
3.3 Electrical connections
29