Situation 2
F
CDB/CDM
RFU6xx/RFH6xx
+
+
−
−
+
V
S
−
+
−
1
4
2
2
+
3
−
−
−
F
CDB/CDM
RFU6xx/RFH6xx
+
+
−
−
+
V
S
−
+
−
a
1
4
2
2
3
Figure 35: Reversal of the polarity of the supply voltage with common system GND: Risk of dam‐
age to the RFID device!
1
Fuse in the connection module: 2 A (CDB650-204, CDM420-0006)
2
Blocking diode
3
Connection module
4
Battery
The housing of the RFID device is connected (see figure) in an electrically conductive
manner to the reference potential (system GND), which is also connected to the nega‐
tive pole of the applied supply voltage. Typical mounting location: Vehicle with chassis
as a common reference potential.
If the polarity of the supply voltage is reversed, this can lead to short-circuit currents
between the reversed positive and negative poles!
The fuse in the connection module is not located in the active circuit.
6.8.2
Supply voltage
The voltage supply or power supply unit must satisfy SELV requirements in accordance
with the currently applicable EN 60950-1. (SELV = Safety Extra Low Voltage).
NOTE
UL-certified devices
(see type label) require a SELV/LPS-compliant supply voltage in
accordance with UL/IEC/EN60950-1 or Class 2 according to NEC, UL1310.
NOTE
Required input voltage on connection module
Voltage drops in the supply circuit affect the connection cable from the connection
module to the device (decrease dependent on the length) as well as – to a certain
extent – the connection module itself.
To compensate for this loss when operating the device at the lower end of the supply
range (18 V DC), apply a higher input voltage to the connection module as per the fol‐
lowing table:
The voltage drops for a customer-specific connection or connection module have also
been taken into account.
ELECTRICAL INSTALLATION
6
8014335/ZTL9/2018-10-14 | SICK
O P E R A T I N G I N S T R U C T I O N S | RFU63x, RFU65x
63
Subject to change without notice
