3 Installation
35
3.2.3
Power supply and fuse protection
Protect the supply voltage of the safety fieldbox with a 10 A fuse. In order to in-
crease the cable cross section for the supply voltage of the fieldbox, both connec-
tions from Us and GND must be connected in parallel. Pins 1 + 4 and 2 + 3 in the
fieldbox are bridged.
Internal fuse elements device ports
The device ports X0 - X7 are designed for 0.8 A continuous current and equipped
in each case with an auto-resettable fuse of 1.5 A for line protection. If the fuse ele-
ment is triggered, the red LED on the device port flashes with 4 pulses.
After eliminating the overload at one of the device ports, the fuse resets itself after
a short cool-down phase.
3.2.4
Earth concept and shielding
A functional earth is connected for fault-free operation of the safety fieldbox.
Earth loops must be avoided when connecting the functional earth.
The FE functional earth is normally connected via the switch. In the event of EMC
problems, the fieldbox can be earthed via the separate FE connection.
An earth strap is available as an accessory.
Wiring examples for avoidance of earth loops:
FE
SFB
P1
P2
Ethernet
FE
PLC /
Switch
FE
SFB
P1
P2
Ethernet
FE
SFB
P1
P2
Ethernet
FE
PLC /
Switch
FE
SFB
P1
P2
Ethernet