Chapter 4 Technical Information
CLV61x bar code scanner
22 © SICK AG · Germany · All rights reserved · Subject to change without notice 8015592/ZNI9/2017-06-13
Electrical installation
If these conditions are not met, e.g. on devices in a widely distributed system over several
buildings, potential equalization currents may, due to different ground potentials, flow along
the cable shields between the devices, which can lead to hazards.
Remedial Measures
The most common solution to prevent potential equalization currents on cable shields is to
ensure low-impedance and current carrying equipotential bonding. If this is not possible, the
following solution approaches serve as a suggestion.
Important! We expressly advise against opening up the cable shields. Doing this means that the EMC
limit values can no longer be complied with and that the safe operation of the device data
interfaces can no longer be guaranteed.
a) Measures for widely distributed System Installations
On widely distributed system installations with correspondingly large potential differences,
we recommend setting up local islands and connecting them using commercially available
electro-optical signal isolators. This measure achieves a high degree of resistance to elec-
tromagnetic interference while at the same time complying with all the requirements of
EN 60950-1.
The ground loop is isolated by using the electro-optical signal isolator between the islands.
Within the islands, a stable equipotential bonding prevents equalizing currents at the cable
shields.
grounding point 1
Electro-
optical
signal
isolator
Electro-
optical
signal
isolator
PLC
Reading
clock sensor
grounding point 2
CLV61x
shielded electrial cablemetal housing fiber optic cable
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