SICK CLV69x User Manual

If these conditions are not fulfilled, equipotential bonding currents can flow along the
cable shielding between the devices due to differing ground potentials; this can be dan‐
gerous. This is, for example, possible in cases where there are devices within a widely
distributed system covering several buildings.
Remedial measures
The most common solution to prevent equipotential bonding 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.
NOTICE
We expressly advise against opening up the cable shields. This would mean 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.
Measures for widely distributed system installations
On widely distributed system installations with correspondingly large potential differen‐
ces, the setting up of local islands and connecting them using commercially available
electro-optical signal isolators is recommended. This measure achieves a high degree
of resistance to electromagnetic interference while at the same time complying with all
the requirements of EN 60950-1.
grounding point 1 grounding point 2
Electro-
optical
signal
isolator
Electro-
optical
signal
isolator
e. g. PLC
Power
supply
unit
SICK
device
shielded electrical cablemetal housing
fiber optic cable
Figure 21: Prevention of equipotential bonding currents in the system configuration by the use of
electro-optical signal isolators
The use of electro-optical signal isolators between the islands isolates the ground loop.
Within the islands, a stable equipotential bonding prevents equalizing currents on the
cable shields.
Measures for small system installations
For smaller installations with only slight potential differences, insulated mounting of the
device and of peripheral devices may be a sufficient solution.
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ELECTRICAL INSTALLATION
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O P E R A T I N G I N S T R U C T I O N S | CLV69x 8014396/ZMG8/2017-07-04 | SICK
Subject to change without notice

SICK CLV69x Specifications

General

Brand	SICK
Model	CLV69x
Category	Barcode Reader
Language	English