Technical Information Chapter 4
RFU63x
Electrical installation
8014335/YUO7/2016-04-04 © SICK AG · Germany · All rights reserved · Subject to change without notice 41
4.6 Prerequisites for the safe operation of the RFU630 in
asystem
The RFU630 is designed and tested for electrical safety according to EN 60950-1: 2006-
04/A1: 2010-03/A11: 2009-03/A12: 2011-02. It is connected to the peripheral devices
(power supply, clock reading pulse sensor(s), PLC, Host etc.) via shielded cables. The cable
shield, for example, for the data cable rests against the metal housing of the RFU630. The
device can either be grounded through the cable shield or through one of the blind hole
threads on the rear side.
If the peripheral devices have metal housings and if the cable shields also lie on their hous-
ings, it is assumed that all devices involved in the installation have the same ground poten-
tial.
This is achieved for instance by complying with the following conditions:
Mounting the devices on conductive metal surfaces
Correctly grounding the devices/metal surfaces in the system
If necessary, low-impedance and current carrying equipotential bonding between areas
with different ground potentials.
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.
Risk of injury/risk of damage via electrical current!
Potential equalization currents between the RFU630 and other grounded devices in the
system can have the following effects:
Dangerous voltages on the metal housing of the RFU630, for instance
Incorrect function or irreparable damage to the devices
Damage/irreparable damage of the cable shield due to heating and cable fires
Where local conditions are unfavorable and thus do not meet conditions for a safe
earthing method (same ground potential at all grounding points), take measures in
accordance with the following explanations.
RFU630
closed current loop
with equalizing currents
via cable shield
grounding point 2
grounding point 1
grounding potential difference
PLC
Reading clock
sensor
I
U
CDB650-
204
= metal housing = plastic housing
= shielded electrical cable
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