n
Ensure that grounding measures are implemented effectively. The
controllers are grounded to provide protection and for functional
reasons.
n
Provide a star-shaped connection between the plant, cabinets/
cubicles and the grounding/ protection system. In this way you
can avoid ground loops.
n
Where potential differences exist, you must install sufficiently
large equipotent bonding conductors between the different parts
of the plant.
4.2 EMC-equitable assembly
Mostly, measures for suppressing interference voltages are only
taken, when the control is already in commission and the perfect
receive of a wanted signal is disturbed. Causes for such interferen-
ce's are in the most cases inadequate reference potentials, coming
from mistakes at the device assembly and installation.
When assembling the devices, you have to ensure the large-surface
grounding of the inactive metal parts. A correctly done grounding sup-
ports an unambiguous reference potential for the control and reduces
the impact of coupled interferences.
Grounding means the conducting connection of all inactive metal
parts. The sum of all interconnected inactive parts is called ground.
Inactive parts are all conductive parts electrically separated from all
active parts by means of a basic isolation and that may only get
voltage in case of an error.
The ground must not adopt dangerous contact voltage even in case
of an error. Thus you have to connect the ground with the protected
earth conductor. To avoid ground loops, local distant ground con-
structions (cubicles, construction and machine parts) have to be con-
nected with the protected earth conductor system in star-topology.
Please regard at grounding:
n
Connect the inactive metal parts as carefully as the active ones.
n
Take care of impedance-low metal-metal-connections, e.g. with
large-surface and well conductive contacts.
n
If you include coated or anodized metal parts in the grounding,
you have to come through the isolating protection layers. For this
you may use special contact washers or remove the isolation
layer.
n
Protect the connection points from corrosion, e.g. with grease.
n
Moveable grounding parts (e.g. cubicle doors) have to be con-
nected via flexible ground strips. The ground strips should be
short and have a large surface, because the surface is decisive
for the diversion of high frequency interferences.
4.3 EMC-equitable cabling
Content of this section is the line routing of bus, signal and supply
lines. Object of the line routing is to suppress the "slurring" at parallel
lines.
Guidelines for assem-
bling and grounding of
inactive metal parts
Line routing
VIPA HMI Touch Panel
Installation Guidelines
EMC-equitable cabling
HB160 | TP-ECO | 62P-NHC0 | GB | 13-45
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