Practical Tips On Remedying Electromagnetic Compatibility Problems - Siemens SINUMERIK 840C Operator's Manual

01.99
11.4 Practical tips on remedying electromagnetic
compatibility problems
Table 11-2 Tips for fault elimination
Faulty behaviour
Flickering screen characters
or display surface
The information on the CRT
and the background
information have colours
missing over some areas
Sporadic failure
Permanent axis offset
© Siemens AG 1999 All Rights Reserved
SINUMERIK 840C, OEM Version for Windows (BA)
Electromagnetic compatibility (EMC) means the capacity of an electrical unit
to work properly in a given electromagnetic environment without affecting the
environment in a manner which is not acceptable.
Possible cause
Adjacent unit producing a
magnetic field (e.g. transformer,
electric motor)
Magnetic field of an adjacent
permanent magnet
• Contactors not connected
• Adjacent machines producing
sparks (welding sets)
• Radio transmitter, centralized
multi-station control system
• Cable with wrong screen
connection, cable with wrong
wire combinations or wrong
characteristics
• Interruption in cable
screening (e.g. if a cable
distributor is interposed)
• Bonding conductor laid
wrongly
• Control dirty
See possible causes as for
'Sporadic failure'.
Elimination of fault
Increase distance between CRT and
source fault (>300 mm). In extreme
cases, shield CRT with
MUMETALL.
Remove cause of fault and screen
with MUMETALL.
Note: Effect on screen will only
disappear a few days after removal
of the cause.
• Connect contactors (coils)
• Lay cable to the control
differently (increase distance to
cause of fault)
• Additional screening
• Use original cable and check
core assignment
• Connection of cable
screening, screening the point of
interruption (e.g. the cable
distributor)
• Re-lay bonding conductor
• Clean control (and modules) and
ensure that cleaner air is supplied
See elimination of fault as for
'Sporadic failure'. The actual value
cable acts as the fault sink.
6FC5198-6AA60-0BP1
11 Maintenance
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