Emc (Electromagnetic Compatibility); Figure 4-4 Removing The Internal Emc Filter And Line To Ground Varistors - Emerson Digitax ST User Manual

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4.10

EMC (Electromagnetic compatibility)

4.10.1 Internal EMC filter
It is recommended that the internal EMC filter is kept in place unless
there is a specific reason for removing it.
Special attention is required when using a DST120X model on an
ungrounded supply (IT supply). In the event of a ground fault in the
motor circuit the drive may not trip and the filter could be overstressed.
In this case, either the filter must be removed or additional independent
motor ground fault protection must be provided.
The internal EMC filter reduces radio-frequency emissions into the line
power supply. Where the motor cable is short, it permits the
requirements of EN 61800-3:2004 to be met for the second environment.
For longer motor cables, the filter continues to provide a useful reduction
in emission level, and when used with any length of shielded cable up to
the limit for the drive, it is unlikely that nearby industrial equipment will be
disturbed. It is recommended that the filter be used in all applications
unless the ground leakage current is unacceptable or the above
conditions are true.
The supply must be disconnected before removing the
internal EMC filter or line to ground varistor screws.
WARNING
Figure 4-4 Removing the internal EMC filter and line to ground
varistors
2
1
1. Internal EMC filter. Remove the bottom screw as shown.
2. Line to ground varistors. Remove the top screw as shown.
NOTE
The line to ground varistors should only be removed in special
circumstances.
4.10.2 Further EMC precautions
Further EMC precautions are required if more stringent EMC emission
requirements apply:
• Operation in the first environment of EN 61800-3:2004
• Conformity to the generic emission standards
• Equipment which is sensitive to electrical interference operating
nearby
In this case it is necessary to use:
• The optional external EMC filter
• A shielded motor cable, with shield clamped to the grounded metal
panel
• A shielded control cable, with shield clamped to the grounded metal
panel via the grounding bracket.
NOTE
It is not necessary to remove the external EMC filter when using an IT
supply.
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