Installation and commissioning
DIGIDRIVE
Variable speed drive
36
Réf. 3218 GB - 4.33 / d - 02.02
LEROY-SOMER
3.5.9 - Recommendations in the event of
interference phenomena
Even when the elementary precautions in
paragraph 3.5.5 are rigorously adhered to,
it is possible that in rare cases some
equipment in the installation may be
affected by interference. Generally,
sensitive measurement sensors are the
most likely to be affected.
Experience shows that the most complex
solutions are not necessarily the most
effective and that in the majority of cases,
very simple remedies offer the best results.
The following actions should not all be
undertaken; stop once the phenomenon
has disappeared.
• Check that the elementary precautions in
paragraph 3.5.5 have been adhered to.
• Fitting sensors: isolate from the metal
structure common to the motor.
• Sensor interference suppression.
Measurement sensors are sensitive
elements which can be affected by
interference.
Most problems can be resolved by placing
bypass capacitors (0.1 to 0.5 µF) on the
sensor feedback signals. This solution is
only possible for DC voltage signals (12, 24
or 48V) or AC voltage 50 Hz up to 220V.
• Protection of sensitive equipment.
If the drive has a much higher power rating
than that of the sensitive equipment
connected on the same mains supply, it is
more economical to place an RFI filter on
the power supply of the low-power
equipment power supply than to install an
RFI filter on the drive input. The installation
recommendations are the same: filter near
the device, device earthed using a short
connection, separate the filter input and
output wires.
• Auxiliary cable for the control electronics
shielding.
If these connections are likely to pass
through areas with a high level of
interference, it may be advisable to double
their shielding with an auxiliary cable
connected at both ends. Circulating
currents are then concentrated in this cable
and not in the low-level connection
shielding.
• MC choke
Depending on the drive rating and the
distance between the motor and the drive,
insert and wire up an MC choke between
the motor and the drive as indicated in
section 3.5.7.1.
• RFI filter
Insert and wire up an RFI filter (mains) as
indicated in section 3.5.7.2.
• Shielded motor cable
Between the motor and the drive, use a
shielded cable in line with the
recommendations in section 3.5.7.3.
3.5.10 - Additional information
LEROY-SOMER will offer every assistance
to the systems integrator, installer or user in
providing any additional information which
does not appear in this documentation, in
addition to any technical support in order to
resolve a particular problem.
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