Appendix 2 Common EMC Problems and Solutions
‑151‑
6 Appendix 2 Common EMC Problems and Solutions
6.1 Malfunction of the Residual Current Device (RCD)
If an RCD is needed, select the RCD according to the following requirements:
● The drive may generate DC leakage current in the protective conductor, a B‑type
RCD therefore must be used.
● The drive may generate high‑frequency leakage current during operation. To
prevent malfunction of the RCD, install an RCD with tripping current not lower
than 100 mA for each servo drive.
● When multiple drives connected in parallel share one RCD, select an RCD with
tripping current not lower than 300 mA.
● Recommended RCD manufacturers are Siemens and Schneider.
When malfunction occurs on the RCD, take the following measures.
Table 6–1 Measures against leakage current
Symptom
Possible Cause
Measure
The RCD trips at
the moment of
power‑on.
The anti‑interference
performance of the RCD
is weak.
● It is recommended to use Siemens or
Schneider RCDs.
● It is recommended to use an RCD with
a higher tripping current.
● Move the unbalanced load to the front
end of the RCD.
The tripping current of
the RCD is too low.
An unbalanced load is
connected to the rear
end of the RCD.
The capacitance of the
front end of the servo
drive against the ground
is too high.
The RCD trips
during operation.
The anti‑interference
performance of the RCD
is weak.
● It is recommended to use Siemens or
Schneider RCDs.
● It is recommended to use an RCD with
a higher tripping current.
● Install a simple filter on the input side
of the servo drive and wind magnetic
rings on the LN and RST cables near
the RCD, as shown in “
Figure 6–1
Magnetic ring on the input side
”
on
page 152
.
● Reduce the carrier frequency without
compromising the performance.
● Reduce the length of motor cables.
The tripping current of
the RCD is too low.
An unbalanced load is
connected to the rear
end of the RCD.
The distributed
capacitance of the motor
cable or motor against
the ground is too high.
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