Solutions to Common EMC Interference Problems
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6 Solutions to Common EMC Interference Problems
6.1 RCD Malfunction
Select a residual current device (RCD) according to the following requirements:
● The AC drive will generate a certain high‑frequency leakage current during
operation. To avoid malfunction of the RCD, select an RCD with an operating
current of not lower than 100 mA for each AC drive.
● When multiple AC drives connected in parallel share one RCD, the operating
current of the RCD must be not lower than 300 mA.
● Recommended RCD manufacturers are Chint Electric and Schneider.
When an RCD malfunctions, perform troubleshooting according to the following
table.
Table 6–1 Troubleshooting for leakage current
RCD Tripped Possible Cause Solution
RCD tripped
upon power‑
on
immediately
The anti‑interference
performance of the RCD is
poor.
1. Use an RCD of recommended
manufacturers.
2. Use an RCD with higher operating
current.
3. Move the unbalanced load to the front
end of the RCD.
4. If an EMC filter unit is installed,
disconnect the EMC screws.
5. If an EMC filter is installed, disconnect
the EMC filter.
The operating current of
the RCD is too low.
The back end of RCD is
connected with an
unbalanced load.
The to‑ground
capacitance at the front
end of the AC drive is high.
RCD tripped
during
operation
The anti‑interference
performance of the RCD is
poor.
1. Use an RCD of recommended
manufacturers.
2. Install an EMC filter unit or EMC filter.
3. Install a simple filter on the input side
of this product, and wind magnetic
rings on LN and RST cables near the
RCD.
4. Use an RCD with higher rated operating
current.
5. Reduce the carrier frequency properly
without affecting the performance.
6. Use shorter motor cables.
The operating current of
the RCD is too low.
The back end of RCD is
connected with an
unbalanced load.
The to‑ground distributed
capacitance of the motor
cables and motors is too
high.
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