INVT Goodrive350 Series Operation Manual page 302

Goodrive350 IP55 High-ingress Protection Series VFD
to the power ground, and connect the upper computer separately to a ground stud.
3. Try to short the signal reference ground terminal (GND) of the VFD with that of the upper
computer controller to ensure that ground potential of the communication chip on the
control board of the VFD is consistent with that of the communication chip of the upper
computer.
4. Try to short GND of the VFD to its ground terminal (PE).
Try to add a safety capacitor of 0.1 μF on the power terminal of the upper computer
5.
(PLC, HMI, and touch screen). During this process, pay attention to the voltage of the
power supply and the voltage endurance capability of the capacitor. Alternatively, you
can use a magnet ring (Fe-based nanocrystalline magnet rings are recommended). Put
the power L/N line or +/- line of the upper computer through the magnet ring in the same
direction and wind 8 coils around the magnet ring.
7.7.3 Failure to stop and indicator shimmering due to motor cable coupling
Interference phenomenon
1. Unable to stop
In a VFD system where an S terminal is used to control the start and stop, the motor cable and
control cable are arranged in the same cable tray. After the system is started properly, the S
terminal cannot be used to stop the VFD.
2. Indicator shimmering
After the VFD is started, the relay indicator, power distribution box indicator, PLC indicator, and
indication buzzer shimmer, blink, or emit unusual sounds unexpectedly.
Solution
1. Check and ensure that the exception signal cable is arranged 20 cm or farther away
from the motor cable.
Add a safety capacitor of 0.1μF between the digital input terminal (S) and the COM.
2.
3. Connect the digital input terminal (S) that controls the start and stop to other idle digital
input terminals in parallel. For example, if S1 is used to control the start and stop and S4 is
idle, you can try to short connect S1 to S4 in parallel.
Note: If the controller (such as PLC) in the system controls more than 5 VFDs at the same time
through digital input terminals (S), this scheme is not applicable.
7.7.4 Leakage current and interference on RCD
VFDs output high-frequency PWM voltage to drive motors. In this process, the distributed
capacitance between the internal IGBT of a VFD and the heat sink and that between the stator
and rotor of a motor may inevitably cause the VFD to generate high-frequency leakage current
to the ground. A residual current operated protective device (RCD) is used to detect the
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Troubleshooting