Chapter 5 Troubleshooting VFD-EL-W
171
5-12 Electromagnetic/Induction Noise
Many sources of noise surround AC motor drives and affect them by radiation or conduction. This may
cause the control circuits to malfunction and even damage the AC motor drive. Of course, there are
solutions to increase the noise tolerance of an AC motor drive, but this has its limits. Solving the problem
from the outside as follows is the best.
1. Add a surge suppressor on the relays and contacts to suppress switching surges.
2. Shorten the length of the wiring for the control circuit or serial communication and keep them
separated from the power circuit wiring.
3. Comply with the wiring regulations by using shielded wires and isolation amplifiers for long wire
length.
4. The grounding terminal must comply with the local regulations and be grounded independently; that
is, do not use a common ground with electric welding machines and other power equipment.
5. Connect a noise filter at the mains input terminal of the AC motor drive to filter noise from the power
circuit.
In short, solutions for electromagnetic noise exist of “no product” (disconnect disturbing equipment), “no
spread” (limit emission from disturbing equipment) and “no receive” (enhance immunity).
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