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Chapter 7 Troubleshooting |VFD-S Series
Revision August 2006, SE08, SW V2.61 7-9
7.13 Electromagnetic/Induction Noise
Many sources of noise surround AC motor drives and penetrate it by radiation or conduction. It may
cause malfunctioning of the control circuits 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. Therefore,
solving it from the outside as follows will be the best.
1. Add surge suppressor on the relays and contacts to suppress switching surges.
2. Shorten the wiring length of 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 should comply with the local regulations and be grounded
independently, i.e. not to have 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. VFD-S can have a built-in filter as option.
In short, solutions for electromagnetic noise exist of “no product”(disconnect disturbing equipment),
“no spread”(limit emission for disturbing equipment) and “no receive”(enhance immunity).
7.14 Environmental Condition
Since the AC motor drive is an electronic device, you should comply with the environmental
conditions as stated in the Chapter 2.1. The following step should also be.
1. To prevent vibration, the use of anti-vibration dampers is the last choice. Vibrations must
be within the specification. Vibration causes mechanical stress and it should not occur
frequently, continuously or repeatedly to prevent damaging to the AC motor drive.
2. Store the AC motor drive in a clean and dry location, free from corrosive fumes/dust to
prevent corroded contacts. It also may cause short by low insulation in a humid location.
The solution is to use both paint and dust-proof. For particular occasion, use the
enclosure with whole-seal structure.
3. The ambient temperature should be within the specification. Too high or too low
temperature will affect the lifetime and reliability. For semiconductor components, damage
will occur once any specification is out of range. Therefore, it is necessary to periodically
check air quality and the cooling fan and provide extra cooling of necessary. In addition,
the microcomputer may not work in extremely low temperatures, making cabinet heating
necessary.