Chapter 5 Troubleshooting|
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Revision 2016/03, 6ELE, V1.14
5-9
5.13 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 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-EL 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).
5.14 Environmental Condition
Since the AC motor drive is an electronic device, you should comply with the environmental conditions. Here are
some remedial measures if necessary.
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 damage to the AC motor drive.
2. Store the AC motor drive in a clean and dry location, free from corrosive fumes/dust to prevent corrosion
and poor contacts. Poor insulation in a humid location can cause short-circuits. If necessary, install the AC
motor drive in a dust-proof and painted enclosure and in particular situations, use a completely sealed
enclosure.
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.
4. Store within a relative humidity range of 0% to 90% and non-condensing environment. Use an air
conditioner and/or exsiccator.
5.15 Affecting Other Machines
An AC motor drive may affect the operation of other machines due to many reasons. Some solutions are:
High Harmonics at Power Side
High harmonics at power side during running can be improved by:
1. Separate the power system: use a transformer for AC motor drive.
2. Use a reactor at the power input terminal of the AC motor drive.
3. If phase lead capacitors are used (never on the AC motor drive output!!), use serial reactors to prevent
damage to the capacitors damage from high harmonics.
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