ST130 | When should I use an EMI output filter with my frequency inverter?

The frequency inverters have unfiltered outputs. For the majority of applications this provides satisfactory performance, but for a small number of applications output filtering is strongly recommended to increase system functionality, system reliability and system longevity.

These applications include:

• Motors without frequency converter suitable insulation (e.g. older motors)
• Long motor cables, up to 200m
• High capacitive motor cables (e.g. fire protection cables)
• Several motors connected in parallel on one frequency converter

For motors with insulation not suitable for frequency converters:

In any case (ask the motor manufacturer) always check the motor specification to ensure that the motor is designed for use with modern frequency inverters!

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