capacitance can be reduced by effectively shortening the distance between the AC
drive and the motor.
z The higher the carrier frequency is, the larger the leakage current will be. The leakage
current can be reduced by reducing the carrier frequency.
However, reducing the carrier frequency may result in increase of motor noise.
z To install a reactor is also an effective method to remove the leakage current.
z The leakage current may increase following increase of the circuit current. Therefore,
when the motor power is high, the corresponding leakage current is large.
Factors of producing Leakage Current Between Cables and Solutions
There is distributed capacitance between the output cables of the AC drive. If the current
passing the cables contains higher harmonic, it may cause resonance and thus result in
leakage current. If a thermal relay is used in this case, error actions may result.
The solution is to reduce the carrier frequency or install an output reactor. It is
recommended that a thermal relay not be installed before the motor when using the AC
drive, and that electronic over-current protection function of the AC drive be used instead.
7.3.6 Precautions for Installing the EMC Input Filter at Input Side of Power Supply
1. Use the filter with the rated values strictly. The filter belongs to Classification I electric
appliances, and the metal enclosure ground of the filter must be reliably connected to
the metal ground of the installing cabinet and have good conduction continuity.
Otherwise electric shock may result and the EMC effect may be greatly affected.
2. The EMC test shows that the filter and the PE end of the AC drive must be tied to the
same common ground. Otherwise, the EMC effect may be greatly affected.
3. The filter must be installed at a place close to the power input side of the AC drive as
much as possible.
efesotomas
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