8000m Series
- 138 -
There is distributed capacitance between line conductors of VFD output cable. If
the current through the output cable include high order harmonic current, it may
cause syntony which resulting in line-to-line leakage current. In this situation, if a
thermal overload relay is employed, it might be caused malfunction.
To prevent malfunction, lower the carrier frequency or install an output reactor.
When a VFD has been used, it is recommended to use motor overload protection
of VFD instead of employing a thermal overload relay to the motor.
7.3.6 Notice for Installation of EMC Input Filter
1. Usage of an EMC filter must be in strict accordance with its rated specifications.
As a filter belongs to Category I apparatus, its metal ground enclosure must be
contacted to the ground bus of control cabinet as far as possible in surface, and the
continuity of ground conductor must be good, or it will lead to risk of electric
shock and also badly affect the effect of EMC.
2. The ground enclosure of EMC filter must be connected to the same common
ground bus, or it will badly affect the effect of EMC.
3. The filter must be installed as close as possible to the power input terminals of
VFD.
