Output Circuit Filters (Ofls) - Fuji Electric FRENIC-HVAC User Manual

4.4.1.5

Output circuit filters (OFLs)

Insert an OFL in the inverter power output circuit in order to:
- Suppress the surge voltage at motor terminals
This protects the motor from insulation damage caused by the application of high voltage surge
currents from the 460 V class series of inverters.
- Suppress line leakage current from the inverter output lines (Leakage current to ground cannot be
suppressed.)
This reduces the line leakage current when the motor is connected by long power feed lines. Keep
the length of the power feed line less than 400 m (1300 ft).
Output circuit filters cannot be used with the 575V class series.
Figure 4.7 External View of Output Circuit Filter (OFL) and Connection Example
Inverter
Output circuit filter (OFL)
U
V
W
4-44
U X
Motor
Y
V M
Z
W