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[ 4 ] Output circuit filters (OFLs)
Insert an OFL in the inverter power output circuit to:
- Suppress the voltage fluctuation at the motor power terminals
This protects the motor from insulation damage caused by the application of high voltage surge
currents from the 400 V class of inverters.
- Suppress leakage current (due to higher harmonic components) from the inverter output lines
This reduces the 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).
- Minimize radiation and/or induction noise issued from the inverter output lines
OFLs are effective noise suppression device for long wiring applications such as that used at
plants.
Filter models OFL-***-2 and OFL-***-4 have restrictions on the carrier frequency. For the
use of those filter models, be sure to set the carrier frequency (F26) within the allowable
carrier frequency range given in Table 6.12. (Running the inverter with the carrier frequency
lower than the allowable range overheats the filter.) In addition, to prevent the carrie
frequency from lowering than the allowable range, be sure to disable the automatic lowering
of carrier frequency by setting Bit 0 of function code H98 (Protective/Maintenance
Function) to "0."
A failure could occur.
Figure 6.11 External View of Output Circuit Filter (OFL) and Connection Example
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