(3) Total wiring length (FR-A720/A740)
The overall wiring length for connection of a single motor or multiple motors should be within the value in the table below.
(The wiring length should be 100m (328.08feet) maximum for vector control.)
Pr. 72 PWM frequency selection setting
2 (2kHz) or less
3 to 15 (3kHz to 14.5kHz)
When driving a 400V class motor by the inverter, surge voltages attributable to the wiring constants may occur at the
motor terminals, deteriorating the insulation of the motor.
Take the following measures 1) or 2) in this case.
1) Use a "400V class inverter-driven insulation-enhanced motor" and set frequency in Pr. 72 PWM frequency selection
according to wiring length
2) Connect the surge voltage suppression filter (FR-ASF-H) to the FR-A720-02150 (FR-A740-01100) or less and
the sine wave filter (MT-BSL/BSC) to the FR-A720-02880 (FR-A740-01440) or more on the inverter output side.
· Especially for long-distan ce wiring, the inverter may be affected by a charging current caused by the stray capacitances of the
wiring, leading to a malfunction of the overcurrent protective function or fast response current limit function or a malfunction or
fault of the equipment connected on the inverter output side. If fast response current limit function malfunctions, disable this
function. (For Pr. 156 Stall prevention operation selection, refer to
· For details of Pr. 72 PWM frequency selection , refer to
BSC) for the FR-A720-02880(FR-A740-01440) or more, set "25" (2.5kHz) in Pr. 72.)
For explanation of surge voltage suppression filter (FR-ASF-H) and sine wave filter (MT-BSL/BSC), refer to the manual of each
· Do not perform vector control with a surge voltage suppression filter (FR-ASF-H) or sine wave filer (MT-BSL/BSC) connected.
50m (164.04feet) or
50m (164.04feet) to
14.5kHz or less
9kHz or less
Instruction Manual. (When using an option sine wave filter (MT-BSL/
FR-A720-00080 or more
FR-A740-00040 or more
4kHz or less