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Total wiring length
 With induction motor
Connect one or more general-purpose motors within the total wiring length shown in the following table. (The wiring length
should be 100 m or less under vector control.)
Pr.72 setting
(carrier frequency)
2 (2 kHz) or lower
3 (3 kHz) or higher
Total wiring length (FR-A846-00052(1.5K) or higher)
When driving a 400 V class motor by the inverter, surge voltages attributable to the wiring constants may occur at the
motor terminals, deteriorating the insulation of the motor. In this case, take one of the following measures.
• Use a "400 V class inverter-driven insulation-enhanced motor" and set Pr.72 PWM frequency selection according to
the wiring length.
Wiring length 50 m or shorter
15 (14.5 kHz) or lower
• For the FR-A846-01800(55K) or lower, connect a surge voltage suppression filter (FR-ASF-H/FR-BMF-H) at the output
side of the inverter. For the FR-A846-02160(75K) or higher, connect a sine wave filter (MT-BSL/BSC) at the output side
of the inverter.
 With PM motor
The wiring length should be 100 m or shorter when connecting a PM motor.
Use one PM motor for one inverter. Multiple PM motors cannot be connected to an inverter.
When the wiring length exceeds 50 m for a 400 V class motor driven by an inverter under PM sensorless vector control,
set "9" (6 kHz) or less in Pr.72 PWM frequency selection.
• Especially for long-distance wiring or wiring with shielded cables, the inverter may be affected by a charging current caused
by stray capacitances of the wiring, leading to an activation of the overcurrent protection, malfunction of the fast-response
current limit operation, or even to an inverter failure. It may also cause a malfunction or fault of the equipment connected ON
the inverter output side. Stray capacitances of the wiring differ by the installation condition, use the total wiring length in the
table above as reference values. If the fast-response current limit function malfunctions, disable this function. (Refer to Pr.156
Stall prevention operation selection on the FR-A800 Instruction Manual (Detailed).)
• A surge voltage suppression filter (FR-ASF-H/FR-BMF-H) can be used under V/F control and Advanced magnetic flux vector
control. A sine wave filter (MT-BSL/BSC) can be used under V/F control. Do not use the filters under different control
• For the details of Pr.72 PWM frequency selection, refer to the FR-A800 Instruction Manual (Detailed).
• Refer to
page 79
• The carrier frequency is limited during PM sensorless vector control. (Refer to the FR-A800 Instruction Manual (Detailed).)
300 m
200 m
500 m or less
Wiring length 50 m to 100 m
9 (9 kHz) or lower
to drive a 400 V class motor by an inverter.
500 m
300 m
300 m
300 m
300 m+300 m=600 m
Wiring length longer than 100 m
4 (4 kHz) or lower
Main circuit terminals
FR-A846-00052(1.5K) or higher
500 m
500 m


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