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Operation selection function 2 (Pr. 65 to Pr. 79)
3.11.3 PWM carrier frequency selection (Pr. 72, Pr. 240 )
<Setting>
By parameter setting, you can set whether to exercise the Soft-PWM control that changes the motor tone or
select with or without long wiring mode.
• Soft-PWM control is a control method that changes the motor noise from a metallic tone into an unoffending
complex tone.
• Surge voltage is suppressed regardless of wiring length in the long wiring mode. (When operating the 400V
motor with wiring length of 40m or longer, select long wiring mode.)
Parameter Name Factory Setting Setting Range Remarks
72
PWM frequency
selection
1 1 to 6 Simple mode
240 Soft-PWM setting 10 0, 1, 10, 11 Extended mode
Pr. 72
Setting
Description
1 2.25kHz
24.5kHz
3 6.75kHz
49kHz
5 11.25kHz
6 13.5kHz
CAUTION
1. An increased PWM carrier frequency will decrease the motor sound but increase noise and leakage
currents. Therefore, perform the reduction techniques. (Refer to page 12.)
2. Since Pr. 240 is factory-set to "10", PWM carrier frequency is 2.25 kHz constant even if "2" or larger
value is set in Pr. 72. Set "0 or 1" in Pr. 240 to decrease the motor noise.
Pr. 240
Setting
Description
Soft-PWM long wiring mode Remarks
0 Invalid Invalid
———
1
Valid
(when Pr. 72 = "1 or 2")
Invalid
10 Invalid Valid Carrier frequency is 2.25kHz.
(The Pr.72 "PWM frequency selection" setting is
made invalid.)
11 Valid Valid
CAUTION
1. When long wiring mode is made valid, torque reduces about 5% in the constant power range.
2. The output voltage at rated frequency decreases by about 1.5V maximum (200V class)/about 3.0V
maximum (400V class) during V/F control.
3. Use an insulation-enhanced motor for the 400V class. Refer to page 22 for inverter driving of the 400V
class motor.
speed torque position