Toshiba Tosvert VF-A5 - Manual (Page 72)

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(Special Control Parameters)
C F
PWM carrier frequency
The motor's resonant acoustic noise can be changed by changing the PWM carrier frequency. If resonance
occurs between the motor and the load machine or motor fan cover, change the PWM carrier frequency.
The PWM carrier frequency | CF can be set between 3kHz and 17kHz.
(18.5kW to 75kW units can be adjusted between 3kHz to 15kHz.)
At low-speed and very high-speed operation, the carrier frequency will be automatically adjusted to meet
motor drive requirements.
If the carrier frequency is set higher than the default setting value, the overload trip level will automatically be
reduced, which may result in more frequent overload trips.
15kW and smaller units: if the standard 15kHz setting is changed to 17kHz, the overload trip level will be
reduced 4% for 200V units and
6% for 400V units.
18kW and larger units: if the standard 12kHz setting is changed to 15kHz, the overload trip level will be
reduced 7% for 200V units and 11 % for 400V units.
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