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5-39
F26, F27
Motor Sound (Carrier frequency and tone)
Motor sound (Carrier frequency) (F26)
F26 controls the carrier frequency so as to reduce an audible noise generated by the motor or
electromagnetic noise from the inverter itself, and to decrease a leakage current from the
main output (secondary) wirings.
Carrier frequency
0.75 to 16 kHz
Motor sound noise emission
High
↔
Low
Motor temperature (due to harmonics components)
High
↔
Low
Ripples in output current waveform
Large
↔
Small
Leakage current
Low
↔
High
Electromagnetic noise emission
Low
↔
High
Inverter loss
Low
↔
High
Specifying a too low carrier frequency will cause the output current waveform to
have a large amount of ripples. As a result, the motor loss increases, causing the
motor temperature to rise. Furthermore, the large amount of ripples tends to cause
a current limiting alarm. When the carrier frequency is set to 1 kHz or below,
therefore, reduce the load so that the inverter output current comes to be 80% or
less of the rated current.
When a high carrier frequency is specified, the temperature of the inverter may rise
due to an ambient temperature rise or an increase of the load. If it happens, the
inverter automatically decreases the carrier frequency to prevent the inverter
overload alarm
0lu
. With consideration for motor noise, the automatic reduction of
carrier frequency can be disabled. Refer to the description of H98.
Motor sound (Tone) (F27)
F27 changes the motor running sound tone. This setting is effective when the carrier
frequency set to function code F26 is 7 kHz or lower. Changing the tone level may reduce the
high and harsh running noise from the motor.
If the sound level is set too high, the output current may become unstable, or
mechanical vibration and noise may increase. Also, these function codes may not be
very effective for certain types of motor.