58 ACS 300 User’s Manual
Chapter 7 - Drive Parameters
SWITCH f
Motor noise can be minimized by adjusting the switching fre-
quency to a value that does not create resonances in the
motor system. The optimum switching frequency is the low-
est frequency at which the noise is acceptable. This fre-
quency may not be the same for identical motor systems. As
the switching frequency goes up, the inverter efficiency goes
down, so it is best to use a low switching frequency if the
application can tolerate noise.
Note! At output frequencies less than 12 Hz, the switching
frequency may be automatically reduced.
CRIT f1L
(CRIT f1H)
(CRIT f2L)
(CRIT f2H)
In some systems it may be necessary to avoid certain fre-
quencies because of mechanical resonance problems. With
these parameters it is possible to set up two different fre-
quency ranges that the ACS 300 will skip over. It is not nec-
essary that, for example, CRIT f2L be greater than CRIT
f1H, just as long as the LOW parameter in one set is lower
than the HIGH parameter in the same set. Sets may over-
lap, but the skip will be from the lower LOW value to the
higher HIGH value.
Example:
Fan system with bad vibration from 18 Hz to 23
Hz and
from 46 Hz to 52 Hz. Running speed set to 60 Hz
with reference. Set the parameters as follows:
CRIT f1L = 18 Hz and CRIT f1H = 23 Hz
CRIT f2L = 46 Hz and CRIT f2H = 52 Hz
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