12 Description of Parameter SettingsMS300 (IP66 / NEMA 4X)
12-2
Setting 1:
When the operating point exceeds derating curve 1, the carrier frequeny is fixed to the
set value. Select this mode if the change of carrier wave and motor noise caused by
ambient temperature and frequenct overload are not acceptable. Rever to Pr.00-17.
Refer to the following diagram for the derating level of the rated current. Take
VFD9A0MS43MNSAA in normal duty for example, when the carrier frequency is to be
maintained at 10 kHz, the rated current decreases to 55%. The OL protection executes
when the current is 120 % * 55 % = 66 % for one minute; therefore, it must operate by the
curve to keep the carrier frequency.
Setting 2:
The protection method and action are the same as setting it to 0, but this disables the
current limit when output current is the derating ratio x 120% (default value) in normal duty
and is the derating ratio x 180% (default value) in heavy duty.
The advantage is that this can provide a higher starting output current when the carrier
frequency setting is higher than the defult. The disadvantage is that the carrier wave
derates easily when it overloads.
Example:
When Pr.06-55 = 0 or 1, the over-current stall prevention level = ratio x Pr.06-03. When
Pr.06-55 = 2, the over-current stall prevention level = Pr.06-03.
Use with the settings for Pr.00-16 and Pr.00-17.
The ambient temperature also affects the derating; refer to ambient temperature derating
curve.
Example:
Take VFD9A0MS43MNSAA in normal duty for example: ambient temperature 50°C, UL
open-type, and independent installation. When the carrier frequency is set to 10 kHz, it
corresponds to 55% of the rated output current. The ambient temperature 50°C
corresponds to 55% x 75% of the rated output current.
You can adjust the derating curve modulation mode (when Pr.00-10 = 0 and Pr.00-11 = 0–3)
with Pr.11-41.
In normal duty mode (Pr.00-16 = 0) In heavy duty mdoe (Pr.00-16 = 1)
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