Delta MS300 Series User Manual page 284

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output current and overload time. If overload situation is not frequent and only cares the carrier
frequency operated with the rated current for a long time, and can accept the change of carrier
wave due to short overload, it is recommended to set to 0.
Refer to the following diagram for the level of carrier frequency. Take VFD9A0MS43ANSAA
in normal duty for example: ambient temperature 50 °C, UL open-type, and independent
installation. When the carrier frequency is set to 10 kHz, corresponding to 55 % rated output
current. At the same conditions, ambient temperature 40°C is corresponding to 75 % of rated
output current. When output current is higher than the value, it will auto decrease the carrier
wave according to ambient temperature, output current and overload time. At this time, the
overload capacity of drive is still 150 % of rated current.
 Setting 1:
When the operating point exceeds derating curve 1, carrier frequency is fixed to the set
value. Please select this mode if the change of carrier wave and motor noise caused by ambient
temperature and frequent overload are not accepted. (Please refer to Pr. 00-17)
Refer to the following diagram for the derating level of rated current. Take
VFD9A0MS43ANSAA in normal duty for example, when the carrier frequency is to be
maintained at 10 kHz, the rated current is decreased to 55 %. The OL protection will execute
when the current is 120 % * 55 % = 66 % for a minute. Therefore, it needs to operate by the
curve to keep the carrier frequency.
 Setting 2:
The protection method and action is the same as set to 0, but disables the current limit
when output current is derating Ratio ×120 % (default value) in normal duty and is derating
Ratio ×180 % (default value) in heavy duty.
The advantage is that it can provide higher starting output current when the carrier
frequency setting is higher than the factory setting. The disadvantage is that the carrier wave
derates easily when overload.
Example: when Pr. 06-55 = 0 or 1, over-current stall prevention level = Ratio*Pr. 06-03.
When Pr. 06-55 = 2, over-current stall prevention level = Pr. 06-03.
 It should be used with Pr. 00-16 and Pr.00-17 for setting.
 The derating will also be affected by ambient temperature, please refer to ambient temperature
derating curve.
Example: take VFD9A0MS43ANSAA in normal duty for example: ambient temperature 50
°C, UL open-type, and independent installation. When the carrier frequency is set to 10 kHz,
corresponding to 55 % rated output current. The ambient temperature 60°C is corresponding to
55 % * 75 % of rated output current.
 Derating curve (when Pr. 00-10 = 0 and Pr. 00-11 = 0~3), modulation mode can be adjusted by
Pr. 11-41.
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Chapter 12 Description of Parameter SettingsMS300
12.1-06-19
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Email: info@deltaacdrives.com
Email: info@deltaacdrives.com