Output Derating; When Is Derating Necessary - ABB ACS580-04 Hardware Manual

Note:
• To achieve the rated motor power given in the table, the rated current of the drive
must be higher than or equal to the rated motor current. The power ratings apply
to most IEC 34 motors at the nominal voltage of the drive.
• ABB recommends to select the drive, motor and gear combination for the required
motion profile with the DriveSize dimensioning tool available from ABB.

Output derating

When is derating necessary?

￭
The output load capacity ( I
altitude or high temperature environment, and also when the application requires a
high minimum switching frequency. In an environment where more than one type of
derating is necessary (for example, high altitude and high temperature), the effects
of derating are cumulative. If necessary, oversize the drive so that the total derated
output current is sufficient for the motor to reach the full power.
Note:
• The motor can also have a derating on it.
• You can also use the DriveSize tool
(http://new.abb.com/drives/software-tools/drivesize) for derating.
Example 1, IEC: How to calculate the derated current
The IP00 drive type is ACS580-04-725A-4, which has drive output current of 725 A.
Calculate the derated drive output current ( I
altitude and at 50 °C surrounding air temperature as follows:
1. Switching frequency derating (page
The derating factor for 4 kHz switching frequency is 0.78. The derated drive output
current then becomes: I
2. Altitude derating (page
The derating factor for 1500 m is 1 - 1/10 000 m · (1500 - 1000) m = 0.95. The
derated drive output current then becomes: I
3. Surrounding air temperature derating (page
The derating factor for 50 °C ambient temperature is 0.90. The derated drive
output current then becomes: I
Example 2, IEC: How to calculate the required drive
If your application requires continuous 585 A of motor current ( I
frequency, the supply voltage is 400 V and the drive is situated at 1500 m altitude and
at 35 °C surrounding air temperature, calculate the appropriate IP00 drive size
requirement as follows:
1. Switching frequency derating (page
The minimum size required is I
for 4 kHz switching frequency.
2. Altitude derating (page
, I , I ) decreases when the drive is installed into a high
2 Ld Hd
) at 4 kHz switching frequency, at 1500 m
2
181):
= 0.78 · 725 A = 565.5 A
2
181):
= 0.90 · 575.2 A = 483.5 A.
2
181):
= 585 A / 0.78 = 750 A, where 0.78 is the derating
2
181):
= 0.95 · 565.5 A = 537.2 A.
2
180):
) at 4 kHz switching
2
Technical data 179